우리는 중국 국립 자연 과학 재단 (No 21205078)과 중국 고등 교육 박사 과정 프로그램 (No.20123120110002)의 지원에 감사드립니다. 이 연구는 중국의 국가 핵심 연구 및 개발 프로그램 (2016YFB1102303), 중국의 국가 기본 연구 프로그램 (973 프로그램 2015CB352001) 및 중국 자연 과학 재단 (61378060)에 의해 부분적으로 지원되었습니다.

1. SGE 칩의 기본 설계 <ol><li> 폴리 메틸 메타 크릴 레이트 (PMMA) 또는 폴리 카보네이트와 같은 투명 플라스틱을 사용하십시오. 참고 : SGE 칩은 그림 1B 에 나와 있습니다. SGE 칩은 TBE 버퍼 용 원통형 구멍, DNA 분리 용 채널 및 전극 용 구멍을 따라 삽입 된 2 개의 차선으로 구성됩니다. </li><li> 레이저 조각기를 사용하여 PMMA 블록에서 SGE 채널 어레이를 제작하십시오. 참고 : 칩의 기하학적 매개 변수는 분리 할 DNA의 크기에 따라 다릅니다. 예를 들어, DNA 조각이 1,000bp보다 작 으면 SGE 칩의 최적 채널 매개 변수는 2.5mm x 4.0mm x 90mm (폭 x 깊이 x 길이)입니다. </li><li> SGE 디자인을 기반으로 DNA 샘플을로드하기 위해 칩에 우물을 만들기 위해 빗을 제작하십시오. </li></ol> 2. 아가로 오스 겔의 제조 <ol><li> 10 × TBE (1 × TBE =89 mM 트리스, 89 mM 붕산 및 2 mM EDTA; pH 8.4) 및 증류수를 1:19 비율로 혼합 하였다. </li><li> 100-bp DNA 사다리를 분리하기위한 1.0 % 아가 로즈 겔을 준비한다. 참고 : 0.5x TBE 버퍼에서 아가로 오스의 농도는 분리 할 DNA 단편의 크기에 따라 다릅니다. </li><li> 플라스크에 0.1 g의 아가로 오스를 넣고 0.5 x TBE 완충액 10 mL를 넣는다. 참고 : 준비된 용액의 부피는 플라스크 용량의 1/3보다 적어야합니다. </li><li> 플라스크를 방부제 필름으로 밀봉 한 다음 전자 레인지 (중간, 1.0 분)에서 아가로 오스 / 버퍼 혼합물을 가열하십시오. 플라스크를 전자 렌지에 넣기 전에 방폭이 될 경우 방수 필름에 구멍을 뚫습니다. </li><li> SGE 칩의 4 채널에 녹인 아가로 오스 솔루션 2.7 ML을 부어. 우물을 만들기 위해 빗을 아가로 오스 용액에 넣으십시오. 참고 : 녹은 아가로 오스 솔루션은 실온에서 3 분 후 겔 상태로 냉각됩니다. </li><li> g에서 빗을 꺼냅니다.겔을 덮고 0.5x TBE 완충액 0.9 mL를 넣어 젤을 덮는다. </li></ol> 3. SGE 칩에서 전기 영동 실행하기 <ol><li> LED 광원을 켜고 광원 위에 425 ~ 505 nm 밴드 패스 필터를 놓습니다. </li><li> 100 bp DNA 사다리 14.4 μL와 SYBR Green 1.6 μL를 볼텍스를 사용하여 섞는다. </li><li> SGE 칩 ( 그림 2 )에서 아가로 오스 겔의 각 우물에 혼합물 4 μL를 적재하십시오. </li><li> SGE 칩의 두 차선에 전극을 놓습니다. </li><li> SGE 칩 위에 550 ~ 700 nm 밴드 패스 필터를 배치하십시오. </li><li> 전원을 켜십시오. 전기 전압을 180V (20V / cm)로 설정하십시오. 스마트 폰을 켜서 DNA 단편 분리 과정을 기록하십시오 ( 그림 3 ). </li><li> 10 분 후에 전기 영동이 끝나면 전원과 LED 표시등을 끕니다. </li><li> SGE 칩을 청소하십시오. </li></ol>

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이해 충돌이 선언되지 않습니다.

