Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.1.34 (lipoprotein lipase)
7,025 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Analysis of plasma lipids of 30- and 185-day-old BIO 82.62 myopathic hamsters and age-matched normal controls revealed a decrease in only the concentration of cholesteryl esters of 185-day-old diseased animals. Measurement of lipoprotein lipase (LPL) activity in heart, muscle, and adipose tissue showed no difference between the activity of the enzyme in the heart and muscle of the cardiomyopathic hamsters and that of the age-matched controls. In adipose tissue, however, LPL activity was depressed in the diseased animals in both age groups. No difference was found in the activity of hormone sensitive lipase. Incorporation of sn[U-14C] glycerol-3-phosphate into total lipids was found to be depressed in homogenates of heart, muscle, and adipose tissue but unchanged in liver homogenates of diseased animals. It was concluded that the decrease in the capacity to synthesize glycerides, rather than limiting substrate concentrations, could be the cause of the decrease in the lipid content in some tissues of the cardiomyopathic hamster.
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PMID:Glyceride metabolism in the myopathic hamster. 89 3

The stereochemical course of in vivo hydrolysis of triacylglycerols by lipoprotein lipase was investigated by determining the structure of diacylglycerol intermediates in postheparin plasma of rats which had been fed [3H]glycerol-labeled Intralipid 2 h before an injection of heparin or had been given an injection of a mixture of [3H]glycerol-Intralipid and heparin. During the clearance of both the natural chylomicrons and the artificial emulsion, sn-2,3-diacylglycerols (60-80%) were found to be the dominant enantiomers. Similar results were obtained when the contribution of the hepatic lipase was altered, either by tying off the mesentery artery and portal vein before injection of heparin, or by injection of heparin directly into the portal vein. These findings are consistent with a preferential release of the acyl group from the sn-1 position of the triacylglycerol molecule as demonstrated previously in vitro. A preferential orientation of the substrate in the enzyme-substrate complex or at the oil-water interface is discussed as a possible basis for these effects.
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PMID:Preferential in vivo accumulation of sn-2,3-diacylglycerols in postheparin plasma of rats. 91 99

An antibody was prepared against purified rat heart lipoprotein lipase. 1. This antibody showed marked species specificity. It inhibited almost totally the lipoprotein lipase activity from all rat tissues examined (i.e., heart, adipose, postheparin plasma, and mammary gland), while having no effect on the activity of lipoprotein lipase partially purified from rabbit, guinea pig and bovine heart and from bovine milk. The antibody also had no effect on the hepatic lipase activity of rat postheparin plasma. 2. After antibody to rat heart lipoprotein lipase was recirculated for 5 min through isolated rat hearts, little or no lipoprotein lipase activity could be detected in the perfusate during 0-20 s of a subsequent non-recirculating perfusion with buffer containing 1 unit heparin/ml. 3. Following recirculation of antibody to lipoprotein lipase for 10 min and a non-recirculating perfusion with buffer for 2 min, the hearts no longer oxidized any significant amounts of 14C-labelled palmitate chylomicron triacylglycerol fatty acid to 14CO2 during a 15-min perfusion. The data give compelling evidence that the functional fraction of lipoprotein lipase in hearts is at the endothelial cell surface accessible to lipoprotein lipase antibody.
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PMID:Antibodies to lipoprotein lipase. Application to perfused heart. 92 25

The rate of inactivation of triglyceride hydrolase activity by protamine sulphate was determined in pooled, normal, post-heparin plasma. Two distinct first-order rates of inactivation were obtained and the derived constants used to calculate the lipoprotein lipase and hepatic lipase contributions to the total post-heparin triglyceride hydrolase activity in normal controls and in patients with familial hyperchylomicronaemia. The lipoprotein lipase was reduced in the patients whereas the hepatic lipase was normal. There was however a marked age-related increase in the hepatic enzyme activity in normal subjects. Post-heparin lipolytic activity, assayed in vitro against lipoproteins of d less than 1.006 derived from the patients, was markedly reduced in our hyperchylomicronaemic subjects. This assay correlated well with the lipoprotein lipase activity determined by selective protamine sulphate inactivation.
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PMID:Selective protamine sulphate inactivation of lipoprotein lipase and hepatic lipase in human post-heparin plasma: specific lipase levels in normals and in type I hyperlipoproteinaemia. 92 94

