Sedolisin


The sedolisin family of peptidases are a family of serine proteases structurally related to the subtilisin family. Well-known members of this family include sedolisin found in Pseudomonas bacteria, xanthomonalisin, physarolisin as well as animal tripeptidyl peptidase I. It is also known as sedolysin or serine-carboxyl peptidase. This group of enzymes contains a variation on the catalytic triad: unlike S8 which uses Ser-His-Asp, this group runs on Ser-Glu-Asp, with an additional acidic residue Asp in the oxyanion hole.
Their optimal pH is around 3. Most members of the family are produced as a precursor protein with N-terminal and sometimes C-terminal peptides that need to be cleaved off.

Family members

Sedolisin

Sedolisin is a serine protease. It is secreted by Pseudomonas sp. 101. It performs hydrolysis of the B chain of insulin at -Glu13-Ala-, -Leu15-Tyr- and -Phe25-Tyr-, and angiotensin I at -Tyr4-Ile-. A good synthetic substrate is Lys-Pro-Ile-Glu-Phe-Phe-Arg-Leu.

Xanthomonalisin

Xanthomonalisin is found in Xanthomonas bacteria. It cleaves caesin and clots milk.

Physarolisin

Physarolisin is a milk-clotting enzyme. It shows preferential cleavage of Gly8-Ser in B chain of insulin most rapidly, followed by Leu11!Val, Cys19-Gly and Phe24-Phe.
It is special in that it is cold-adapted. It was discovered in the slime mold Physarum flavicomum. Similar proteins are also found in archaea.