아가 로스 겔 전기 영동은 DNA, RNA 및 단백질 분리에 널리 사용됩니다. 이 연구는 전통적인 겔 전기 영동 프로토콜을 대체 할 새로운 방법을 제안합니다. 결과는 50, 100 및 1,000 bp DNA 사다리가 작은 조립 장치에서 잘 분리 될 수 있음을 보여줍니다. 이 방법의 가장 큰 장점은 거의 화학 물질을 소비하지 않고 핵산을 분리 할 수있을뿐만 아니라 분리 과정을 기록 할 수 있다는 것입니다. ...

<html> 슬랩 겔 전기 영동 (SGE)은 DNA 단편 분리 1 , 2 , 3 , 4 , 5 에 가장 효과적인 방법이며 따라서 생화학 및 생물학적 분석에서 다용도 도구로 간주됩니다 6 , 7 , 8 . 그러나 많은 실험에서 SGE가 다음 네 가지 문제에 의해 제한된다는 것을 나타냅니다. (1) 분리에는 수 시간이 걸리고 심지어 며칠이 걸립니다. (2) 화학 물질 소비가 매우 높다. (3) 복잡한 장치 ( 예 : 2D 전기 영동 세포, 전기 영동 전원 및 겔 이미징 시스템)가 필요합니다. (4) 겔 영상 시스템은 실험이 끝났을 때 분리 된 DNA 조각만을 관찰 할 수있다. 또한, SGE 9 에서 일반적으로 사용되는 ethidium bromide (EtBr)10 = 돌연변이 유발 및 암 유발 11,12 . 따라서 EtBr이 들어있는 젤을 나눠 줄 때는 항상 장갑을 착용해야합니다. 모세관 전기 영동 (CE)은 자동 작동, 짧은 분리 시간, 낮은 소비 등과 같은 SGE에 비해 13 , 14 , 15 , 16 , 17의 다양한 장점을 가지고 있습니다. 그러나 CE 장비는 꽤 비쌉니다. 따라서 이러한 한계를 극복하기 위해 DNA 분리를위한 시스템이 개발되었습니다 ( 그림 1 ). 이러한 시스템은 화학 물질 소비를 크게 줄이고 SGE 실험 시간 (8 분 미만)을 절약 할 수있을뿐만 아니라 스마트 폰을 통해 아가로 오스 겔에서 DNA 분리 과정을 실시간으로 추적 할 수도 있습니다. 이 프로토콜에 설명 된 절차를 따르면, 학생들은SGE 칩을 설계 및 제작하고, 칩에서 아가 로스 겔을 준비하고, 스마트 폰으로 간단한 SGE 시스템을 설치하고 아가로 오스 겔에서 DNA 이동 과정을 기록 할 수 있어야한다.

<table border="0" cellpadding="0" cellspacing="0" width="683">
	<tbody>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">10&#215;TBE</td>
			<td style="width:287px;">Beijing Solarbio Science &#38; Technology Co., Ltd.</td>
			<td style="width:181px;">T1051</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">50bp DNA ladder</td>
			<td style="width:287px;">Takara Bio Inc.</td>
			<td style="width:181px;">3421A</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">100bp DNA ladder</td>
			<td style="width:287px;">Takara Bio Inc.</td>
			<td style="width:181px;">3422A</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">1kbp DNA ladder</td>
			<td style="width:287px;">Takara Bio Inc.</td>
			<td style="width:181px;">3426A</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">SYBR GREEN</td>
			<td style="width:287px;">Takara Bio Inc.</td>
			<td style="width:181px;">5760A</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Agarose</td>
			<td style="width:287px;">Sigma-Aldrich Corporate</td>
			<td style="width:181px;">V900510</td>
		</tr>
	</tbody>
</table>

