Enzymes in Mass Spectrometry
Trypsin, MS approved is especially designed for digestion of proteins prior to mass spectrometry analysis. Every lot is approved for use in in-gel digestion and mass spectrometry analysis. Reductive methylation of the lysine residues of trypsin results in a stable product that is extremely resistant to autolytic degradation. Trypsin, MS approved is purified by chromatography. No chymotryptic activity is detectable.
Endoproteinase Glu-C, recombinant (V8) is a serine endoproteinase used with in-gel digestion and mass spectrometric analysis. The specificity of Glu-C is primarily determined by the buffer pH and composition. Using phosphate buffers (pH 7.8), Glu-C will cleave at both glutamyl and aspartyl bonds. Ammonium bicarbonate buffer (pH 7.8) will lead to a preferential cleavage of glutamyl bonds. The presence of proline residues on the carboxy side of the peptide bond inhibits the cleavage. Due to its highly specific cleavage of peptides Glu-C is used in proteomics for peptide mapping and protein sequence work.
Lysyl Endopeptidase® is especially designed for use with in-gel digestion and mass spectrometric analysis. Lysyl Endopeptidase (LysC), originally isolated from the soil bacterium discovered by Masaki, et al. cleaves specifically the peptide bonds at the carboxy-terminal side of Lysine residues and S-aminoethylcysteine residues with a high degree of specificity, making it a valuable tool for protein sequence analysis and for proteome research. An added feature of Lysyl Endopeptidase is its ability to retain complete activity after incubation in 4 M urea or in 0.1 % SDS solution for up to 6 hours at 30 °C.