Some Characteristics of Phospholipase C from Bacillus cereus

Abstract

The amino acid composition of purified Bacillus cereus phospholipase C is reported. The enzyme contains one methionine residue and two fragments are obtained after cyanogen bromide cleavage. The sequence of the amino‐terminal fragment (25 residues) is reported. Antisera were raised against the enzyme and purified by affinity chromatography. The antisera were monospecific and gave one precipitation line with purified as well as with crude phospholipase C, showing that no antigenic contaminants were present in the purified preparations used as antigen. The antibodies were purified to the extent that about two molecules neutralized one enzyme molecule. The enzyme is quite resistant to denaturation by urea, sodium dodecyl sulphate or heat (in the presence of 1 mM Zn2+). Phospholipase C hydrolyses phosphatidylcholine, phosphatidylethanolamine and phosphatidylserine. Under the conditions used phosphatidylglycerol, cardiolipin, phosphatidylinositol, sphingomyelin, lysophosphatidylcholine and lysophosphatidyl ethanolamine were not substrates. Replacement of Zn2+ by Co2+ or Ni2+ or variation of pH (7.2–8.3), did not change the range of substrates. Phosphatidylcholine was the best substrate among the isolated phospholipids and dicaproylphosphatidylcholine was clearly a better substrate than dipalmitoylphosphatidylcholine. Copyright © 1977, Wiley Blackwell. All rights reserved