The authors would like to acknowledge funding from a National Institutes of Health grant RO1AI049294 (to M. S.).

1. Saflaştırılmış proteinin ATP hidroliz reaksiyonu gerçekleştirme <ol><li> Saf Protein Kuluçka İçin Gerekli Tüm Reaktifler stokları hazırlayın. <ol><li> 100 mM HEPES pH 8.5, 65 mM NaCl ve% 5 gliserol (veya başka bir deney tamponu gibi uygun olduğunda) içeren 5x HEPES / NaCl / gliserol (KŞÇ) tamponu hazırlayın. </li><li> Su (ATPaz metal bağımlı olup olmadığını, ya da başka metal), 100 mM MgCl2 hazırlayın. </li><li> yüksek saflıkta ATP kullanılarak (daha fazla pH ayarı yoktur) 200 mM Tris Base taze 100 mM ATP hazırlayın. Kısım ATP zamanla yıkmak gibi, birkaç hafta daha uzun süre -20 ° C&#39;de ATP stok depolamak ve dondurma ve ATP stok çözdürme kaçınmalı ve. </li><li> 1 at Premix MgCl2 ve ATP: 1 oranında sadece ATP hidroliz reaksiyonu kurmadan önce. </li></ol></li><li> Hazırlayın ve reaksiyonun boyunca düzenli aralıklarla numuneler toplanması için 1.5 ml tüpler etiket. 0 zamanında ve zaman 15, 30 numune toplamak için tüpler hazırlamak,45 ve 60 dakika. Not: Alternatif olarak, sadece 0 ve uç noktada numune toplayın. <ol><li> ATP hidroliz reaksiyonları 01:50 alınan numuneler seyreltmek için her bir tüpe 245 ul 1x KŞÇ tampon ekleyin. </li></ol></li><li> hızlı reaksiyonu durdurmak için numunelerin dondurma için kuru buz etanol banyo hazırlayın. Bir lastik buz kovası veya diğer kasa (plastik olmayan) bir kapta, kuru buz birkaç adet ekleyebilir ve dikkatle kuru buz karşılamak için yeterli% 70-100 etanol dökün. </li><li> Uygun (genellikle 5-10 uM) olarak, 1x KŞÇ tamponunda saflaştırılmış protein sulandırmak ve buz üzerinde tutmak. </li><li> ATP hidroliz reaksiyonları ayarlayın. <ol><li> Her bir örnek için ayrı 0.5 ml tüpler içinde (sırayla) aşağıdaki reaktifler ekleyin: 6 ul 5x hng veya başka bir tampon, 3 ul 100 mM MgCl2 -ATP karışımı (nihai 30 ul hacme kadar), H2O, ve 0.25-5 uM proteini. </li><li> Resim proteini ilave edildiği bir tampon yalnızca negatif kontrol koşulu içerir.</li></ol></li><li> 0 zamanında reaksiyon 5 ul çıkarın 245 ul KŞÇ tampon içeren hazır 1.5 ml tüp içinde 1:50 seyreltilmiş ve hemen kuru buz / etanol banyosu içinde örnek dondurma. </li><li> 37 ° C &#39;de reaksiyonlar ATP hidrolizi, 1 saat boyunca oluşmasına izin vermek için inkübe edin. Her bir aralık (15, 30, 45 ve 60 dakika), tepkime 5 ul alikotları çıkarın ve adım 1.6 olarak KŞÇ tampon içeren etiketli numune tüpleri ekle. </li><li> ATP hidroliz reaksiyonunun sonunda, depolama için bir -80 ° C dondurucu seyreltilmiş numune hareket eder. tüm örnekler tamamen donmuş sağlamak için, devam etmeden önce en az 10 dakika bekleyin. </li></ol> Algılama Reaktif Ücretsiz Pi İçeren 2. inkübe Örnekleri <ol><li> Her bir zaman noktasında ATP hidroliz reaksiyonu kısımlarını ihtiva eden çözülme seyreltilmiş numuneler, oda sıcaklığında (adım 1.6 ve 1.7 de elde edilmiş). </li><li> örnekler ve fosfat standartları ihtiva eden 96 oyuklu bir plaka kurulumu. <ol><li> 0.5 ml tu800 uM standart ul 104.5 ile KŞÇ tampon 5.5 ul ekleyerek 800 uM uM 40 ila (Pi algılama reaktifi ile sağlanır) fosfat standardını sulandırmak olmak. İyice karıştırın ve 96 oyuklu bir plaka de A1, bu 40 uM Pi standart 100 ul ilave edin. </li><li> 1 için kuyuların B1-H1 50 ul KŞÇ tamponu ekleyin: Pi standardının 1 seri dilüsyonları. </li><li> A1 kuyusunda 40 uM Pi 50 ul çıkarın ve iyi B1 50 ul deney tamponu eklemek karıştırın ve iyi B1 50 ul kaldırmak ve iyi G1 ile, iyi C1 devam dilüsyonları ekleyin. Her kuyu aynı hacme sahip olmak için karıştırmadan sonra kuyu G1 50 ul atın. Peki H1 40 0 ​​uM bir Pi standardı oluşturmak için tek tampon içermelidir. Not: bir diğer faktör (örneğin, bir önleyici olarak) numunelere ilave edilmişse, bu koşullar altında fosfat serbest ya absorbans değişiklikleri kontrol etmek için bu faktör içeren bir standart eğri oluşturmak. </li><li> Her samp 50 ul ekleplaka yinelenen le. ve farklı zaman noktalarında yatay sütunlar aynı zaman noktasında dikey (Numune 2 kez 0 = B2, B3 örnek 1 kez 0 = A2, A3) numune ekleyin. Bu kadar 8 örnekleri ve plaka başına 5 kez puan için izin verir. </li></ol></li><li> Numuneler ve standartlar içeren oyuklara (reaktif gerekli (mi) = numune ve standartlar 0,1 x sayısı) her birine, 100 ul kadar malakit yeşili / molibdat Pi tespit reajanı kaldırmak için steril bir pipet kullanın ve kolay pipetleme için bir çanak ekle Çok kanallı bir pipet kullanılarak. Pi kirlenme olasılığı yüksektir olarak, çanak içine doğrudan algılama reaktifi dökmeyin. </li><li> Bir çok kanallı pipet kullanarak, ilk kez noktalarına son kez noktalarından tercihen sırayla, tanıtan kabarcıkları olmadan dikkatlice yukarı pipetleme ve zaman tutarlı bir sayıya indirdi de her Pi algılama reaktif 100 ul ekleyin ve karıştırın. </li><li> Oda sıcaklığında 25 dakika boyunca inkübasyona bırakılır, veya MA görenufacturer en tarifi. </li></ol> Bir Mikroplaka Okuyucusu Kullanma 3. ölçmek Sonuçları <ol><li> absorbans mikro levha okuyucusu kullanarak 650 nm&#39;de numunelerin emme okuyun. </li><li> Bir Pi standart eğri olun. Bir grafik yazılımı kullanılarak, her bir örnek fosfat miktarı için çözmek için kullanılan denklem bulmak için konsantrasyonuna karşı Pi, standart numune için absorbans değerleri grafik. </li><li> fosfat standart kalibrasyon her numune için ATPaz aktivitesinin hesaplanması. Fosfat yayınlandı = (OD 650 - Y kesişimi) / eğim. <ol><li> Her numunenin çiftleri toplam Pi ortalama. Bu numaradan tampon sadece denetimin absorbans okuma çıkartın. seyreltme faktörü ile (bizim örneğimizde 50) bu çarpın. </li><li> ľmol protein başına salınan nmol Pi belirleyin. Kinetik deneyde, her bir zaman noktası için, bu değerleri grafik en az R = 0.99 (şekil 1) doğrusal uyan vermelidir; n iseOT, deney veya daha az protein ya da daha uzun veya daha kısa kuluçka süresi ile ayarlanabilir. </li></ol></li><li> Nmol Pi / umol protein / dak gibi sonuçları istenirse, ya da nmol Pi / mg protein / dak olarak (3 Şekil 2,) temsil eder. </li></ol>

