1hpl
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(New page: 200px<br /><applet load="1hpl" size="450" color="white" frame="true" align="right" spinBox="true" caption="1hpl, resolution 2.3Å" /> '''HORSE PANCREATIC LIPA...)
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Revision as of 14:36, 20 November 2007
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HORSE PANCREATIC LIPASE. THE CRYSTAL STRUCTURE AT 2.3 ANGSTROMS RESOLUTION
Overview
Pancreatic lipase (EC 3.1.1.3) plays a key role in dietary fat digestion, by converting triacylglycerols into 2-monoacylglycerols and free fatty, acids in the intestine. Although the crystallographic structures of the, human pancreatic lipase and of a human lipase-porcine colipase complex, have been solved, no refined structure of pancreatic lipase has yet been, published. The crystal structure of the horse enzyme was solved by the, molecular replacement method from the model of the human pancreatic lipase, and subsequently refined to 2.3 A resolution. The final model contains two, molecules of 449 amino acid residues each in the asymmetric unit, 705, well-defined water molecules and two calcium ions. The two molecules in, the asymmetric unit of the orthorhombic crystals are related by a 2-fold, non-crystallographic symmetry axis as in the case of the human lipase., However, the association between the two molecules in their respective, crystal forms is different. The overall molecular structure of the horse, lipase is very similar to that of the human enzyme. The horse lipase is, made up of two well-defined domains. The N-terminal domain which bears the, active centre has a typical alpha/beta hydrolase fold topology. The, C-terminal domain which is devoted to colipase binding has a beta-sheet, sandwich topology. Comparison of equivalent C alpha atom positions between, the final model of the horse lipase and the human lipase structure shows, only slight differences which are mainly located in the C-terminal domain., The horse enzyme possesses the common features of the known mammalian and, microbial lipases, in particular the "flap" covering the catalytic triad., In addition to more precise information concerning these features, the, elucidation of the horse lipase crystal structure allowed us to better, understand the structural basis of the kinetic behaviour of pancreatic, lipases towards a soluble substrate, p-nitrophenyl acetate, and the, different sensitivity of these enzymes towards limited proteolysis.
About this Structure
1HPL is a Single protein structure of sequence from Equus caballus with CA as ligand. Active as Triacylglycerol lipase, with EC number 3.1.1.3 Full crystallographic information is available from OCA.
Reference
Horse pancreatic lipase. The crystal structure refined at 2.3 A resolution., Bourne Y, Martinez C, Kerfelec B, Lombardo D, Chapus C, Cambillau C, J Mol Biol. 1994 May 20;238(5):709-32. PMID:8182745
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