Secretion of phospholipase B from Saccharomyces cerevisiae.

Phospholipase B and lysophospholipase activity is secreted from yeast cells (Saccharomyces cerevisiae) growing aerobically in batch cultures during the exponential phase. A glycoprotein with both activities running on SDS-polyacrylamide slab gels as a broad band between 200 000 and 280 000 Da was purified about 2500-fold by gel filtration, chromatofocusing and hydrophobic interaction chromatography with octyl-Sepharose. The secreted phospholipase has a slightly higher carbohydrate content of 41 mumol/mg protein compared to a form of the enzyme associated to the plasma membrane described in the previous communication (Witt, W., Schweingruber, M.E. and Mertsching, A. (1984) Biochim. Biophys. Acta 795, 108-116) and exerts very similar enzymatic properties. Fatty acids are set free from lysophosphatidylcholine with a 68-fold higher rate than from phosphatidylcholine with a concomitant generation of the corresponding diacyl compound. pH optima of 3.0 and 3.5 were determined with phosphatidylcholine and lysophosphatidylcholine, respectively. During the enzymatic degradation of the cell wall, high amounts of phospholipase activity were released, indicating that the enzyme is present in the periplasmatic space or associated to cell wall components.