real-time tracking of dna fragment separation by smartphone

슬래브 겔 전기 영동 (SGE)은 DNA 단편을 분리하는 가장 일반적인 방법입니다. 따라서 그것은 생물학 및 다른 분야에 광범위하게 적용됩니다. 그러나 전통적인 SGE 프로토콜은 매우 지루하고 실험에 많은 시간이 걸립니다. 또한, SGE 실험에서 화학 물질 소비가 매우 높습니다. 이 연구는 SGE 칩을 기반으로 DNA 조각을 분리하는 간단한 방법을 제안한다. 이 칩은 조각 기계로 만든다. 두 개의 플라스틱 시트가 광 신호의 여기 및 방출 파장에 사용됩니다. DNA 밴드의 형광 신호는 스마트 폰으로 수집됩니다. 이 방법을 확인하기 위해 50, 100 및 1,000 bp DNA 사다리를 분리했습니다. 결과는 5,000 bp보다 작은 DNA 사다리가이 방법을 사용할 때 12 분 이내에 고해상도로 분석 할 수 있음을 보여 주며 전통적인 SGE 방법에 대한 이상적인 대체품임을 나타냅니다.

<html> 그림 4 , 그림 5 및 그림 6 은 50, 100 및 1,000 bp DNA 사다리의 겔 전기 영동 후 일반적인 결과를 나타냅니다. 실험 후, DNA 조각은 잘 분리되었다. 또한 동일한 샘플을 SGE 칩의 4 개 채널에서 분리하여 동일한 크기의 DNA 조각이 각 실험에서 동일한 거리로 이동 함을 보여줍니다. DNA 사다리의 분리 성능은 이동 거...

Watch this Scientific Journal Video about Real-time Tracking of DNA Fragment Separation by Smartphone at JoVE.com

Real-time Tracking of DNA Fragment Separation by Smartphone

Smartphone을 이용한 DNA 단편 분리 실시간 추적

전통적인 슬랩 젤 전기 영동 (SGE) 실험은 복잡한 장치와 높은 화학 물질 소비가 필요합니다. 이 연구는 단시간 내에 DNA 단편을 분리하는 저비용 방법을 설명하는 프로토콜을 제시합니다.

Slab gel electrophoresis (SGE) is the most common method for the separation of DNA fragments; thus, it is broadly applied to the field of biology and ...

real-time-tracking-of-dna-fragment-separation-by-smartphone

Research

JoVE Journal

Biochemistry

14.4K 조회수.  University of Shanghai for Science and Technology.  전통적인 슬랩 젤 전기 영동 (SGE) 실험은 복잡한 장치와 높은 화학 물질 소비가 필요합니다. 이 연구는 단시간 내에 DNA 단편을 분리하는 저비용 방법을 설명하는 프로토콜을 제시합니다. 

비디오: Real-time Tracking of DNA Fragment Separation by Smartphone

DNA Polymerase Activity Assay Using Near-infrared Fluorescent Labeled DNA Visualized by Acrylamide Gel Electrophoresis

For any enzyme, robust, quantitative methods are required for characterization of both native and engineered enzymes. For DNA polymerases, DNA synthesis can be characterized using an in vitro DNA synthesis assay followed by polyacrylamide gel electrophoresis. The goal of this assay is to quantify synthesis of both natural DNA and modified DNA (M-DNA). These approaches are particularly useful for resolving oligonucleotides with single nucleotide resolution, enabling observation of individual steps during enzymatic oligonucleotide synthesis. These methods have been applied to the evaluation of an array of biochemical and biophysical properties such as the measurement of steady-state rate constants of individual steps of DNA synthesis, the error rate of DNA synthesis, and DNA binding affinity. By using modified components including, but not limited to, modified nucleoside triphosphates (NTP), M-DNA, and/or mutant DNA polymerases, the relative utility of substrate-DNA polymerase pairs can be effectively evaluated. Here, we detail the assay itself, including the changes that must be made to accommodate nontraditional primer DNA labeling strategies such as near-infrared fluorescently labeled DNA. Additionally, we have detailed crucial technical steps for acrylamide gel pouring and running, which can often be technically challenging.

This protocol describes the characterization of DNA polymerase synthesis of modified DNA through observation of changes to near-infrared fluorescently labeled DNA using gel electrophoresis and gel imaging. Acrylamide gels are used for high resolution imaging of the separation of short nucleic acids, which migrate at different rates depending on size.

