Abstract
In order to identify fish enzymes displaying novel biochemical properties, we have chosen the common stingray (Dasyatis pastinaca), one of the most primitive living jawed aquatic vertebrates as a starting biological material to purify a lipase. A stingray pancreatic lipase (SPL) was purified from delipidated pancreatic powder. The SPL molecular weight was around 55 kDa which is slightly higher than that of known classical pancreatic lipases (50 kDa). This increase in the molecular weight was due to glycosylation. Like classic pancreatic lipases, SPL was found to be much more active on short-chain triacylglycerols than on long-chain ones. Natural detergents act as inhibitors of the SPL activity. This inhibition can be reversed by the addition of stingray colipase. Starting from total pancreatic messenger RNAs (mRNAs), partial stingray pancreatic lipase complementary DNA (cDNA) was synthesized by reverse transcriptase-polymerase chain reaction (RT-PCR) and cloned into the PGEM-T vector. Partial amino acid sequence of the SPL was homologous to that of Japanese eel, porcine, and human pancreatic lipases. A 3D structure model of the sequenced part of SPL was built using the 3D structure of porcine pancreatic lipase as template, since both lipases shared an amino acid sequence identity of 60 %.