Destabilase from the medicinal leech is a representative of a novel familyof lysozymes

Intrinsic lysozyme-like activity was demonstrated for destabilase from the medicinal leech supported by (1) high specific lysozyme activity of the hig hly purified destabilase, (2) specific inhibition of the lysozyme-like acti vity by anti-destabilase antibodies, and (3) appreciable lysozyme-like acti vity in insect cells infected with recombinant baculoviruses carrying cDNAs encoding different isoforms of destabilase. Several isoforms of destabilas e constitute a protein family at least two members of which are characteriz ed by lysozyme activity. The corresponding gene family implies an ancient e volutionary history of the genes although the function(s) of various lysozy mes in the leech remains unclear. Differences in primary structures of the destabilase family members and members of known lysozyme families allow one to assign the former to a new family of lysozymes. New proteins homologous to destabilase were recently described for Caenorhabditis elegans and biva lve mollusks suggesting that the new lysozyme family can be widely distribu ted among invertebrates. It remains to be investigated whether the two enzy matic activities (isopeptidase and lysozyme-like) are attributes of one and the same protein. (C) 2000 Published by Elsevier Science B.V. All rights r eserved.