근 적외선 형광 레이블이 DNA 아크릴 아 미드 젤 전기 이동 법으로 시각을 사용 하 여 DNA 중 합 효소 활동 분석 결과

For any enzyme, robust, quantitative methods are required for characterization of both native and engineered enzymes. For DNA polymerases, DNA synthesis ...

연구

생화학

Regeneration of Arrayed Gold Microelectrodes Equipped for a Real-Time Cell Analyzer

The label-free cell-based assay is advantageous for biochemical study because of it does not require the use of experimental animals. Due to its ability to provide more dynamic information about cells under physiological conditions than classical biochemical assays, this label-free real-time cell assay based on the electric impedance principle is attracting more attention during the past decade. However, its practical utilization may be limited due to the relatively expensive cost of measurement, in which costly consumable disposable gold microchips are used for the cell analyzer. In this protocol, we have developed a general strategy to regenerate arrayed gold microelectrodes equipped for a commercial label-free cell analyzer. The regeneration process includes trypsin digestion, rinsing with ethanol and water, and a spinning step. The proposed method has been tested and shown to be effective for the regeneration and repeated usage of commercial electronic plates at least three times, which will help researchers save on the high running cost of real-time cell assays.

This protocol describes a general strategy to regenerate commercial arrayed gold microelectrodes equipped for a label-free cell analyzer aimed at saving on the high running costs ofmicrochip-based assays. The regeneration process includes trypsin digestion, rinsing with ethanol and water, and a spinning step, which enables repeated usage of microchips.

실시간 세포 분석기 장착 기준점과 골드 Microelectrodes의 재생

The label-free cell-based assay is advantageous for biochemical study because of it does not require the use of experimental animals. Due to its ability ...

Real-time Observation of the DNA Strand Exchange Reaction Mediated by Rad51

The DNA strand exchange reaction mediated by Rad51 is a critical step of homologous recombination. In this reaction, Rad51 forms a nucleoprotein filament on single-stranded DNA (ssDNA) and captures double-stranded DNA (dsDNA) non-specifically to interrogate it for a homologous sequence. After encountering homology, Rad51 catalyzes DNA strand exchange to mediate pairing of the ssDNA with the complementary strand of the dsDNA. This reaction is highly regulated by numerous accessary proteins in vivo. Although conventional biochemical assays have been successfully employed to examine the role of such accessory protein in vitro, kinetic analysis of intermediate formation and its progression into a final product has proven challenging due to the unstable and transient nature of the reaction intermediates. To observe these reaction steps directly in solution, fluorescence resonance energy transfer (FRET)-based real-time observation systems of this reaction were established. Kinetic analysis of real-time observations shows that the DNA strand exchange reaction mediated by Rad51 obeys a three-step reaction model involving the formation of a three-strand DNA intermediate, maturation of this intermediate, and the release of ssDNA from the mature intermediate. The Swi5-Sfr1 complex, an accessary protein conserved in eukaryotes, strongly enhances the second and third steps of this reaction. The FRET-based assays presented here enable us to uncover the molecular mechanisms through which recombination accessary proteins stimulate the DNA strand exchange activity of Rad51. The primary goal of this protocol is to enhance the repertoire of techniques available to researchers in the field of homologous recombination, particularly those working with proteins from species other than Schizosaccharomyces pombe, so that the evolutionary conservation of the findings presented herein can be determined.

Fluorescence resonance energy transfer-based real-time observation systems of the DNA strand exchange reaction mediated by Rad51 were developed. Using the protocols presented here, we are able to detect the formation of reaction intermediates and their conversion into products, while also analyzing the enzymatic kinetics of the reaction.

중재 Rad51 DNA 물가 교환 반응의 실시간 관찰

The DNA strand exchange reaction mediated by Rad51 is a critical step of homologous recombination. In this reaction, Rad51 forms a nucleoprotein filament ...