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The authors have nothing to disclose.

Bu biyokimyasal karakterizasyonu için saflaştırılmış proteinlerin in vitro ATPaz aktivitesi ölçüm için genel bir protokoldür. Bu yöntem kolayca optimize edilmiştir; Örneğin protein, tampon ve tuzlu bileşimlerinde, sıcaklık ve deney uzunluğu ve değişken (aralıklarının toplam sayısını da dahil olmak üzere), aralıklarla miktarının ayarlanması aktivitesi kantitatif artırabilir. Ticari olarak temin edilebilen malakit yeşili bazlı reaktifler oldukça duyarlıdır, ve fosfat az miktarda tespit edilebilir (~ 100 ul 50 mmol). Çünkü bu tahlilde hassasiyeti nedeniyle, tek kullanımlık plastik eşya, ultra saf su, tamponlar ve fosfat kirletici yoksun reaktifler kullanmak için çok önemlidir. saflaştırılması proteinlerin sonra boyut dışlama ya da iyon değiştirme kromatografisi proteinin saflığını arttırmak ve kirleri çıkarmak için tavsiye edilir. Nitro ATPaz aktivitesi zayıf gösteren proteinleri için, uyarıcı e arttırmak için reaksiyona ilave edilebilirnzymatic aktivitesi. ATPaz aktivitesi stimüle birçok faktör ile karakterize edilmiştir. Örneğin, kardiyolipin ve diğer membran lipitleri için, örneğin Hsp90 olarak şaperonlar ve özellikle şekillerini veya ortamları destek alan diğer proteinler client proteinlerin içinde ATPazlar 13-15 işlev görmektedir. Laboratuvarımız ilk homolog ATPazların 6 ile karşılaştırıldığında zayıf ATPaz aktivitesi ile monomerlerin arındırarak Epse karakterize edilir. Daha sonra EPSE T2S sisteminde EpsL sitoplazmik alanına, bir transmembran proteini ve EPSE bağlanma ortağı ile copurified zaman, bu reaksiyon karışımına kardiyolipin gibi asidik fosfolipidler eklenmesi önemli ölçüde EPSE 12 ATPaz aktivitesi arttığını keşfettik. Bu büyük olasılıkla taklit oligomerizasyon teşvik edebilir sitoplazmik membran koşullar Epse deneyimleri. Bir çok teknik saflaştırılmış proteinler in vitro ATPase aktivitesini ölçmek için kullanılmıştır. Radyoaktif γ- <sup&gt; 32 P sık sık ve başarılı ATP hidrolizini 14,16 ölçmek için uygulamaya konmuştur Ancak, güvenlik bir endişe ve radyoaktivite laboratuvar kullanımı için onay gerektirir. Çok hassas iken, γ- 32 P kısa yarılanma ömrü, aynı zamanda, bir dezavantajdır. Diğer ticari fosfat saptama yöntemleri, bir flüoresan ürünün oluşumu kullanan olanlar gibi, mevcuttur. Bu yöntemlerin bazıları da çok duyarlıdır, ancak sık sık daha az zaman içinde stabil olan reaktifler ile sonuçlanan reaksiyon diğer enzimlerin ilave edilmesini gerektirir. Buna ek olarak, kitler, stabil bir lüminesans bazlı bir tepkime ATP hidroliz sırasında serbest ADP tespit mevcuttur, ancak bu faaliyet 17 düşük seviyelerde ATPazların için daha az ideal olabilir. Burada tarif edilen deney, tek bir fosfat salma ölçümü adım oluşur çok hassastır ve tipik olarak bir kaç saat içerisinde gerçekleştirilebilir. Bu hazırlık aşamasında da mümkündürBir malakit yeşil içeren substrat yeniden ticari bir satıcıdan 6,9 bir kit satın önlemek için. Bu testte girişmeden önce biri dikkate fosfat algılama reaktifi eklenerek ve absorbans okumaları alarak arasındaki adım nispeten zaman duyarlıdır ve 20-30 dakika arasında olmalıdır olmasıdır. Bu basit protokol (tarif edildiği gibi) ATPaz aktivitesi 15,16,18,19 antagonistleri, alt birimleri, etki ve spesifik artıkları uyarıcı rolünü tespit etmek için kullanılabilir. Bu deney aynı zamanda kataliz sırasında, fosfat fosfataz ya da başka enzimlerin aktivitesini ölçmek için uzatılabilir. Buna ek olarak, bu yöntem, ATPaz inhibitörleri için 20 yüksek verimli tarama uygulanabilir.

