Protein Analysis FAQ

• • What Are the Functions of Histone Modifications

  Histone modifications play a critical role in regulating gene expression as well as influencing the structural and functional organization of DNA within chromatin. These modifications commonly include acetylation, methylation, phosphorylation, and ubiquitination. They can alter the charge properties of histones, thereby affecting their interaction with DNA and the binding affinity of various non-coding proteins to histones. 1. Acetylation typically occurs on lysine residues of histone proteins. This .......

• • How to Determine the Injection Volume for Column Chromatography Analysis

  Chromatography is an analytical technique employed to separate and quantitatively analyze components within complex mixtures. In chromatographic analysis, the injection volume represents a critical parameter, as it directly influences the sensitivity, reproducibility, and accuracy of the results. The following recommendations are provided for determining an appropriate injection volume: 1. Refer to the Manufacturer’s Recommended Range Chromatographic columns vary in their tolerance and performance with.....

• • How to Detect Protein Expression in Western Blot Experiments

  Detection of protein expression in Western Blot (WB) experiments: Sample Preparation 1. Extract total proteins from the cells or tissues of interest. 2. Quantify the extracted proteins and prepare them in loading buffer suitable for SDS-PAGE analysis. SDS-PAGE Gel Electrophoresis 1. Select an appropriate gel concentration based on the molecular weight of the target protein and cast the gel accordingly. 2. Load equal amounts of protein per lane and perform SDS-PAGE to separate proteins by molecular weight.

• • What Are the Western Blot Experimental Techniques and Common Problem Analysis

  Western blot (WB), also known as protein immunoblotting, is a widely applied technique in molecular biology for detecting the presence and quantity of specific proteins within complex protein mixtures. The following outlines the fundamental steps of the WB procedure and discusses common issues that may arise during the experiment. Technical Procedures 1. Sample Preparation Total proteins are extracted from cells or tissues. 2. Gel Electrophoresis Proteins are separated by molecular weight using SDS-PAGE.

• • What Sugar Appears When Mannose and Rhamnose Co-elute in HPLC Monosaccharide Analysis

  Elution Behavior of Mannuronic Acid Mannuronic acid is an acidic monosaccharide that typically exhibits a longer retention time than neutral monosaccharides. Under standard HPLC conditions, it generally elutes after mannose and rhamnose. However, its exact retention time can vary depending on parameters such as column type, mobile phase composition, and pH. Specifically: On amino columns (NH₂ columns), mannuronic acid typically elutes within 10–20 minutes. On reversed-phase columns (C18 columns), when a....

• • Is There a Protocol for Protein Crosslinking

  The following is a commonly used protocol for protein crosslinking. Specific procedures may require optimization depending on the properties of the protein and the selected crosslinking reagent. 1. Preparation of the Crosslinker Select an appropriate crosslinking reagent (e.g., glutaraldehyde, BS3), and prepare a working solution at the desired concentration according to the manufacturer’s instructions. 2. Protein Dissolution Dissolve the target protein in a suitable buffer, typically PBS or HEPES, at a....

• • What Software Can Be Used to Analyze Circular Dichroism Results

  Circular dichroism (CD) results can be analyzed using various software tools. Below are several widely adopted options: 1. CDPro CDPro is a widely used software suite for circular dichroism data analysis, comprising three main algorithms: CONTIN, SELCON3, and CDSSTR. CONTIN and SELCON3 estimate protein secondary structure by comparing CD spectra against reference datasets derived from proteins of known structure, even in cases where the structure of the target protein is unknown. CDSSTR employs a ..........

• • What Reagents Are Required for In Vitro Cross-Linking of Two Purified Proteins

  Chemical cross-linkers are commonly employed for in vitro protein cross-linking. The choice of reagent depends on the characteristics of the proteins involved and the specific goals of the experiment. Commonly used protein cross-linkers include: 1. BS3 (Bis(sulfosuccinimidyl)suberate) BS3 is a water-soluble cross-linker that targets lysine residues for cross-linking. 2. DSS (Disuccinimidyl suberate) DSS is structurally similar to BS3 but is water-insoluble, making it suitable for non-aqueous environments.

• • What Are the Solutions to the Problem That Proteins Are Always Adsorbed on Membranes

  Protein adsorption on membranes is a common problem, especially when using membranes for sample processing or protein filtration. Here are several solutions for your reference: 1. Application of Blocking Agents Protein blocking agents (e.g., bovine serum albumin, BSA) can be added to the sample prior to filtration. These agents occupy potential binding sites on the membrane surface, thereby minimizing nonspecific adsorption of target proteins. 2. Adjustment of Buffer Conditions Modulating the buffer's pH...

• • How to Verify a Peptide After Synthesis and Function Prediction

  Verification following synthesis and functional prediction can be conducted from the following perspectives: Peptide Identification 1. Mass Spectrometry (MS): Applied to determine the molecular weight of the peptide and confirm whether the synthesized peptide corresponds to the predicted sequence. 2. Amino Acid Sequence Analysis: Tandem mass spectrometry (MS/MS) is used to analyze the amino acid sequence of the peptide, ensuring the sequence is accurate and complete. 3. High-Performance Liquid ........