Lipoprotein lipase serum

Difference between Hormone-Sensitive Lipase and Lipoprotein Lipase Serum Albumin and the Transport of Fatty Acids... 

Sample Collection and Enzyme Stability. Serum samples are collected with chemically clean, sterile glassware. Blood is allowed to clot at room temperature, the clot is gently separated from the test tube with an applicator stick, and the blood is centrifuged for 10 minutes at 1,000 g. If the red cells are known to contain the enzymes whose activity is being measured, as in the case of LD, even slightly hemolyzed serums must be discarded. When acid phosphatase is to be measured, the serum should be placed immediately in ice and processed as soon as possible, or it should be acidified by the addition of a small amount of sodium citrate. Anticoagulants such as EDTA, fluoride and oxalate inhibit some serum enzymes. However, heparin activates serum lipoprotein lipase. 

Rare genetic absence of lipoprotein lipase results in excess triglyceride in the blood and its deposition in several tissues, including liver, skin, and pancreas. Orange-red eruptive xanthomas over the mucous membranes and skin may be seen. Abdominal pain and acute pancreatitis may occur. Fasting chylomicronemia produces a milky turbidity in the serum or plasma. 

Lipoprotein lipase, an enzyme responsible for the hydrolysis of the triglyceride moiety of lipoproteins, has been shown to be activated by serum high-density lipoproteins (B4, K5, S6, S14), by very low density... 

F3. Fielding, C. J., Lim, C. T., and Scanu, A. M., A protein component of serum high density lipoprotein with cofactor activity against purified lipoprotein lipase. Biochem. Biophys. Res. Commun. 39, 889-894 (1970). 

G2. Ganesan, D., Bradford, R. H., Alaupovic, P., and McConathy, W. J., Differential activation of lipoprotein lipase form human post-heparin plasma, milk and adipose tissue by polypeptides of human serum apolipoprotein C. FEBS (Fed. Eur. Biochem. Soc.), Lett. 15, 205-208 (1971). 

H3. Havel, R. J., Shore, V. G., Shore, B., and Bier, D. M., Role of specific glyco-peptides of human serum lipoproteins in the activation of lipoprotein lipase. Circ. Res. 27, 595-600 (1970). 

Other- Liver disease with impaired hemostasis severe renal disease. Hyperlipidemia Heparin may increase free fatty acid serum levels by induction of lipoprotein lipase. The catabolism of serum lipoproteins by this enzyme produces lipid fragments that are rapidly processed by the liver. Patients with dysbetalipoproteinemia (type III) are unable to catabolize the lipid fragments, resulting in hyperlipidemia. 

D. Lipoprotein lipase. Fenohbrate is a hypotriglyc-eridemic drug that lowers plasma triglycerides by increasing the activity of hpoprotein lipase, the enzyme responsible for disassembly of triglycerides in serum lipoproteins (VLDL, IDL and chylomicrons). 

Lipid metabolism effects. Grains, in the ration of rats at a dose of 68 g/animal daily for 3 months, were active vs rats fed tapioca. Total serum cholesterol and triglycerides were higher than animals fed tapioca. Glucose-6-phosphate levels were lower, and triglyceride lipase and lipoprotein lipase were increased over levels found in the tapioca group k Seed oil, in the ration of rats at a concentration of 10% of the diet, was active. Liver triglycerides were lower in rats fed rice brain oil than those fed peanut... 

Chylomicrons deliver tiiacylglycerols to tissues, where lipoprotein lipase releases free fatty acids for entry into cells. Triacylglycerols stored in adipose tissue are mobilized by a hormone-sensitive triacylglycerol lipase. The released fatty acids bind to serum albumin and are carried in the blood to the heart, skeletal muscle, and other tissues that use fatty acids for fuel. 

Egelrud, T. and Olivecrona, T. 1973. Purified bovine milk (lipoprotein) lipase Activity against lipid substrates in the absence of exogenous serum factors. Biochem. Bio-phys. Acta 306, 115-127. 

Super, D. M., Palmquist, D. L. and Schanbacher, F. L. 1976. Relative activation of milk lipoprotein lipase by serum of cows fed varying amounts of fat. J. Dairy Sci. 59, 1409-1413. 

Another apolipoprotein, Pa-glycoprotein-1, or apoH, is a glycoprotein of Mr 54,000 found in all major lipoprotein density fractions, especially VLDL where it forms about 4% of the protein mass. Serum concentration is about 15-30 mg/100 ml. Two-thirds to three-quarters is found in the d > 1.21 g/ml fraction after ultracentrifugation (P19, P20). ApoH is taken up readily by a triglyceride-phospholipid emulsion (Intralipid) (P20) and it activates lipoprotein lipase (Nl). Lipoprotein lipase activation by either apoH or apoC-II is inhibited by apoC-III (Nl). 