ATPases are integral enzymes in many processes across all kingdoms of life. ATPases act as molecular motors that use the energy of ATP hydrolysis to power such diverse reactions as protein trafficking, unfolding, and assembly; replication and transcription; cellular metabolism; muscle movement; cell motility; and ion pumping1-3. Some ATPases are transmembrane proteins involved in transporting solutes across membranes, others are cytoplasmic and may be associated with a biological membrane such as the plasma membrane or those of organelles.
AAA+ ATPases (ATPases associated with various cellular activities) make up a large group of ATPases that share some sequence and structural conservation. These proteins contain conserved nucleotide binding motifs such as Walker-A and -B boxes and form oligomers (generally hexamers) in their active state1. Large conformational changes in these proteins upon nucleotide binding have been characterized among diverse members of the AAA+ family. EpsE is a AAA+ ATPase and member of the bacterial Type II/IV secretion subfamily of NTPases4-6. EpsE powers Type II Secretion (T2S) in Vibrio cholerae, the causative agent of cholera. The T2S system is responsible for the secretion of a wide variety of proteins, such as the virulence factor cholera toxin that causes profuse watery diarrhea when V. cholerae colonizes the human small intestine7. 
Techniques for quantitating in vitro ATPase activity are varied, but commonly measure phosphate release using colorimetric, fluorescent, or radioactive substrates8-11. We describe a basic method for determining in vitro ATPase activity of purified proteins using a colorimetric assay based on a commercially available malachite green-containing substrate that measures liberated inorganic phosphate (Pi). At low pH, malachite green molybdate forms a complex with Pi and the level of complex formation can be measured at 650 nm. This simple and sensitive assay may be used to functionally characterize new ATPases and to evaluate the roles of potential activators or inhibitors, to determine the importance of domains and/or specific residues, or to assess the effect of particular treatments on enzymatic activity.

<table border="0" cellpadding="0" cellspacing="0" width="654">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:221px;">HEPES buffer</td>
			<td style="width:128px;">Fisher</td>
			<td style="width:108px;">BP310-500</td>
			<td style="width:197px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sodium chloride</td>
			<td>Fisher</td>
			<td>BP358-212</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;">Magnesium chloride</td>
			<td>Fisher</td>
			<td>BP214-500</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Adenosine triphosphate (ATP)</td>
			<td>Fisher</td>
			<td>BP41325</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">96-well plates (clear, flat-bottom)</td>
			<td>VWR</td>
			<td>82050-760</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">BIOMOL Green</td>
			<td>Enzo Life Sciences</td>
			<td>BML-AK111</td>
			<td>Preferred phosphate detection reagent. Caution: irritant.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Microplate reader</td>
			<td></td>
			<td></td>
			<td>BioTek Synergy or comparable</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Prism 5</td>
			<td colspan="2">GraphPad Software</td>
			<td></td>
		</tr>
	</tbody>
</table>

measuring in vitro atpase activity for enzymatic characterization

ATP-hidrolize edici enzimler ya da ATPaz, hücresel fonksiyonların çeşitli bir dizi çok önemli bir rol oynar. Bu dinamik proteinler, protein kaçakçılığı ve yıkımı, madde geçişinde ve hücresel hareketler gibi mekanik çalışmaları için enerji üretebilir. Burada açıklanan protokol fonksiyonel karakterizasyon için saflaştınldı ATPazların in vitro aktivitesini ölçmek için basit bir testtir. Proteinler, inorganik fosfat serbest sonuçlanan bir reaksiyon ATP hidroliz ve serbest fosfat miktarının bir kolorimetrik tahlil kullanılarak hesaplanır. Bu son derece uyumlu bir protokol kinetik ve bitiş noktası deneylerinde ATPaz aktivitesini ölçmek için ayarlanabilir. Temsili bir protokol aktivitesi ve Epse gereklerine göre burada sağlanan, AAA + ATPaz bakterisinin Vibrio cholerae Tip II salgılanması yer. aktivitesini ölçmek için ihtiyaç duyulan pürifiye protein miktarı, tayinin uzunluğu ve SA zamanlaması ve sayısımpling aralıkları, tampon ve tuzlu bileşim olup, sıcaklık, ko-faktörler, uyarıcı (eğer varsa) gibi burada açıklanan farklı olabilir, ve bu nedenle bazı optimizasyon gerekli olabilir. Bu protokol karakterize ATPaz&#39;ları için temel bir çerçeve sağlar ve hızlı bir şekilde gerçekleştirilir ve kolay gerektiğinde ayarlanabilir.