DNA Sequence Recognition by DNA Primase Using High-Throughput Primase Profiling

DNA primase synthesizes short RNA primers that initiate DNA synthesis of Okazaki fragments on the lagging strand by DNA polymerase during DNA replication. The binding of prokaryotic DnaG-like primases to DNA occurs at a specific trinucleotide recognition sequence. It is a pivotal step in the formation of Okazaki fragments. Conventional biochemical tools that are used to determine the DNA recognition sequence of DNA primase provide only limited information. Using a high-throughput microarray-based binding assay and consecutive biochemical analyses, it has been shown that 1) the specific binding context (flanking sequences of the recognition site) influences the binding strength of the DNA primase to its template DNA, and 2) stronger binding of primase to the DNA yields longer RNA primers, indicating higher processivity of the enzyme. This method combines PBM and primase activity assay and is designated as high-throughput primase profiling (HTPP), and it allows characterization of specific sequence recognition by DNA primase in unprecedented time and scalability.&#160;

Protein binding microarray (PBM) experiments combined with biochemical assays link the binding and catalytic properties of DNA primase, an enzyme that synthesizes RNA primers on template DNA. This method, designated as high-throughput primase profiling (HTPP), can be used to reveal DNA-binding patterns of a variety of enzymes.

고처리량 프리마제 프로파일링을 사용하여 DNA 프리마제에 의한 DNA 서열 인식

DNA primase synthesizes short RNA primers that initiate DNA synthesis of Okazaki fragments on the lagging strand by DNA polymerase during DNA replication. ...

Real-Time, Semi-Automated Fluorescent Measurement of the Airway Surface Liquid pH of Primary Human Airway Epithelial Cells

In recent years, the importance of mucosal surface pH in the airways has been highlighted by its ability to regulate airway surface liquid (ASL) hydration, mucus viscosity and activity of antimicrobial peptides, key parameters involved in innate defense of the lungs. This is of primary relevance in the field of chronic respiratory diseases such as cystic fibrosis (CF) where these parameters are dysregulated. While different groups have studied ASL pH both in vivo and in vitro, their methods report a relatively wide range of ASL pH values and even contradictory findings regarding any pH differences between non-CF and CF cells. Furthermore, their protocols do not always provide enough details in order to ensure reproducibility, most are low throughput and require expensive equipment or specialized knowledge to implement, making them difficult to establish in most labs. Here we describe a semi-automated fluorescent plate reader assay that enables the real-time measurement of ASL pH under thin film conditions that more closely resemble the in vivo situation. This technique allows for stable measurements for many hours from multiple airway cultures simultaneously and, importantly, dynamic changes in ASL pH in response to agonists and inhibitors can be monitored. To achieve this, the ASL of fully differentiated primary human airway epithelial cells (hAECs) are stained overnight with a pH-sensitive dye in order to allow for the reabsorption of the excess fluid to ensure thin film conditions. After fluorescence is monitored in the presence or absence of agonists, pH calibration is performed in situ to correct for volume and dye concentration. The method described provides the required controls to make stable and reproducible ASL pH measurements, which ultimately could be used as a drug discovery platform for personalized medicine, as well as adapted to other epithelial tissues and experimental conditions, such as inflammatory and/or host-pathogen models.

We present a protocol to make dynamic measurements of the airway surface liquid pH under thin film conditions using a plate-reader.

1 차 인간 기도 상피 세포의 기도 표면 액체 pH의 실시간 반 자동화 형광 측정

In recent years, the importance of mucosal surface pH in the airways has been highlighted by its ability to regulate airway surface liquid (ASL) ...

Monitoring GPCR-&#946;-arrestin1/2 Interactions in Real Time Living Systems to Accelerate Drug Discovery

Interactions between G-protein coupled receptors (GPCRs) and &#946;-arrestins are vital processes with physiological implications of great importance. Currently, the characterization of novel drugs towards their interactions with &#946;-arrestins and other cytosolic proteins is extremely valuable in the field of GPCR drug discovery particularly during the study of GPCR biased agonism. Here, we show the application of a novel structural complementation assay to accurately monitor receptor-&#946;-arrestin interactions in real time living systems. This method is simple, accurate and can be easily extended to any GPCR of interest and also it has the advantage that it overcomes unspecific interactions due to the presence of a low expression promoter present in each vector system. This structural complementation assay provides key features that allow an accurate and precise monitoring of receptor-&#946;-arrestin interactions, making it suitable in the study of biased agonism of any GPCR system as well as GPCR c-terminus &#8216;phosphorylation codes&#8217; written by different GPCR-kinases (GRKs) and post-translational modifications of arrestins that stabilize or destabilize the receptor-&#946;-arrestin complex.

