Common Proteases Used in Protein Sequencing
Protein sequencing is the process of analyzing the amino acid sequence of proteins, where commonly used proteases play a crucial role. Below is a detailed introduction to some commonly used proteases:
1. Trypsin
1. Cleavage Sites:
Trypsin specifically cleaves at the carboxyl side of lysine (K) and arginine (R).
2. Characteristics:
Trypsin is one of the most commonly used proteases because its cleavage sites are prevalent, and it produces peptide fragments of moderate length, which are convenient for subsequent analysis.
3. Applications:
Widely used in mass spectrometry analysis and Edman degradation for protein sequencing.
2. Chymotrypsin
1. Cleavage Sites:
Chymotrypsin cleaves at the carboxyl side of tyrosine (Y), phenylalanine (F), and tryptophan (W).
2. Characteristics:
It has broader cleavage site selectivity than trypsin, providing different peptide information.
3. Applications:
Often used in conjunction with trypsin to obtain more sequence information.
3. Pepsin
1. Cleavage Sites:
Pepsin is most active under acidic conditions and preferentially cleaves the amino side of hydrophobic and aromatic amino acids (such as F, L, W, and Y).
2. Characteristics:
Highly active at low pH (pH 1.5-2.5), suitable for processing proteins unstable under other enzymatic conditions.
3. Applications:
Commonly used for specific domain or secondary structure analysis.
4. Glu-C (V8 Protease)
1. Cleavage Sites:
Glu-C specifically cleaves at the carboxyl side of glutamic acid (E).
2. Characteristics:
Highly specific for glutamic acid, ideal for analyzing proteins rich in glutamic acid.
3. Applications:
Used for analyzing protein sequences with abundant glutamic acid.
5. Proteinase K
1. Cleavage Sites:
Proteinase K can act on various peptide bonds, with broad substrate specificity.
2. Characteristics:
Highly efficient at degrading denatured proteins, commonly used to remove protein contaminants from samples.
3. Applications:
Frequently used in nucleic acid extraction processes to digest proteins in samples, ensuring high-purity DNA or RNA is obtained.
6. Lysyl Endopeptidase
1. Cleavage Sites:
Lysyl Endopeptidase specifically cleaves at the carboxyl side of lysine (K).
2. Characteristics:
High specificity for cleavage, producing peptides suitable for mass spectrometry analysis.
3. Applications:
Often used in protein mass spectrometry analysis, in combination with trypsin for more detailed sequence information.
Each of these proteases has its unique cleavage characteristics and application scenarios. Researchers can choose appropriate proteases for protein sequencing based on different research objectives. These tools provide scientists with diverse means to analyze complex protein sequences.
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Related Services:
Protein N/C-terminal sequencing
Biopharmaceutical N/C-terminal sequencing
N-terminal protein sequencing based on Edman degradation
Top-down protein sequencing method
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