T2S ATPaz EPSE in vitro aktivitesi sitoplazmik EpsL (EPSE-cytoEpsL) alanında ve asidik fosfolipid kardiyolipin 12 ilavesi ile EPSE bölgesinin copurification ile stimüle edilebilir. Deney kullanılarak protein varyant formlarının vahşi tip (WT) etkinliğinin kıyaslanmasıyla ATP hidroliz özellikle EPSE kalıntılarının rolü belirlemek için de mümkündür. Burada, EPSE, çinko bağlayıcı alan olarak iki lisin artığına ikame etkisi EPSE K417AK419A-cytoEpsL varyantına saflaştırılarak WT EPSE-cytoEpsL ATPaz aktivitesi karşılaştırarak ölçülmüştür. Şekil 1 &#39;de, fosfat salma 1 saat kinetik deneyde, kinetik ATPaz aktivitesinin tayini için daha kesin bir gereklilik boyunca doğrusal olarak ilerler. Iki kez, üç kez tahlil edilir ve nicelleştirilmiştir şekil 1 ile aynı saflaştırılmış protein örneklerinden Şekil 2 veriler, Şekil açısındanfosfat salınımı ortalama oran. Bu veriler, K417 ve K419 EPSE ATPaz aktivitesi için önemli gibi görünmektedir göstermektedir. Bununla birlikte, uyarılmamış (Resim kardiyolipin) ATPaz aktivitesi oranlarının karşılaştırılması (Şekil 3) K417 ve K419 EPSE bazal aktivite değil, kardiyolipin tarafından uyarılabilir proteinin yeteneğine katkıda bulunmadığını göstermektedir. EPSE çinko bağlayıcı alan pozitif yüklü lizinlerinin doğrudan ve böylece EPSE ATPaz aktivitesi fosfolipid aracılı uyarılmasına katkıda negatif yüklü fosfolipidler ile etkileşime girebilir. <img alt="Şekil 1" src="/files/ftp_upload/54305/54305fig1.jpg" /> Şekil 1:. Fosfat bir saat kinetik kardiyolipin uyarılmış sığır serum albümini ile EPSE K417AK419A-cytoEpsL 0.5 uM WT EPSE-cytoEpsL fosfat serbest karşılaştırırken ATPase Deneyi (BSA), bir kinetik ATPase Deneyi lineer Çıkış şekilde deneye tabi tutulurBir negatif kontrol. Veriler [zamana karşı serbest fosfat (y-ekseni) (x-ekseni) miktarı] çizilmiştir ve doğrusal regresyon analizine tabi tutulmuştur. eğimi ATP hidroliz hızını temsil eder. Üç proteinlerin doğrusal regresyon denklemleri ile temsil grafiği gösterilmektedir. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54305/54305fig1large.jpg" target="_blank">Bu rakamın büyük halini görmek için lütfen buraya tıklayınız.</a> <img alt="şekil 2" src="/files/ftp_upload/54305/54305fig2.jpg" /> Şekil 2.:., Çift lisinin Mutasyonlar EPSE Alan Uyarılmış ATPaz aktivitesini azaltmak Çinko bağlayıcı Şekil 1 &#39;deki ile aynı protein ve koşullara 1 saat kinetik kardiyolipin uyarılmış ATPase deneyinde sonuçları Tahliller, teknik yinelenen ve üç ayrı kez yapıldı ATP hidroliz hızı iM pr başına dakikada üretilen nmol fosfat olarak hesaplanmıştır<html> lineer regresyon denklemleri kullanılarak otein. Standart hata ile ortalama sonuçları görüntülenir. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54305/54305fig2large.jpg" target="_blank">Bu rakamın büyük halini görmek için lütfen buraya tıklayınız.</a> <img alt="Şekil 3," src="/files/ftp_upload/54305/54305fig3.jpg" /> Şekil 3: çift lizin Mutasyonlar EPSE çinko bağlayıcı alan olarak Stimüle edilmemiş ATPaz aktivitesine müdahale Not gece boyunca (16 saat) uyarılmamış uç BSA ile EPSE K417AK419A-cytoEpsL 5 uM WT EPSE-cytoEpsL etkinliği ile karşılaştırılması (Resim kardiyolipin) ATPaz testi. bir negatif kontrol olarak. Tahliller teknik nüsha halinde üç ayrı kez yapıldı ve standart hata ile ortalama sonuçlar gösterilmektedir. 16 saatlik bir süre içinde analiz edildi uyarılmamış EPSE ATPaz faaliyetinin bazal seviyesi ~ daha düşük 1 saat kinetik kardiyolipin uyarılmış aktivitesi 1000 kat.e.com/files/ftp_upload/54305/54305fig2large.jpg &quot;target =&quot; _ blank &quot;&gt; bu rakamın daha büyük bir versiyonunu görmek için lütfen buraya tıklayınız.

Watch this Scientific Journal Video about Measuring In Vitro ATPase Activity for Enzymatic Characterization at JoVE.com

Measuring In Vitro ATPase Activity for Enzymatic Characterization

We describe a basic protocol for quantitating in vitro ATPase activity. This protocol can be optimized based on the level of activity and requirements for a given purified ATPase.

ölçme<em&gt; İn Vitro</emEnzimatik Karakterizasyonu için&gt; ATPaz Aktivitesi

Adenosine triphosphate-hydrolyzing enzymes, or ATPases, play a critical role in a diverse array of cellular functions. These dynamic proteins can generate ...