Type I lipoproteinemia is generally caused by the inability of the organism to clear chylomicrons. The problem may be defective ApoC-II or a defective lipoprotein lipase. Very often, chylomicron clearance may be affected by injection of heparin, which apparently releases hepatic lipase from the liver into the circulation. ApoE disorders may be associated with type III lipoproteinemia, in which clearance of IDL is impeded. Increases in circulatory LDL are usually caused by a decrease in tissue receptors specific for ApoB-100. An extreme case of type Ha hyperlipoproteinemia is familial hypercholesterolemia, in which serum cholesterol levels may be as high as 1000 mg/dL and the subjects may die in adolescence from cardiovascular disease. There is total absence of ApoB-100 receptors. Mild type Ila and lib lipoproteinemias are the most commonly occurring primary lipoproteinemias in the general population. 

The enzymes responsible for the detrimental effects of lipolysis are of two main types those indigenous to milk, and those of microbial origin. The major indigenous milk enzyme is lipoprotein lipase. It is active on the fat in natural milk fat globules only after their disruption by physical treatments or if certain blood serum lipoproteins are present. The major microbial lipases are produced by psychrotrophic bacteria. Many of these enzymes are heat stable and are particularly significant in stored products. 

Early research on lipolytic enzymes in cows milk suggested that at least two major lipases were present a plasma lipase in the skim portion and a membrane lipase associated with the milk fat globule membrane (Tarassuk and Frankel, 1957) while later research indicated that there might be up to six different molecular species with lipase activity (Downey and Andrews, 1969). However, work by Korn (1962) showed that milk contained a lipoprotein lipase (EC 3.1.1.34) (LPL) with properties very similar to those of post-heparin plasma, adipose tissue and heart LPLs, particularly the enhancement of its activity on emulsified triglycerides by blood serum lipoproteins. It is now accepted that LPL is the major, if not the only, lipase in cows milk. Its properties have been reviewed by Olivecrona et al. (2003). 

Unlike milk LPL, microbial lipases do not require a fatty acid acceptor such as BSA (Bengtsson and Olivecrona, 1980). Blood serum has been found to activate some of these enzymes (Fitz-Gerald and Deeth, 1983), including P. fluorescens lipases, and these have, consequently, been designated lipoprotein lipases (Aisaka and Tarada, 1979 Stepaniak and Sorhaug, 1989). 

Anderson, M. 1982a. Factors affecting the distribution of lipoprotein lipase activity between serum and casein micelles in bovine milk. J. Dairy Res. 49, 51-59. 

The milk lipase that is activated by foaming and causes the rancidity of milk is a glycoprotein or a family of glycoproteins. It is inhibited by DFP and is specific for primary ester bonds (14), The physiological function of the lipase is mysterious since new-born animals already possess their own digestive lipases. Milk also contains a lipoprotein lipase which has the properties typical for such an enzyme it is sensitive to heparin and activated by serum proteins. This enzyme is probably serum lipoprotein lipase that has leaked into the milk (14). 

Insulin, among other things, also stimulates production of lipoprotein lipase (LPL). With insulin deficiency in diabetes, there is insufficient LPL to release fatty acids from the triglycerides of VLDL and chylomicrons (see Fig. 6.4), another reason for accumulating serum triglycerides, apart from increased VLDL production by the liver. 

A. Familial lipoprotein lipase deficiency (Type I lipoprotein pattern on electrophoresis). Serum triglycerides become elevated with particular elevation of chylomicrons. Tliere are xanthomas, rather than atherosclerosis. Pancreatitis may result from the action of pancreatic lipase on these elevated chylomicrons, with resultant excess triglyceride breakdown in the pancreas, pancreatic injury, and release of more pancreatic lipase. (Note that the body contains different kinds of lipases. There is a pancreatic lipase, which is a digestive enzyme a lipoprotein lipase, which is an extracellular enzyme that breaks down plasma triglycerides, thereby enabling fatty acids to enter cells and an intracellular lipase that breaks down stored triglycerides). 

Figure 2. A negative correlation between lipoprotein lipase activity in epididymal fat tissue and triglyceride concentration in blood serum of conrtol male guinea pigs (0.5% i.-ascorbic acid in diet) and in guinea pigs with a marginal vitamin C deficiency (0.5 mg of i.-ascorbic acidjanimaljd). Equation of the...

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