The enzymic deacylation of p-nitrophenyl esters and phosphatidylcholine in vicia faba minor

Two enzymic deacylating activities have been detected in crude extracts of small fababeans—the hydrolysis of p-nitrophenyl fatty acyl esters and that of phosphatidylcholine. Kinetic studies demonstrated differences between the two activities with respect to substrate inhibition and to the effects of pH, Triton X-100, calcium chloride and mercuric chloride. The sequential activity of phospholipases A₁ and A₂, and lysophospholipase, in fababeans is postulated, and some similarity is indicated between the hydrolysis of p-nitrophenyl palmitate and fababean alkaline lipase. The significance of results from this study is discussed in relation to earlier work on lipid-degrading enzymes in fababeans.