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Nanyang Technological University

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Biology

Measuring In Vitro ATPase Activity for Enzymatic Characterization

17.9K Görüntüleme.  University of Michigan. We describe a basic protocol for quantitating in vitro ATPase activity. This protocol can be optimized based on the level of activity and requirements for a given purified ATPase.

Video: Measuring In Vitro ATPase Activity for Enzymatic Characterization

An Assay for Measuring the Activity of Escherichia coli Inducible Lysine Decarboxyase

Escherichia coli is an enteric bacterium that is capable of growing over a wide range of pH values (pH 5 - 9)1 and, incredibly, is able to survive extreme acid stresses including passage through the mammalian stomach where the pH can fall to as low as pH 1 - 22. To enable such a broad range of acidic pH survival, E. coli possesses four different inducible amino acid decarboxylases that decarboxylate their substrate amino acids in a proton-dependent manner thus raising the internal pH. The decarboxylases include the glutamic acid decarboxylases GadA and GadB3, the arginine decarboxylase AdiA4, the lysine decarboxylase LdcI5, 6 and the ornithine decarboxylase SpeF7. All of these enzymes utilize pyridoxal-5'-phospate as a co-factor8 and function together with inner-membrane substrate-product antiporters that remove decarboxylation products to the external medium in exchange for fresh substrate2. In the case of LdcI, the lysine-cadaverine antiporter is called CadB. Recently, we determined the X-ray crystal structure of LdcI to 2.0 &#197;, and we discovered a novel small-molecule bound to LdcI the stringent response regulator guanosine 5'-diphosphate,3'-diphosphate (ppGpp) 14. The stringent response occurs when exponentially growing cells experience nutrient deprivation or one of a number of other stresses9. As a result, cells produce ppGpp which leads to a signaling cascade culminating in the shift from exponential growth to stationary phase growth10. We have demonstrated that ppGpp is a specific inhibitor of LdcI 14. Here we describe the lysine decarboxylase assay, modified from the assay developed by Phan et al.11, that we have used to determine the activity of LdcI and the effect of pppGpp/ppGpp on that activity. The LdcI decarboxylation reaction removes the &alpha;-carboxy group of L-lysine and produces carbon dioxide and the polyamine cadaverine (1,5-diaminopentane)5. L-lysine and cadaverine can be reacted with 2,4,6-trinitrobenzensulfonic acid (TNBS) at high pH to generate N,N'-bistrinitrophenylcadaverine (TNP-cadaverine) and N,N&#8242;-bistrinitrophenyllysine (TNP-lysine), respectively11. The TNP-cadaverine can be separated from the TNP-lysine as the former is soluble in organic solvents such as toluene while the latter is not (See Figure 1). The linear range of the assay was determined empirically using purified cadaverine.

An Assay for Measuring the Activity of Escherichia coli Inducible Lysine Decarboxyase

The activity of the inducible lysine decarboxylase is monitored by reacting the substrate L-lysine and the product cadaverine with 2,4,6-trinitrobenzensulfonic acid to form adducts that have differential solubility in toluene.

Etkinlik Ölçüm Bir Testi Escherichia coli Lizin Decarboxyase Đndüklenebilir

Escherichia coli is an enteric bacterium that is capable of growing over a wide range of pH values (pH 5 - 9)1 and, incredibly, is able to survive extreme ...

Biyoloji

Assaying the Kinase Activity of LRRK2 in vitro

Leucine Rich Repeat Kinase 2 (LRRK2) is a 2527 amino acid member of the ROCO family of proteins, possessing a complex, multidomain structure including a GTPase domain (termed ROC, for Ras of Complex proteins) and a kinase domain1. The discovery in 2004 of mutations in LRRK2 that cause Parkinson's disease (PD) resulted in LRRK2 being the focus of a huge volume of research into its normal function and how the protein goes awry in the disease state2,3. Initial investigations into the function of LRRK2 focused on its enzymatic activities4-6. Although a clear picture has yet to emerge of a consistent alteration in these due to mutations, data from a number of groups has highlighted the importance of the kinase activity of LRRK2 in cell death linked to mutations7,8. Recent publications have reported inhibitors targeting the kinase activity of LRRK2, providing a key experimental tool9-11. In light of these data, it is likely that the enzymatic properties of LRRK2 afford us an important window into the biology of this protein, although whether they are potential drug targets for Parkinson's is open to debate.
A number of different approaches have been used to assay the kinase activity of LRRK2. Initially, assays were carried out using epitope tagged protein overexpressed in mammalian cell lines and immunoprecipitated, with the assays carried out using this protein immobilised on agarose beads4,5,7. Subsequently, purified recombinant fragments of LRRK2 in solution have also been used, for example a GST tagged fragment purified from insect cells containing residues 970 to 2527 of LRRK212. Recently, Dani&euml;ls et al. reported the isolation of full length LRRK2 in solution from human embryonic kidney cells, however this protein is not widely available13. In contrast, the GST fusion truncated form of LRRK2 is commercially available (from Invitrogen, see table 1 for details), and provides a convenient tool for demonstrating an assay for LRRK2 kinase activity. Several different outputs for LRRK2 kinase activity have been reported. Autophosphorylation of LRRK2 itself, phosphorylation of Myelin Basic Protein (MBP) as a generic kinase substrate and phosphorylation of an artificial substrate - dubbed LRRKtide, based upon phosphorylation of threonine 558 in Moesin - have all been used, as have a series of putative physiological substrates including &alpha;-synuclein, Moesin and 4-EBP14-17. The status of these proteins as substrates for LRRK2 remains unclear, and as such the protocol described below will focus on using MBP as a generic substrate, noting the utility of this system to assay LRRK2 kinase activity directed against a range of potential substrates.

