The carboxyl ester lipase profile of the pyloric caecum from the crown-of-thorns starfish (Acanthaster planci)

Abstract

1. The lipase/esterase profile of the pyloric caecum of the crown-of-thorns starfish (Acanthaster planci) revealed on polyacrylamide gel electrphoresis four major bands of esterase activity. 2. Fractionation by ion-exchange chromatography identified two major populations of enzymes with respectively high p-nitrophenyl acetate or p-nitrophenyl palmitate hydrolytic activities. 3. Major bands of activity focused at isoelectric points of between 3.5 and 5.0. 4. Molecular weight estimates of non-denatured enzymes ranged from 110 to 460 kDa. 5. Esterasic activity was only partially inhibited by 0.2 × 10−3M PMSF but was completely inhibited by 10−5 M DFP. 6. A pH optimum of 7.0–7.6 was observed with p-nitrophenyl acetate and hydrolytic activity to this substrate was stable of 40°C for at least 30 min but was absent after incubation at 60°C for 30 min.