There are about 40 families of serine proteases defined by amino acid sequence similarities that can be further grouped into 7 clans on the basis of their tertiary structure and the order of the catalytic triad.1 Members of clans SA and SB are characterized by the presence of calcium ions that stabilize the structure against proteolysis and thermal denaturation, but are not involved in catalysis or substrate recognition. Clan SA, which includes trypsin-like proteases, and clan SB, which includes subtilisins, are examples of proteins that are stabilized by the presence of calcium. Members of each enzyme family bind calcium in different ways with the same end result, stabilization of the tertiary structure.
Citation: Handbook of Metalloproteins
Publisher Info: John Wiley & Sons, Ltd, Hoboken, NJ
Pub Type: Books
calcium-binding, endopepidase, hydrolase, non-structural calcium, serine protease, structural stability, subtilisin, trypsin