Assaying the Kinase Activity of LRRK2 in vitro

Leucine Rich Repeat Kinase 2 is a large multidomain kinase, mutations in which are the most common genetic cause of Parkinson's disease. Analysis of the kinase activity of this protein has proven to be a crucial tool in understanding the biology and dysfunction of this protein. In this paper, in vitro assaying of the kinase activity of LRRK2 and a selection of its mutants is described, providing an experimental system to examine phosphorylation of putative substrates and potential dysfunction of LRRK2 in disease.

LRRK2 Kinaz Aktivitesi Assaying In vitro</em

Leucine Rich Repeat Kinase 2 (LRRK2) is a 2527 amino acid member of the ROCO family of proteins, possessing a complex, multidomain structure including a ...

Isolation of Ribosome Bound Nascent Polypeptides in vitro to Identify Translational Pause Sites Along mRNA

The rate of translational elongation is non-uniform. mRNA secondary structure, codon usage and mRNA associated proteins may alter ribosome movement on the messagefor review see 1. However, it's now widely accepted that synonymous codon usage is the primary cause of non-uniform translational elongation rates1. Synonymous codons are not used with identical frequency. A bias exists in the use of synonymous codons with some codons used more frequently than others2. Codon bias is organism as well as tissue specific2,3. Moreover, frequency of codon usage is directly proportional to the concentrations of cognate tRNAs4. Thus, a frequently used codon will have higher multitude of corresponding tRNAs, which further implies that a frequent codon will be translated faster than an infrequent one. Thus, regions on mRNA enriched in rare codons (potential pause sites) will as a rule slow down ribosome movement on the message and cause accumulation of nascent peptides of the respective sizes5-8. These pause sites can have functional impact on the protein expression, mRNA stability and protein foldingfor review see 9. Indeed, it was shown that alleviation of such pause sites can alter ribosome movement on mRNA and subsequently may affect the efficiency of co-translational (in vivo) protein folding1,7,10,11. To understand the process of protein folding in vivo, in the cell, that is ultimately coupled to the process of protein synthesis it is essential to gain comprehensive insights into the impact of codon usage/tRNA content on the movement of ribosomes along mRNA during translational elongation.
Here we describe a simple technique that can be used to locate major translation pause sites for a given mRNA translated in various cell-free systems6-8. This procedure is based on isolation of nascent polypeptides accumulating on ribosomes during in vitro translation of a target mRNA. The rationale is that at low-frequency codons, the increase in the residence time of the ribosomes results in increased amounts of nascent peptides of the corresponding sizes. In vitro transcribed mRNA is used for in vitro translational reactions in the presence of radioactively labeled amino acids to allow the detection of the nascent chains. In order to isolate ribosome bound nascent polypeptide complexes the translation reaction is layered on top of 30% glycerol solution followed by centrifugation. Nascent polypeptides in polysomal pellet are further treated with ribonuclease A and resolved by SDS PAGE. This technique can be potentially used for any protein and allows analysis of ribosome movement along mRNA and the detection of the major pause sites. Additionally, this protocol can be adapted to study factors and conditions that can alter ribosome movement and thus potentially can also alter the function/conformation of the protein.

Isolation of Ribosome Bound Nascent Polypeptides in vitro to Identify Translational Pause Sites Along mRNA

A technique to identify translational pause sites on mRNA is described. This procedure is based on isolation of nascent polypeptides accumulating on ribosomes during in vitro translation of a target mRNA, followed by the size analysis of the nascent chains using a denaturing gel electrophoresis.

Ribozom Bağlı Doğan Polipeptitler İzolasyonu<em&gt; In vitro</em&gt; MRNA boyunca Translasyonel Duraklat Siteleri Belirleme

The rate of translational elongation is non-uniform. mRNA secondary structure, codon usage and mRNA associated proteins may alter ribosome movement on the ...

Measuring Cation Transport by Na,K- and H,K-ATPase in Xenopus Oocytes by Atomic Absorption Spectrophotometry: An Alternative to Radioisotope Assays

Whereas cation transport by the electrogenic membrane transporter Na+,K+-ATPase can be measured by electrophysiology, the electroneutrally operating gastric H+,K+-ATPase is more difficult to investigate. Many transport assays utilize radioisotopes to achieve a sufficient signal-to-noise ratio, however, the necessary security measures impose severe restrictions regarding human exposure or assay design. Furthermore, ion transport across cell membranes is critically influenced by the membrane potential, which is not straightforwardly controlled in cell culture or in proteoliposome preparations. Here, we make use of the outstanding sensitivity of atomic absorption spectrophotometry (AAS) towards trace amounts of chemical elements to measure Rb+ or Li+ transport by Na+,K+- or gastric H+,K+-ATPase in single cells. Using Xenopus oocytes as expression system, we determine the amount of Rb+ (Li+) transported into the cells by measuring samples of single-oocyte homogenates in an AAS device equipped with a transversely heated graphite atomizer (THGA) furnace, which is loaded from an autosampler. Since the background of unspecific Rb+ uptake into control oocytes or during application of ATPase-specific inhibitors is very small, it is possible to implement complex kinetic assay schemes involving a large number of experimental conditions simultaneously, or to compare the transport capacity and kinetics of site-specifically mutated transporters with high precision. Furthermore, since cation uptake is determined on single cells, the flux experiments can be carried out in combination with two-electrode voltage-clamping (TEVC) to achieve accurate control of the membrane potential and current. This allowed e.g. to quantitatively determine the 3Na+/2K+ transport stoichiometry of the Na+,K+-ATPase and enabled for the first time to investigate the voltage dependence of cation transport by the electroneutrally operating gastric H+,K+-ATPase. In principle, the assay is not limited to K+-transporting membrane proteins, but it may work equally well to address the activity of heavy or transition metal transporters, or uptake of chemical elements by endocytotic processes.

