Lipase activity

Janda, K.D., Benkovic, 5.J., Lerner, R.A. Catalytic antibodies with lipase activity and R or 5 substrate selectivity. Science 244 437-440, 1989. 

Within the small intestine, bile-acid binding interferes with micelle formation. Nauss et al. [268] reported that, in vitro, chitosan binds bile acid micelles in toto, with consequent reduced assimilation of all micelle components, i.e., bile acids, cholesterol, monoglycerides and fatty acids. Moreover, in vitro, chitosan inhibits pancreatic lipase activity [269]. Dissolved chitosan may further depress the activity of lipases by acting as an alternative substrate [270]. 

The wide substrate tolerance of lipases is demonstrated by the resolution of organometallic substrates [129-131]. The presence of tin, selenium, or tellurium in the structure of secondary alcohols does not inhibit the lipase activity and enantiopure organometallic alcohols were obtained by acylation in organic media (Figure 6.48). 

Both ph ospholipids and apo C-II are required as cofactors for hpoprotein lipase activity, while apo A-11... 

Figure 25-5. Metabolism of high-density lipoprotein (HDL) in reverse cholesteroi transport. (LCAT, lecithinxholesterol acyltransferase C, cholesterol CE, cholesteryl ester PL, phospholipid A-l, apolipoprotein A-l SR-Bl, scavenger receptor B1 ABC-1, ATP binding cassette transporter 1.) Prep-HDL, HDLj, HDL3—see Table 25-1. Surplus surface constituents from the action of lipoprotein lipase on chylomicrons and VLDL are another source of preP-HDL. Hepatic lipase activity is increased by androgens and decreased by estrogens, which may account for higher concentrations of plasma HDLj in women.

Numerous workers have found that measurements of serum lipase activity are useful in the diagnosis of pancreatitis (83, 84, 85). Despite this, serum lipase determinations are not usually performed in clinical laboratories, probably due to inherent problems associated with the conventional methods, based on an emulsified lipid substrate. The methods are also not very suitable for manual batch analysis nor for automation due to laborious post incubation procedures. 

Lippi et. al (87) and Dirstine (88) circumvented titration by converting the liberated fatty acids into copper salts, which after extraction in chloroform are reacted with diethyldithio-carbamate to form a colored complex which is measured photometrically. While the end point appears to be more sensitive than the pH end point determination, the advantages are outweighed by the additional steps of solvent extraction, centrifugation and incomplete extraction when low concentrations of copper salts are present. Other substrates used for the measurement of lipase activity have been tributyrin ( ), phenyl laurate (90), p-nit ro-pheny1-stearate and 3-naphthyl laurate (91). It has been shown that these substrates are hydrolyzed by esterases and thus lack specificity for lipase. Studies on patients with pancreatitis indicate olive oil emulsion is definitely superior to water soluble esters as substrates for measuring serum lipase activity. 

Recently Shihabi and Bishop (93) described a refinement in the preparation of a stable substrate and demonstrated the feasibility monitoring the reaction kinetically. This procedure has been evaluated by Lifton et. al. (9 ), who found that this method correlated well (r 0.914) with the copper soap-lipase method of Dirstine. They concluded that the method was rapid (less than 5 min. per sample), accurate, precise and linear over a clinically useful range. Its simplicity allows its application as an emergency procedure. Attempts to use this assay for urine lipase activity were unsuccessful. 

Yang, J. S. and Biggs, H. G. Rapid, reliable method for measuring serum lipase activity. Clin. Chem. (1971),... 

There are few, if any, specific inhibitors of lipase activity. Instead, reported inhibition of lipase by saponins (Han et al., 2002), polysaccharides and tannins (Longstaff and McNab, 1991) is probably due to the non-specific interactions these phytochemicals have with proteins. 

Total pectinase, cellulase and lipase activities secreted by colonies were detected on BSM plates containing respectively 1% of citrus pectin, 2% Walseth cellulose and 1% olive oil + rhodamine. After few days at 30°C, pectin plates were covered by 1% CTAB for Ihour, positive colonies became surrounded by a clear halo walseth plates are not stained the halo is visible directly on positive clones lipase activity is revealed under UV on oil-rhodamine plates. 

In 1958 Sarda and Desnuelle [79] discovered the lipase activation at the interfaces. They observed that porcine pancreatic lipase in aqueous solution was activated some 10-fold at hydrophobic interfaces which were created by poorly water-soluble substrates. An artificial interface created in the presence of organic solvent can also increase the activity of the lipase. This interfacial activation was hypothesized to be due to a dehydration of the ester substrate at the interface [80], or enzyme conformational change resulting from the adsorption of the lipase onto a hydrophobic interface [42,81,82]. 

