Proteinase K, Molecular Biology Grade, >30 units/mg proteinProteinase K (Endopeptidase K) is a stable and highly reactive serine protease. Evidence from crystal and molecular structure studies indicates the enzyme belongs to the subtilisin family with an active site catalytic triad (Asp39 His69 Ser224). It remains stable and active in the presence of chemicals that usually denature proteins, such as SDS and urea, chelating agents such as EDTA, sulfhydryl reagents, as well as trypsin or chymotrypsin