What are the recommended conditions for proteolytic digestions using Protease S. aureus V8 (Endoproteinase-Glu-C) ?
Protease S. aureus V8 (Endoproteinase-Glu-C) specifically cleaves peptide bonds on the COOH-terminal side of either aspartic or glutamic acids. In the presence of ammonium, the enzyme specificity is preferential to glutamic sites. It has a molecular weight of 27,000 daltons and optimum pH's of 4.0 and 7.8 with hemoglobin as the substrate. Protease S. aureus V8 is inhibited by diisopropylfluorophosphate and monovalent anions such as F-, Cl-, CH3COO- and NO3.
Typically STAP is used at low enzyme/protein ratio ranges 1:10 to 1:50 and incubated for several hours (2-48hrs) at 37C in ammonium buffers (pH range 4-8).