Measuring Cation Transport by Na,K- and H,K-ATPase in Xenopus Oocytes by Atomic Absorption Spectrophotometry: An Alternative to Radioisotope Assays

We describe a method to quantify the activity of K+-countertransporting P-type ATPases by heterologous expression of the enzymes in Xenopus oocytes and measuring Rb+ or Li+ uptake into individual cells by atomic absorption spectrophotometry. The method is a sensitive and safe alternative to radioisotope flux experiments facilitating complex kinetic studies.

Na, K ve H, K-ATPaz bölgesindeki tarafından Katyon Taşıma Ölçüm<em&gt; Xenopus</emAtomik Absorpsiyon Spektrofotometresi ile&gt; Oosit: Radyoizotop Tahliller Alternatif Bir

Whereas cation transport by the electrogenic membrane transporter Na+,K+-ATPase can be measured by electrophysiology, the electroneutrally operating ...

Measuring Glutathione-induced Feeding Response in Hydra

Hydra is among the most primitive organisms possessing a nervous system and chemosensation for detecting reduced glutathione (GSH) for capturing the prey. The movement of prey organisms causes mechanosensory discharge of the stinging cells called nematocysts from hydra, which are inserted into the prey. The feeding response in hydra, which includes curling of the tentacles to bring the prey towards the mouth, opening of the mouth and consequent engulfing of the prey, is triggered by GSH present in the fluid released from the injured prey. To be able to identify the molecular mechanism of the feeding response in hydra which is unknown to date, it is necessary to establish an assay to measure the feeding response. Here, we describe a simple method for the quantitation of the feeding response in which the distance between the apical end of the tentacle and mouth of hydra is measured and the ratio of such distance before and after the addition of GSH is determined. The ratio, called the relative tentacle spread, was found to give a measure of the feeding response. This assay was validated using a starvation model in which starved hydra show an enhanced feeding response in comparison with daily fed hydra.

Here we describe a simple assay for the quantification of the feeding response in hydra induced by the reduced form of glutathione. This assay relies on measuring the distance between the apical end of the tentacle and mouth of hydra.

Hydra Glutatyon kaynaklı Besleme Tepki Ölçüm

Hydra is among the most primitive organisms possessing a nervous system and chemosensation for detecting reduced glutathione (GSH) for capturing the prey. ...

Functional Reconstitution and Channel Activity Measurements of Purified Wildtype and Mutant CFTR Protein

The Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) is a unique channel-forming member of the ATP Binding Cassette (ABC) superfamily of transporters. The phosphorylation and nucleotide dependent chloride channel activity of CFTR has been frequently studied in whole cell systems and as single channels in excised membrane patches. Many Cystic Fibrosis-causing mutations have been shown to alter this activity. While a small number of purification protocols have been published, a fast reconstitution method that retains channel activity and a suitable method for studying population channel activity in a purified system have been lacking. Here rapid methods are described for purification and functional reconstitution of the full-length CFTR protein into proteoliposomes of defined lipid composition that retains activity as a regulated halide channel. This reconstitution method together with a novel flux-based assay of channel activity is a suitable system for studying the population channel properties of wild type CFTR and the disease-causing mutants F508del- and G551D-CFTR. Specifically, the method has utility in studying the direct effects of phosphorylation, nucleotides and small molecules such as potentiators and inhibitors on CFTR channel activity. The methods are also amenable to the study of other membrane channels/transporters for anionic substrates.

Described here is a rapid and effective procedure for functional reconstitution of purified wild-type and mutant CFTR protein that preserves activity for this chloride channel, which is defective in Cystic Fibrosis. Iodide efflux from reconstituted proteoliposomes mediated by CFTR allows studies of channel activity and the effects of small molecules.

Saf Yabanitip ve Mutant CFTR Protein Fonksiyonel Sulandırma ve Kanal Aktivite Ölçümleri

The Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) is a unique channel-forming member of the ATP Binding Cassette (ABC) superfamily of ...

Method for Measuring the Activity of Deubiquitinating Enzymes in Cell Lines and Tissue Samples

The ubiquitin-proteasome system has recently been implicated in various pathologies including neurodegenerative diseases and cancer. In light of this, techniques for studying the regulatory mechanism of this system are essential to elucidating the cellular and molecular processes of the aforementioned diseases. The use of hemagglutinin derived ubiquitin probes outlined in this paper serves as a valuable tool for the study of this system. This paper details a method that enables the user to perform assays that give a direct visualization of deubiquitinating enzyme activity. Deubiquitinating enzymes control proteasomal degradation and share functional homology at their active sites, which allows the user to investigate the activity of multiple enzymes in one assay. Lysates are obtained through gentle mechanical cell disruption and incubated with active site directed probes. Functional enzymes are tagged with the probes while inactive enzymes remain unbound. By running this assay, the user obtains information on both the activity and potential expression of multiple deubiquitinating enzymes in a fast and easy manner. The current method is significantly more efficient than using individual antibodies for the predicted one hundred deubiquitinating enzymes in the human cell.

The current protocol details a method for measuring the activity of functionally homologous deubiquitinating enzymes. Specialized probes covalently modify the enzyme and allow for detection. This method holds the potential to identify new therapeutic targets.

