Endoproteinase Glu-C, also known an V8, is a serine endoproteinase that is isolated from Staphylococcus aureus V8. Endoproteinase Glu-C is highly purified, resulting in a product suitable for proteomics work.
The specificity of Glu-C is primarily determined by the buffer pH and composition. In ammonium biocarbonate buffer (pH 7.8), Glu-C preferentially cleaves glutamyl bonds. In phosphate buffers (pH 7.8), Glu-C will cleave at both glutamyl and aspartyl bonds.
However, the presence of a proline residue on the carboxy side of the bond inhibits cleavage. Glu-C is used in proteomics for peptide mapping and protein sequence work due to its highly specific cleavage of peptides resulting in a limited number of fragments.