Pancreatic lipase family

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1lpa opm.png
Complex of human pancreatic lipase with colipase
Identifiers
Symbol Lipase
Pfam PF00151
InterPro IPR013818
PROSITE PDOC00110
SCOP 1lpa
SUPERFAMILY 1lpa
OPM protein 1lpa

Triglyceride lipases (EC 3.1.1.3) are a family of lipolytic enzymes that hydrolyse ester linkages of triglycerides.[1] Lipases are widely distributed in animals, plants and prokaryotes.

At least three tissue-specific isozymes exist in higher vertebrates, pancreatic, hepatic and gastric/lingual. These lipases are closely related to each other and to lipoprotein lipase (EC 3.1.1.34), which hydrolyses triglycerides of chylomicrons and very low density lipoproteins (VLDL).[2]

The most conserved region in all these proteins is centred on a serine residue which has been shown[3] to participate, with an histidine and an aspartic acid residue, in a charge relay system. Such a region is also present in lipases of prokaryotic origin and in lecithin-cholesterol acyltransferase (EC 2.3.1.43) (LCAT),[4] which catalyzes fatty acid transfer between phosphatidylcholine and cholesterol.

Human pancreatic lipase[edit]

Pancreatic lipase, also known as pancreatic triacylglycerol lipase, is an enzyme secreted from the pancreas. As the primary lipase enzyme that hydrolyzes (breaks down) dietary fat molecules in the human digestive system, it is one of the main digestive enzymes, converting triglyceride substrates found in ingested oils to monoglycerides and free fatty acids.

Triacylglycerol + 2 H2O 2-monoacylglycerol + 2 fatty acid anions

Bile salts secreted from the liver and stored in gallbladder are released into the duodenum, where they coat and emulsify large fat droplets into smaller droplets, thus increasing the overall surface area of the fat, which allows the lipase to break apart the fat more effectively. The resulting monomers (2 free fatty acids and one 2-monoacylglycerol) are then moved by way of peristalsis along the small intestine to be absorbed into the lymphatic system by a specialized vessel called a lacteal. This protein belongs to the pancreatic lipase family.

Unlike some pancreatic enzymes that are activated by proteolytic cleavage (e.g., trypsinogen), pancreatic lipase is secreted in its final form. However, it becomes efficient only in the presence of colipase in the duodenum.

In humans, pancreatic lipase is encoded by the PNLIP gene.[5][6]

Human proteins containing this domain[edit]

Diagnostic importance[edit]

Pancreatic lipase is secreted into the duodenum through the duct system of the pancreas. Its concentration in serum is normally very low. Under extreme disruption of pancreatic function, such as pancreatitis or pancreatic adenocarcinoma, the pancreas may begin to autolyse and release pancreatic enzymes including pancreatic lipase into serum. Thus, through measurement of serum concentration of pancreatic lipase, acute pancreatitis can be diagnosed.[7]

Inhibitors[edit]

One peptide selected by phage display was found to inhibit pancreatic lipase.[8]

See also[edit]

  • Orlistat (a pancreatic lipase inhibitor marketed as an anti-obesity medication)

References[edit]

  1. ^ Chapus C, Rovery M, Sarda L, Verger R (1988). "Minireview on pancreatic lipase and colipase". Biochimie. 70 (9): 1223–1234. doi:10.1016/0300-9084(88)90188-5. PMID 3147715. 
  2. ^ Persson B, Bengtsson-Olivecrona G, Enerback S, Olivecrona T, Jornvall H (1989). "Structural features of lipoprotein lipase. Lipase family relationships, binding interactions, non-equivalence of lipase cofactors, vitellogenin similarities and functional subdivision of lipoprotein lipase". Eur. J. Biochem. 179 (1): 39–45. doi:10.1111/j.1432-1033.1989.tb14518.x. PMID 2917565. 
  3. ^ Blow D (1990). "Enzymology. More of the catalytic triad". Nature. 343 (6260): 694–695. doi:10.1038/343694a0. PMID 2304545. 
  4. ^ McLean J, Fielding C, Drayna D, Dieplinger H, Baer B, Kohr W, Henzel W, Lawn R (1986). "Cloning and expression of human lecithin-cholesterol acyltransferase cDNA". Proc. Natl. Acad. Sci. U.S.A. 83 (8): 2335–2339. doi:10.1073/pnas.83.8.2335. PMC 323291Freely accessible. PMID 3458198. 
  5. ^ Davis RC, Diep A, Hunziker W, Klisak I, Mohandas T, Schotz MC, Sparkes RS, Lusis AJ (December 1991). "Assignment of human pancreatic lipase gene (PNLIP) to chromosome 10q24-q26". Genomics. 11 (4): 1164–6. doi:10.1016/0888-7543(91)90048-J. PMID 1783385. 
  6. ^ "Entrez Gene: pancreatic lipase". 
  7. ^ Koop H (September 1984). "Serum levels of pancreatic enzymes and their clinical significance". Clin Gastroenterol. 13 (3): 739–61. PMID 6207965. 
  8. ^ Lunder, M., Bratkovič, T., Kreft, S., Štrukelj, B. (2005). Peptide inhibitor of pancreatic lipase selected by phage display using different elution strategies. Journal of Lipid Research, 46:1512-1516 http://www.jlr.org/content/46/7/1512.long

Further reading[edit]

This article incorporates text from the public domain Pfam and InterPro IPR013818