Calcium-dependent hydrolases mechanism

These three catalytic functionalities are similar in practically all hydrolytic enzymes, but the actual functional groups performing the reactions differ among hydrolases. Based on the structures of their catalytic sites, hydrolases can be divided into five classes, namely serine hydrolases, threonine hydrolases, cysteine hydrolases, aspartic hydrolases, and metallohydrolases, to which the similarly acting calcium-dependent hydrolases can be added. Hydrolases of yet unknown catalytic mechanism also exist. 

Thus, calcium-dependent hydrolases show clear structural and catalytic similarities with metallohydrolases, both in the role played by a divalent cation and in the mechanism of H20 activation. 

Jakubowski, H. (2000). Calcium-dependent human serum homocysteine thiolactone hydrolase. A protective mechanism against protein N-homocysteinylation. J. Biol. Chem. 275 3957-62. 

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