GPCR-&#946;-arrestin interactions are an emerging field in GPCR drug discovery. Accurate, precise and easy to set up methods are necessary to monitor such interactions in living systems. We show a structural complementation assay to monitor GPCR-&#946;-arrestin interactions in real time living cells, and it can be extended to any GPCR.

약물 발견을 가속화하기 위해 실시간 생활 시스템에서 GPCR-β-arrestin1/2 상호 작용 모니터링

Interactions between G-protein coupled receptors (GPCRs) and &#946;-arrestins are vital processes with physiological implications of great importance. ...

Measuring Nucleotide Binding to Intact, Functional Membrane Proteins in Real Time

We have developed a method to measure binding of adenine nucleotides to intact, functional transmembrane receptors in a cellular or membrane environment. This method combines expression of proteins tagged with the fluorescent non-canonical amino acid ANAP, and FRET between ANAP and fluorescent (trinitrophenyl) nucleotide derivatives. We present examples of nucleotide binding to ANAP-tagged KATP ion channels measured in unroofed plasma membranes and excised, inside-out membrane patches under voltage clamp. The latter allows for simultaneous measurements of ligand binding and channel current, a direct readout of protein function. Data treatment and analysis are discussed extensively, along with potential pitfalls and artefacts. This method provides rich mechanistic insights into the ligand-dependent gating of KATP channels and can readily be adapted to the study of other nucleotide-regulated proteins or any receptor for which a suitable fluorescent ligand can be identified.

This protocol presents a method for measuring adenine nucleotide binding to receptors in real time in a cellular environment. Binding is measured as F&#246;rster resonance energy transfer (FRET) between trinitrophenyl nucleotide derivatives and protein labeled with a non-canonical, fluorescent amino acid.

온전한 기능성 막 단백질에 대한 뉴클레오티드 결합을 실시간으로 측정

We have developed a method to measure binding of adenine nucleotides to intact, functional transmembrane receptors in a cellular or membrane environment. ...

Enabling Real-Time Compensation in Fast Photochemical Oxidations of Proteins for the Determination of Protein Topography Changes

Fast photochemical oxidation of proteins (FPOP) is a mass spectrometry-based structural biology technique that probes the solvent-accessible surface area of proteins. This technique relies on the reaction of amino acid side chains with hydroxyl radicals freely diffusing in solution. FPOP generates these radicals in situ by laser photolysis of hydrogen peroxide, creating a burst of hydroxyl radicals that is depleted on the order of a microsecond. When these hydroxyl radicals react with a solvent-accessible amino acid side chain, the reaction products exhibit a mass shift that can be measured and quantified by mass spectrometry. Since the rate of reaction of an amino acid depends in part on the average solvent accessible surface of that amino acid, measured changes in the amount of oxidation of a given region of a protein can be directly correlated to changes in the solvent accessibility of that region between different conformations (e.g., ligand-bound versus ligand-free, monomer vs. aggregate, etc.) FPOP has been applied in a number of problems in biology, including protein-protein interactions, protein conformational changes, and protein-ligand binding. As the available concentration of hydroxyl radicals varies based on many experimental conditions in the FPOP experiment, it is important to monitor the effective radical dose to which the protein analyte is exposed. This monitoring is efficiently achieved by incorporating an inline dosimeter to measure the signal from the FPOP reaction, with laser fluence adjusted in real-time to achieve the desired amount of oxidation. With this compensation, changes in protein topography reflecting conformational changes, ligand-binding surfaces, and/or protein-protein interaction interfaces can be determined in heterogeneous samples using relatively low sample amounts.

Fast photochemical oxidation of proteins is an emerging technique for the structural characterization of proteins. Different solvent additives and ligands have varied hydroxyl radical scavenging properties. To compare the protein structure in different conditions, real-time compensation of hydroxyl radicals generated in the reaction is required to normalize reaction conditions.

