Chymase, a chymotryptic serine proteinase that belongs to the peptidase family S1, is an enzyme that in humans is encoded by the CMA1 gene.
Chymases (EC , mast cell protease 1, skeletal muscle protease, skin chymotryptic proteinase, mast cell serine proteinase, skeletal muscle protease) are a family of serine proteases found primarily in mast cells, though also present in basophil granulocytes (e.g. alpha chymase mcpt8). CMA1 Serine proteases (or serine endopeptidases) are enzymes that cleave peptide bonds in proteins, in which serine serves as the nucleophilic amino acid at the (enzyme's) active site. The majority belong to the S1 family of the PA clan (superfamily) of proteases. 
