Staphylococcus aureus V8 protease （Endoproteinase Glu-C） belongs to the serine protease family and can specifically hydrolyze carboxy-terminal peptide bonds of glutamic acid （Glu） or aspartate （Asp） residues. Its specificity is directly affected by the composition of the buffer, recognizing and cutting Glu carboxy-terminal peptide bonds in NH4HCO3 of pH7.8 and CH3COONH4 of pH4.0, recognizing and cutting Glu or Asp carboxy-terminal peptide bonds in phosphate buffers of pH7.8，but the hydrolysis rate of Glu was higher than that of Asp. Glu-C has been reported to be active in 0.2% SDS （sodium lauryl sulfate） and 4.0M urea.