단백질 지형 변화의 측정을 위한 단백질의 빠른 광화학 산화에 실시간 보상 가능하게

Fast photochemical oxidation of proteins (FPOP) is a mass spectrometry-based structural biology technique that probes the solvent-accessible surface area ...

Workflow and Tools for Crystallographic Fragment Screening at the Helmholtz-Zentrum Berlin

Fragment screening is a technique that helps to identify promising starting points for ligand design. Given that crystals of the target protein are available and display reproducibly high-resolution X-ray diffraction properties, crystallography is among the most preferred methods for fragment screening because of its sensitivity. Additionally, it is the only method providing detailed 3D information of the binding mode of the fragment, which is vital for subsequent rational compound evolution. The routine use of the method depends on the availability of suitable fragment libraries, dedicated means to handle large numbers of samples, state-of-the-art synchrotron beamlines for fast diffraction measurements and largely automated solutions for the analysis of the results.
Here, the complete practical workflow and the included tools on how to conduct crystallographic fragment screening (CFS) at the Helmholtz-Zentrum Berlin (HZB) are presented. Preceding this workflow, crystal soaking conditions as well as data collection strategies are optimized for reproducible crystallographic experiments. Then, typically in a one to two-day procedure, a 96-membered CFS-focused library provided as dried ready-to-use plates is employed to soak 192 crystals, which are then flash-cooled individually. The final diffraction experiments can be performed within one day at the robot-mounting supported beamlines BL14.1 and BL14.2 at the BESSY&#160; II electron storage ring operated by the HZB in Berlin-Adlershof (Germany). Processing of the crystallographic data, refinement of the protein structures, and hit identification is fast and largely automated using specialized software pipelines on dedicated servers, requiring little user input.
Using the CFS workflow at the HZB enables routine screening experiments. It increases the chances for successful identification of fragment hits as starting points to develop more potent binders, useful for pharmacological or biochemical applications.

Crystallographic fragment screening at the Helmholtz-Zentrum Berlin is performed using a workflow with dedicated compound libraries, crystal handling tools, fast data collection facilities&#160;and largely automated data analysis. The presented protocol intends to maximize the output of such experiments to provide promising starting points for downstream structure-based ligand design.

헬름홀츠 젠트럼 베를린에서 결정화 조각 검사를 위한 워크플로우 및 도구

Fragment screening is a technique that helps to identify promising starting points for ligand design. Given that crystals of the target protein are ...

Deciphering Molecular Mechanism of Histone Assembly by DNA Curtain Technique

Chromatin is a higher-order structure that packages eukaryotic DNA. Chromatin undergoes dynamic alterations according to the cell cycle phase and in response to environmental stimuli. These changes are essential for genomic integrity, epigenetic regulation, and DNA metabolic reactions such as replication, transcription, and repair. Chromatin assembly is crucial for chromatin dynamics and is catalyzed by histone chaperones. Despite extensive studies, the mechanisms by which histone chaperones enable chromatin assembly remains elusive. Moreover, the global features of nucleosomes organized by histone chaperones are poorly understood. To address these problems, this work describes a unique single-molecule imaging technique named DNA curtain, which facilitates the investigation of the molecular details of nucleosome assembly by histone chaperones. DNA curtain is a hybrid technique that combines lipid fluidity, microfluidics, and total internal reflection fluorescence microscopy (TIRFM) to provide a universal platform for real-time imaging of diverse protein-DNA interactions.Using DNA curtain, the histone chaperone function of Abo1, the Schizosaccharomyces pombe bromodomain-containing AAA+ ATPase, is investigated, and the molecular mechanism underlying histone assembly of Abo1 is revealed. DNA curtain provides a unique approach for studying chromatin dynamics.

DNA curtain, a high-throughput single-molecule imaging technique, provides a platform for real-time visualization of diverse protein-DNA interactions. The present protocol utilizes the DNA curtain technique to investigate the biological role and molecular mechanism of Abo1, a Schizosaccharomyces pombe bromodomain-containing AAA+ ATPase.

DNA 커튼 기법에 의한 히스톤 조립의 분자 메커니즘 해독

Chromatin is a higher-order structure that packages eukaryotic DNA. Chromatin undergoes dynamic alterations according to the cell cycle phase and in ...