Structure of human pancreatic lipase

Abstract

Pancreatic lipase (triacylglycerol acyl hydrolase) fulfills a key function in dietary fat absorption by hydrolysing triglycerides into diglycerides and subsequently into monoglycerides and free fatty acids. We have determined the three-dimensional structure of the human enzyme, a single-chain glycoprotein of 449 amino acids, by X-ray crystallography and established its primary structure by sequencing complementary DNA clones. Enzymatic activity is lost after chemical modification of Ser 152 in the porcine enzyme, indicating that this residue is essential in catalysis, but other data are more consistent with a function in interfacial recognition. Our structural results are evidence that Ser 152 is the nucleophilic residue essential for catalysis. It is located in the larger N-terminal domain at the C-terminal edge of a doubly wound parallel beta-sheet and is part of an Asp-His-Ser triad, which is chemically analogous to, but structurally different from, that in the serine proteases. This putative hydrolytic site is covered by a surface loop and is therefore inaccessible to solvent. Interfacial activation, a characteristic property of lipolytic enzymes acting on water-insoluble substrates at water-lipid interfaces, probably involves a reorientation of this flap, not only in pancreatic lipases but also in the homologous hepatic and lipoprotein lipases.

Detergent compatible alkaline lipase produced by marine Bacillus smithii BTMS 11

“…Unlike most other bacterial lipases, the B. smithii lipase was observed to be a metallo-enzyme inhibited by EDTA as well as PMSF. These observations indicate that B. smithii lipase may possess a triad of three amino acids at its catalytic site just like many other lipases (Winkler et al 1990). A purified lipase from B. coagulans MTCC 6375 was also reported to be inhibited by EDTA, PMSF and total loss of activity in the presence of SDS (Nawani et al 1998;Yu et al 2007).…”

Identification of the active‐site serine in human pancreatic lipase by chemical modification with tetrahydrolipstatin

“…Sequence alignment based on the primary structure of the lipase reported by Winkler ¢t al. [10] shows that the pentapeptide can only correspond to VaI-148-SCr-152 of hPL, as this is the only sequence in the lipase which contains these five amino acids.…”

Covalent immobilization of porcine pancreatic lipase on carboxyl-activated magnetic nanoparticles: Characterization and application for enzymatic inhibition assays

“…Lipase obtained from pig's pancreas (porcine pancreatic lipase, PPL) is the most extensively used one due to its convenient accessibility, high stability, and broad specificity in transesterification reactions [3]. PPL is a small globular protein composed of a single chain of 449 amino acids with molecular weight of 50-52 kDa, and because it possesses 86% of homology with human pancreatic lipases, it has been usually used as a substitution for human pancreatic lipase in the enzyme inhibitor screening [4,5].…”