Enzymes in Mass Spectrometry
Trypsin MS approved is suitable for digestion of proteins for 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. Every lot is approved for use in in-gel digestion and mass spectrometry analysis. Specificity verified by digestion of oxidized B-chain of insulin. A Trypsin Peptide (TP) Standard is available separately (cat. no. 37285) allowing internal calibration for enhancing mass accuracy. The TP standard provides tryptic activity to generate masses m/z 842 and 2211.
Endoproteinase Glu-C (V8) is a serine endoproteinase isolated from Staphylococcus aureus V8. Approved quality for use 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.