Protein Analysis FAQ

• • What Are the Methods for Measuring Peptide Molecular Weight Distribution

  The primary methods for determining peptide molecular weight distribution include: Mass Spectrometry (MS) 1. Characteristics As the most commonly employed technique, mass spectrometry enables precise measurement of peptide mass and sequence identification based on peptide fragmentation patterns. It offers high sensitivity, high resolution, and high throughput, while requiring only minimal sample quantities. 2. Applications MS is well-suited for analyzing the molecular weights of complex polypeptide.........

• • Experimental Steps of Mitochondrial Proteomics Analysis

  Mitochondrial proteomics analysis is a vital experimental technique for investigating the types, expression levels, and functions of proteins within mitochondria. The general steps involved in this analysis are summarized below: Sample Preparation 1. Selection of Cells or Tissues Mitochondria are isolated from specific cell lines or tissues, selected according to the experimental objectives, such as heart, liver, or brain. 2. Cell Disruption Cells or tissues are disrupted using mechanical or chemical.......

• • Steps for BS3 Crosslinking

  The process of BS3 crosslinking generally involves the following key steps: 1. Sample Preparation Begin by preparing the protein samples intended for crosslinking. The protein concentration should be properly adjusted, and the sample must be maintained in a compatible buffer system. 2. Preparation of BS3 Solution Dissolve BS3 in an appropriate solvent, such as DMSO or water, to achieve the desired working concentration. 3. Addition of BS3 to the Sample Introduce the prepared BS3 solution into the protein...

• • Blue Native PAGE Protocol

  The experimental procedure for Blue Native PAGE (BN-PAGE) mainly involves the following steps: 1. Sample Preparation Cells are lysed using mild detergents, such as digitonin or n-dodecyl β-D-maltoside, at 4°C to isolate protein complexes for subsequent analysis. 2. Protein Extraction Cellular debris and remnants are removed by centrifugation, and the resulting supernatant, containing the protein extract, is collected. 3. Sample Buffering The protein sample is mixed with an appropriate amount of G-250 dye...

• • What Software Is Generally Used to Process Polypeptide Mass Spectrometry Data

  The following software tools are commonly used to process polypeptide mass spectrometry data: 1. MaxQuant MaxQuant is a comprehensive mass spectrometry data analysis platform specifically developed for proteomic studies, supporting both polypeptide identification and quantification. It is particularly well-suited for high-resolution MS data and features integrated support for isotopic labeling as well as label-free quantification (LFQ) methodologies. 2. Proteome Discoverer Proteome Discoverer, developed....

• • How to Determine Protein Size Based on the Gel

  During SDS-PAGE, a molecular weight marker—comprising a set of proteins with known molecular weights—is typically loaded into one lane of the gel. After electrophoresis, these standard proteins produce a series of bands, each corresponding to a specific molecular weight. The sample and the molecular weight marker are run simultaneously in SDS-PAGE. Upon completion of electrophoresis, the migration position of the sample band on the gel is observed and compared with the bands of the adjacent molecular.......

• • Why Does the Protein Band Broaden After Moving from Stacking to Separating Gel in SDS-PAGE

  In the process of SDS-PAGE electrophoresis, protein samples are first loaded onto the stacking gel and then migrate into the separating gel. These two types of gels serve different functions and possess distinct physicochemical properties: 1. Stacking Gel This gel is characterized by a low polyacrylamide concentration and relatively large pore size. It does not separate proteins based on molecular weight. Instead, its primary function is to concentrate all proteins into a sharply focused zone, thereby......

• • Classification of Serotonylated Histones Within Post-Translational Modification Types

  5-hydroxytryptamine (5-HT, also known as serotonin) modification of histones is classified as serotonylation, a distinct form of post-translational modification (PTM) that has gained increasing attention in recent years. Serotonylation involves the covalent attachment of serotonin molecules to specific amino acid residues on proteins, such as the formation of an amide bond with glutamate residues. This type of modification plays a role in regulating various physiological processes in living organisms.......

• • What Is Species Variation in Proteins

  Species variation in proteins refers to differences in protein sequences, structures, and functions across different species or populations. These variations arise through evolutionary processes and reflect both the phylogenetic relationships among species and their adaptive strategies to distinct environments. Species Variation in Protein Sequences Each species possesses a unique genome, and the proteins encoded by these genes often differ in their amino acid sequences from those of other species.

• • Desalting Following Protein Separation and Purification: Where Do These Salts Originate

  Desalting is frequently required following protein separation and purification. The salts present at this stage primarily originate from endogenous ions within biological systems (e.g., Na⁺, K⁺, Cl⁻), buffer salts used in extraction solutions, salts contained in elution buffers, and ionic components introduced by certain denaturants. Elevated salt concentrations can adversely impact protein activity, stability, and interactions with other molecules. Moreover, residual salts may interfere with downstream....