Sedolisin

The sedolisin (MEROPS S53) family of peptidases are a family of serine proteases structurally related to the subtilisin (S8) family. Well-known members of this family include sedolisin ("pseudomonalisin") found in Pseudomonas bacteria, xanthomonalisin ("sedolisin-B"), 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.^[1]

S8/S53 domain
Structure of pseudomonalisin (PDB: 1GA6​)
Identifiers
Symbol	Peptidase_S8
Pfam	PF00082
InterPro	IPR000209
PROSITE	PDOC00125
CATH	1GA6
SCOP2	1GA6 / SCOPe / SUPFAM
CDD	cd07477
Available protein structures: Pfam   structures / ECOD   PDB RCSB PDB; PDBe; PDBj PDBsum structure summary

Their optimal pH is around 3. Most members of the family are produced as a precursor protein with N-terminal (InterPro: IPR015366) and sometimes C-terminal peptides that need to be cleaved off.^[2]

Family members

Sedolisin

Sedolisin
Identifiers
EC no.	3.4.21.100
CAS no.	848318-58-1
Databases
IntEnz	IntEnz view
BRENDA	BRENDA entry
ExPASy	NiceZyme view
KEGG	KEGG entry
MetaCyc	metabolic pathway
PRIAM	profile
PDB structures	RCSB PDB PDBe PDBsum
Search PMC articles PubMed articles NCBI proteins

Sedolisin (P42790, pseudomonapepsin, sedolysin) 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(NO₂)-Arg-Leu.^[3][4][5][6]

Xanthomonalisin

Xanthomonalisin
Identifiers
EC no.	3.4.21.101
CAS no.	113356-29-9
Databases
IntEnz	IntEnz view
BRENDA	BRENDA entry
ExPASy	NiceZyme view
KEGG	KEGG entry
MetaCyc	metabolic pathway
PRIAM	profile
PDB structures	RCSB PDB PDBe PDBsum
Search PMC articles PubMed articles NCBI proteins

Xanthomonalisin (Q60106) is found in Xanthomonas bacteria. It cleaves caesin and clots milk.^[7][8]

Physarolisin

Physarolisin
Identifiers
EC no.	3.4.21.103
CAS no.	94949-28-7
Databases
IntEnz	IntEnz view
BRENDA	BRENDA entry
ExPASy	NiceZyme view
KEGG	KEGG entry
MetaCyc	metabolic pathway
PRIAM	profile
PDB structures	RCSB PDB PDBe PDBsum
Search PMC articles PubMed articles NCBI proteins

Physarolisin (Q8MZS4, physaropepsin) is a milk-clotting enzyme. It shows preferential cleavage of Gly⁸-Ser in B chain of insulin most rapidly, followed by Leu¹¹!Val, Cys(SO₃H)¹⁹-Gly and Phe²⁴-Phe.^{[9][10][11][12][13]}

It is special in that it is cold-adapted. It was discovered in the slime mold Physarum flavicomum. Similar proteins (InterPro: IPR017001) are also found in archaea.^[14]