(full paper is archived in the Miller Library)
Title: Phospholipase activity in venom of the predatory marine snail Conus californicus
Student Author(s): Thompson, Luke R.
Faculty Advisor(s): Gilly, william
Location: Final Papers Biology 176H
Date: June 2001
Abstract: Phospholipase activity is known to be present in the venoms of many venomous animals, including snakes, bees, and one Conus species. Whole duct venom was extracted from several specimens of Conus californicus, dissolved in seawater, and centrifuged. The supernatant fraction was observed to possess robust cytolytic activity. The biochemical basis of this activity was explored using two enzymatic assays. First, proteolytic activity of the venom supernatant towards casein, a universal protease substrate, was assayed spectrophotometrically. Following incubation with the venom supernatant, unreacted casein was precipitated and activity assayed by measuring any increase in absorbance of the reaction mixture as a result of digested casein in solution. The venom showed no detectable caseinase activity. Second, phospholipase activity of the venom supernatant toward L,a-phosphatidyl choline was assayed. Activity was measured spectrophotometrically, based on an absorbance change of the pH indicator phenol red due to the liberation of free fatty acids. Significant phospholipase activity was detected. This activity increased with the addition of calcium, suggesting that the responsible enzyme is calcium-dependent. Activity was lost subsequent to heating, suggesting that the responsible enzyme was denatured.