Catabolism of sulphoquinovosyl diacylglycerol by an enzyme preparation from Phaseolus multiflorus

An enzyme which will deacylate sulphoquinovosyl diacylglycerol (SQDG) has been partially purified from the leaves of runner bean (Phaseolus multiflorus). No monoacyl intermediate was observed and the acyl hydrolase was more active towards unsaturated molecular species of SQDG than towards saturated species. The major peak of activity of SQDG acyl hydrolase, separated on both DEAE-cellulose and Sephadex columns, also contained galactolipid acyl hydrolase activity. The distribution of these activities together with substrate competition and inhibitor experiments indicated that at least part of the SQDG acyl hydrolase activity was due to an enzyme that also hydrolysed galactolipids.