Partial characterization of the bile salt-dependent triacylglycerol lipase from the leopard shark pancreas

Abstract

Leopard shark triacylglycerol lipase has been characterized as a crude pancreatic preparation. The enzyme demonstrated an absolute requirement for trihydroxy bile salts for activity with natural bile salts of the shark giving a 4-fold greater stimulation of activity than pure sodium taurocholate. Bile salts also protected the enzyme from apparent inactivation by p-chloromercuribenzoate and trypsin treatment. The shark lipase demonstrated a temperature optimum of 36° C and was rapidly inactivated at 50° C even in the presence of bile salts. Divalent metal ions were required for activity with Ca 2+ providing the greatest stimulation. At 22° C, pH 8.5 and in the presence of natural bile salts, the apparent V was about 0.6 μmol fatty acid released/min per mg protein. The shark enzyme hydrolyzed over 90% of the fatty acids from trioleoylglycerol and methyl esters of pancreatic lipase-resistant fatty acids were hydrolyzed at the same rate as typical fatty acid methyl esters. Hydrolysis of triacylglycerol proceeded about ten-times faster than wax ester hydrolysis. The kinetic properties of the leopard shark enzyme were compared to other bile salt-dependent lipolytic enzymes. Pancreatic lipase activity was not dectected.