Superko, H., Bortz, W., Williams, P., Albers, J. and Wood, P., Caffeinated and decaffeinated coffee effects on plasma lipoprotein cholestrol, apolipoprotiens and lipase activity A controlled, randomized trial. American Journal of Clinical Nutrition 54, 599-605, 1991. 

Pancreatic enzyme activity is very low in premature neonates. Lipase activity increases 20-fold in the first 9 months of life. Since concentration of bile salts is also... 

J5. Jaume, J. C., Mendel, C. M Frost, P. H., Greenspan, F. S and Laughton, C. W., Extremely low doses of heparin release lipase activity into plasma and can thereby cause artifactual elevations in serum free thyroxine concentration as measured by equilibrium dialysis. Thyroid 6, 79-84 (1996). 

Two possible pathways for the biosynthesis of 2-AG have been proposed (1) a phospholipase C (PLC) hydrolysis of membrane phospholipids followed by a second hydrolysis of the resulting 1,2-diacylglycerol by diacylglycerol lipase or (2) a phospholipase Ai (PLA,) activity that generates a lysophospholipid, which in turn is hydrolyzed to 2-AG by lysophospholipase C (Fig. 5) (Piomelli, 1998). Alternative pathways may also exist from either triacylglycerols by a neutral lipase activity or lysophosphatidic acid by a dephosphorylase. The fact that PLC and diacylglycerol lipase inhibitors inhibit 2-AG formation in cortical neurons supports the contention that 2-AG is, at least predominantly, biosynthesized by the PLC pathway (Stella, 1997). However, a mixed pathway may also be plausible. 

Elner, VM, 2002. Retinal pigment epithelial acid lipase activity and lipoprotein receptors Effects of dietary omega-3 fatty acids. Trans Am Ophthalmol Soc 100, 301-338. 

Chiesa G, Michelagnoli S, Cassinotti M, Gianfranceschi G, Werba JP, Paz-zucconi F, et al. Mechanisms of high-density lipoprotein reduction after probu-col treatment changes in plasma cholesterol esterification/transfer and lipase activities. Metabolism 1993 42 229-235. 

Nie L, Niu S, Vega GL, Clark LT, Tang A, Grundy SM, et al. Three polymorphisms associated with low hepatic lipase activity are common in African Americans. J Hpid Res 1998 39 1900-1903. 

Deeth H C, (1993), Lipase activity and its effect on milk quality, Australian Journal of Dairy Technology, 48, 96-98. 

One of the most promising applications of enzyme-immobilized mesoporous materials is as microscopic reactors. Galameau et al. investigated the effect of mesoporous silica structures and their surface natures on the activity of immobilized lipases [199]. Too hydrophilic (pure silica) or too hydrophobic (butyl-grafted silica) supports are not appropriate for the development of high activity for lipases. An adequate hydrophobic/hydrophilic balance of the support, such as a supported-micelle, provides the best route to enhance lipase activity. They also encapsulated the lipases in sponge mesoporous silicates, a new procedure based on the addition of a mixture of lecithin and amines to a sol-gel synthesis to provide pore-size control. 

AII listed products contain pancrelipase. Pancrelipase contains not less than 24 USP units of lipase activity, not less than 100 USP units of amylase activity, and not less than 100 USP units of protease activity per mg. 

Several studies have been conducted on calcium-fat interactions in human infants (64-70). Low synthesis of bile salts and low pancreatic lipase activity may be responsible for poorer fat utilization in infants than in adults (63,71). Fat from infant formulas may be lower than that from human milk because of the lack of a bile-stimulated lipase in the former (72). In infants, fat absorption tends to decrease with increase in fatty acid length, with lower degree of saturation, and with increase of total fat (3). Triglyceride structure may also influence fat absorption in the infant and, thus, indirectly, might also affect calcium absorption in the infant. 

J. Xu et al. [283] have shown that immobilization of enzymes can be done using a specially designed composite membrane with a porous hydrophobic layer and a hydrophilic ultrafiltration layer. A polytetrafluoroethylene (PTFE) membrane with micrometer pores as an excellent hydrophobic support for immobilization was employed for the porous hydrophobic layer, and a biocompatible material of polyvinyl alcohol (PVA) which provided a favourable environment to retain the lipase activity was used to prepare the hydrophilic... 

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