Hücre Kuşakları ve Doku Örneklerinde Deubiquitinating Enzim aktivitesinin ölçülmesi için bir yöntem

The ubiquitin-proteasome system has recently been implicated in various pathologies including neurodegenerative diseases and cancer. In light of this, ...

In Vitro Assay to Measure Phosphatidylethanolamine Methyltransferase Activity

Phosphatidylethanolamine methyltransferases are biosynthetic enzymes that catalyze the transfer of one or more methyl group(s) from S-adenosyl-L-methionine onto phosphatidylethanolamine, monomethyl-phosphatidylethanolamine, or dimethyl-phosphatidylethanolamine to give either monomethyl-phosphatidylethanolamine, dimethyl-phosphatidylethanolamine or phosphatidylcholine. These enzymes are ubiquitous in animal cells, fungi, and are also found in approximately 10% of bacteria. They fulfill various important functions in cell physiology beyond their direct role in lipid metabolism such as in insulin resistance, diabetes, atherosclerosis, cell growth, or virulence. The present manuscript reports on a simple cell-free enzymatic assay that measures the transfer of tritiated methyl group(s) from S-[Methyl-3H]adenosyl-L-methionine onto phosphatidylethanolamine using whole cell extracts as an enzyme source. The resulting methylated forms of phosphatidylethanolamine are hydrophobic and thus, can be separated from water soluble S-[Methyl-3H]adenosyl-L-methionine by organic extraction. This assay can potentially be applied to any other cell types and used to test inhibitors/drugs specific to a phosphatidylethanolamine methyltransferase of interest without the need to purify the enzyme.

In Vitro Assay to Measure Phosphatidylethanolamine Methyltransferase Activity

The present report describes an in vitro enzymatic assay to measure phosphatidylethanolamine methyltransferase activity using Leishmania cell extracts. This assay is based on the transfer of a radioactive methyl group from S-[Methyl-3H]adenosyl-L-methionine onto endogenous phosphatidylethanolamine.

Vitro Tahlil Fosfatidiletanolamin Metiltransferaz Aktivite Tedbir

Phosphatidylethanolamine methyltransferases are biosynthetic enzymes that catalyze the transfer of one or more methyl group(s) from ...

Measuring Lactase Enzymatic Activity in the Teaching Lab

Understanding how enzymes work, and relating this to real life examples, is critical to a wide range of undergraduate degrees in the biological and biomedical sciences. This easy to follow protocol was developed for first year undergraduate pharmacy students and provides an entry-level introduction to enzyme reactions and analytical procedures for enzyme analysis. The enzyme of choice is lactase, as this represents an example of a commercially available enzyme relevant to human disease/pharmaceutical practice. Lactase is extracted from dietary supplement tablets, and assessed using a colorimetric assay based upon hydrolysis of an artificial substrate for lactase (ortho-nitrophenol-beta-D-galactopyranoside, ONPG). Release of ortho-nitrophenol following the hydrolytic cleavage of ONPG by lactase is measured by a change in absorbance at 420 nm, and the effect of the temperature on the enzymatic reaction is evaluated by carrying out the reaction on ice, at room temperature and at 37 &#176;C. More advanced analysis can be implemented using this protocol by assessing the enzyme activity under different conditions and using different reagents.

The enzymatic activity of lactase is essential for the catabolic processing of the disaccharide lactose. Here, the activity of lactase found in dietary supplements is assayed using a colorimetric assay. This provides students with an experimental platform for understanding the activity of lactase and enzyme kinetics.

Laktaz enzim etkinliğin ölçülmesi öğretim laboratuarında

Understanding how enzymes work, and relating this to real life examples, is critical to a wide range of undergraduate degrees in the biological and ...

In Vitro SUMOylation Assay to Study SUMO E3 Ligase Activity

Small ubiquitin-like modifier (SUMO) modification is an important post-translational modification (PTM) that mediates signal transduction primarily through modulating protein-protein interactions. Similar to ubiquitin modification, SUMOylation is directed by a sequential enzyme cascade including E1-activating enzyme (SAE1/SAE2), E2-conjugation enzyme (Ubc9), and E3-ligase (i.e., PIAS family, RanBP2, and Pc2). However, different from ubiquitination, an E3 ligase is non-essential for the reaction but does provide precision and efficacy for SUMO conjugation. Proteins modified by SUMOylation can be identified by in vivo assay via immunoprecipitation with substrate-specific antibodies and immunoblotting with SUMO-specific antibodies. However, the demonstration of protein SUMO E3 ligase activity requires in vitro reconstitution of SUMOylation assays using purified enzymes, substrate, and SUMO proteins. Since in the in vitro reactions, usually SAE1/SAE2 and Ubc9, alone are sufficient for SUMO conjugation, enhancement of SUMOylation by a putative E3 ligase is not always easy to detect. Here, we describe a modified in vitro SUMOylation protocol that consistently identifies SUMO modification using an in vitro reconstituted system. A step-by-step protocol to purify catalytically active K-bZIP, a viral SUMO-2/3 E3 ligase, is also presented. The SUMOylation activities of the purified K-bZIP are shown on p53, a well-known target of SUMO. This protocol can not only be employed for elucidating novel SUMO E3 ligases, but also for revealing their SUMO paralog specificity.

In Vitro SUMOylation Assay to Study SUMO E3 Ligase Activity

Unlike ubiquitin ligases, few E3 SUMO ligases have been identified. This modified in vitro SUMOylation protocol is able to identify novel SUMO E3 ligases by an in vitro reconstitution assay.

Vitro SUMOylation SUMO E3 ligaz etkinlik eğitim için tahlil

Small ubiquitin-like modifier (SUMO) modification is an important post-translational modification (PTM) that mediates signal transduction primarily ...