BIOCHEMICAL-PROPERTIES OF STAPHYLOCOCCAL (PHOSPHO)LIPASES

Various staphylococci secrete lipases which require calcium ions for a ctivity, and have profound preferences for substrates with different c hain lengths. The lipase from Staphylococcus hyicus is exceptional sin ce it has higher phospholipase than lipase activity. This paper gives an overview of the biochemical properties: of these enzymes. It appear s that chain length selectivity of these enzymes resides in the acylat ion step. Interfaces mainly influence the acylation step. Calcium ions do not influence the rate of acylation or deacylation although stabil ise the enzyme against denaturation. Molecular modelling based on the X-ray structure of Pseudomonas glumae lipase was used to construct a m odel of the staphylococcal lipases. With this model the position of se rveral residues involved in stubstrate selectivity was predicted. More over, a sequence element could be assigned that may function as the so -called lid domain in staphylococcal lipases. Sequence alignment of fo ur staphylococcal lipases, and lipases from P. glumae and Bacillus the rmocatenulatus identified several potential calcium ligands, one of wh ich was verified by site directed mutagensesis. It is concluded that s tabilisation of lipases by calcium ions might be a more general phenom enon than recognized so far. (C) 1998 Elsevier Science Ireland Ltd. Al l rights reserved.