Family S81
Summary for family S81
| Family type peptidase | S81.001 - destabilase (Hirudo medicinalis), MEROPS Accession MER0003393 (peptidase unit: 23-133) |
| Content of family | Family S81 contains isopeptidases. |
| History |
Identifier created: MEROPS 9.8 (17 December 2012)
Family S81 contains the bifunctional enzyme destabilase (S81.001) from the medicinal leech (Hirudo medicinalis) and other invertebrates. The family is also known as 'i-lyz' for 'invertebrate lysozyme'. |
| Catalytic type | Serine |
| Active site residues | S49 K58 |
| Active site | Destabilase has two active sites each with a different catalytic activity, that of a lysozyme and that of an isopeptidase. Mutagenesis studies have shown that the lysozyme activity is dependent upon Glu14 and Asp26, whereas the isopeptidase activity requires a serine/lysine catalytic dyad, namely Ser29 and Lys38 (Zavalova et al., 2012). |
| Activities and specificities | As a lysozyme, destabilase cleaves the beta-(1,4)-glycosidic bond between N-acetylmuramic acid and N-acetylglucosamine of the peptidoglycan of bacterial cell walls. The isopeptidase activities include hydrolysing epsilon-(gamma-Glu)-Lys crosslinks between Glu and Lys in a stabilized fibrin (Baskova & Nikonov, 1991) and similar isopeptide bonds found in the cross-linking peptide of peptidoglycan in bacterial cell walls (Joskova et al., 2009). |
| Molecular structure | The tertiary structure of lysozyme from Tapes japonica has been determined, and shows that the enzyme exists at low salt concentrations as a dimer. At high salt concentrations, monomers form and the chitinase activity increases (Goto et al., 2007). |
| Clan | unassigned |
