Purification and properties of a phospholipid acyl hydrolase from plasma membranes of Saccharomyces cerevisiae.

The properties of a phospholipid acyl hydrolase bound to yeast plasma membranes are described in detail. The enzyme is capable of splitting all phospholipids which can be extracted from yeast cells. The specific activity with lysophosphatidylcholine as substrate was much higher than with phosphatidylcholine. With dipalmitoyl phosphatidylcholine as substrate a broad pH optimum was measured between pH 3.0 and 4.5. The membrane-bound enzyme was activated strongly by the anionic detergents SDS, deoxycholate and, to a lesser extent, by cholate. The uncharged detergent Triton X-100 and the zwitterionic detergent SB12 exerted an only slightly activating effect. KCl, NaCl, MgCl2, and CaCl2 were inhibitory in the presence of glycine/acetic acid buffer at pH 4.0. THe enzyme was solubilized by cholate or by SB12 in an active form from the plasma membrane and purified by acetone and (NH4)2SO4 precipitation or gel filtration with Sephadex G-200. THe phospholipid acyl hydrolase was identified as a glycoprotein with an apparent molecular weight of 145,000 by SDS slab gel electrophoresis.