Lipase, Human Pancreas

Pancreatic lipase (PL) is an organ-specific enzyme which is formed by the pancreas and is secreted into the pancreatic duct. In the small intestine it hydrolyzes the exogenous triglycerides. Pancreas lipase is activated by bile acid and colipase. Increased activity of pancreatic lipase in serum/plasma is indicative for a disease of the exocrine pancreas. The analysis of the pancreatic lipase acitivity in serum/plasma in the presence of upper abdominal symptons is helpful for differential diagnosis. In acute pancreatitis and/or recurrent attacks in chronic pancreatitis patients, the pancreatic lipase increases ~3-6 hours after onset of the pain and is used for monitoring the course of the disease. Human hepatic lipase (HL) is a member of a superfamily of lipases and phospholipases (EC 3.1.1.3) Human HL is synthesized primarily in the liver and is secreted into hepatic sinusoids where it becomes associated with surface of hepatocytes and endothelial cells. Deficiency in hepatic lipase in human subjects is associated with premature atherosclerosis and elevated concentrations of plasma triglyceride. It is thought that human hepatic lipase anchored on the liver cell surface may act as a ligand facilitating receptor-mediated endocytosis. But mechanisms whereby surface association of human hepatic lipase is achieved are not fully understood. The sequences within the carboxyl-terminal 73 amino acids are important for surface binding of human hepatic lipase. It has been hypothesized that four basic amino acids (K472, R473, K474 and R476) located at the carboxyl-terminal region play a critical role. It is thought that substituting the basic amino acid residues with alanine will impair HSPG binding of hepatic lipase and alter its function in facilitating remnant lipoprotein uptake via receptor-mediated endocytosis. Pancreatic lipase (PL), one of the exocrine enzymes of pancreatic juice, catalyzes the hydrolysis of emulsified esters of glycerol and long chain fatty acids. The substrate is not a single molecule but a nonaqueous phase of aggregated lipid (Brockerhoff and Jensen 1974). The operative substrate characteristic is aggregates of ester molecules, micelles or monomolecular film, interfacing an aqueous medium. Enzyme activity is directly related to the concentration of substrate molecules on the interface (Esposito et al. 1973; Lagocki et al. 1973). PL attacks the primary ester groups most readily. Monoglycerides are poor substrates (it is the 2-monoglycerides that are absorbed through the intestinal wall and reformed into lymph chylomicrons). Pancreatic lipases have been thoroughly reviewed by Brockerhoff and Jensen (1974), and Desnuelle (1972). Lieberman and Ollis (1975) have reported on lipase immobilized on stainless steel and polyacrylamide beads. Using a fluidized bed recycle reactor it is indicated that enzyme-substrate affinity is not altered.\n\nActivity: (same/more than) 1000u/mg\n\nUnit Definition: One unit is defined as the amount of enzyme that produces a change in absorbance at 340nm at 25 degrees C using triolein as substrate under colipase saturation, pH 9.2.\n\nStorage and Stability:\nMay be stored at 4 degrees C for short-term only. For long-term storage, aliquot and store at -20 degrees C. Aliquots are stable for at least 6 months at -20 degrees C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.

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SPECIFICATIONS

Catalog Number

L2496-10

Size

25ug

Form

Supplied as a liquid in 20mM Tris-HCl, pH 7.8

Purity

~ 95% by SDS-PAGE

References

1. University of Ottawa Heart Institute, Biomedical Research: Dr. Zemin Yao 1999-2001. 2. Methods of Enzymatic Analysis, Volume 4, Enzymes 2: Esterases, Glycosidases, Lyases, Ligases. Hans-Ulrich Bergmeyer (ed.) pp. 426, March 1984. 3. See protocol by Neumann, U. on p. 26 for the lipase assay.