The nature of the lipolytic activity released from chicken livers perfused with Krebs-Ringer buffer (pH 7.0) containing heparin (50 or 10 U/ml), fraction V albumin (3%), and glycerol (20%) was investigated. The nonrecirculating perfusates contained both previously described NaCl-resistant "liver lipase" as well as an apoLp-Gluactivated lipoprotein lipase (LPL). Crude perfusate lipolytic activity was separated on heparin-Sepharose columns into two enzymatic peaks which were eluted at mean NaCl molarities of 0.75 M (liver lipase) and 1.2 M (LPL). The liver LPL activity was stimulated 7-fold by human apoLp-Glu (half maximal activity at 1.5 microgram/ml) and inhibited by apoLp-Ala, apoLp-Ser, apoLp-GlnI, and apoLP-GlnII. Liver LPL was fully inhibited by anti-adipose LPL immunoglobulins. The "liver lipase" was not affected by apoLp-Glu (3-34 microgram/ml) or anti-adipose LPL immunoglobulins. The data demonstrate the presence in liver perfusates of a LPL with properties similar to adipose tissue lipoprotein lipase.
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PMID:Identification of an adipose tissue-like lipoprotein lipase in perfusates of chicken liver. 92 21

The liver of the foetal guinea pig accumulates a large quantity of triacyglycerol late in gestation at the same time that adipose-tissue mass grows at its maximum rate and foetal adipose-tissue lipoprotein lipase activity and sensitivity to lipolytic hormones has substantially declined. The fatty acid for triacyglycerol synthesis is not synthesized in the foetal liver and it is unlikely that it originates from any of the foetal tissues. Before the accumulation of hepatic triacyglycerol the concentration of free fatty acids increases in both the umbilical vein and the maternal inferior vena cava. This occurs at a time when the triacyglycerol lipase activity in maternal adipose tissue is elevated and the rate of lipolysis, but not of fatty acid esterification, is higher than earlier in gestation or than in the non-pregnant state. It is proposed that the increase in lipolysis in maternal adipose tissue, brought about by an increase in circulating lipolytic hormones, mobilizes fatty acid, which passes to the foetus and is partly stored as hepatic triacylglycerol. The foetal liver effectively removes both long-and short-chain fatty acids from umbilical-vein blood. The rate of placental fatty acid transfer is more than adequate to account for the triacylglycerol accumulation.
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PMID:Lipid metabolism and mobilization in the guinea pig during pregnancy. 94 14

Chylomicrons isolated form rat intestinal lymph were incubated with plasma. Protein transfer to chylomicrons, reaction rate with purified lipoprotein lipase, and content of lipase cofactor were determined. While the overall protein content of chylomicrons was increased 3--4-fold, and the content of lipase cofactor increase 4-fold, reaction velocity of the activated particles with lipoprotein lipase was increased only 1.3-fold. Maximal rate of hydrolysis was achieved in the presence of much smaller quantities of activator than the lipoprotein particles were capable of binding, and chylomicrons were fully activated for triclyceride hydrolysis in the presence of only 10% plasma for triglyceride concentrations of up to 3 mg/ml. Cofactor protein was not rate-limiting for hydrolysis of triglyceride from chylomicrons. These results are discussed in the light of recent concepts of the regulation of lipoprotein lipase activity.
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PMID:Chylomicron protein content and the rate of lipoprotein lipase activity. 95 May 3

Human milk contains two lipases. One is a lipoprotein lipase with properties similar to the lipoprotein lipases that participate in the metabolism of blood plasma lipoproteins in several tissues. This enzyme is present in high activity in the lactating mammary gland where it facilitates the uptake of triglyceride fatty acids from the blood lipoproteins for production of milk lipids in the gland. The high activity of this enzyme in milk probably represent leakage of enzyme from the gland. This lipase is not stable at pH below 5 or in intestinal contents and it is unlikely that it participates in intestinal fat digestion. Its activity varies widely between individual milk samples, and there is a high correlation between its activity and the development of hydrolytic rancidity in the milk on storage. The other lipase is present in the milk in an inactive form which is activated by bile salts. This lipase is present in milk from primates but not in milk from lower animals. Human milk contains enough of this lipase to hydrolyze the milk lipids almost completely in less than half an hour at the pH and the bile acid and salt concentrations found in the small intestine of the human infant. It is probable that it increases the efficiency of milk fat absorption. The enzyme has a rather wide substrate specificity and may also act on other lipid substrates than triglycerides. In contrast to pancreatic lipase it hydrolyses all three ester bonds in a triglyceride. This may affect the physical chemistry of the lipids in the intestinal contents as well as their absorption and further metabolism in the musoca.
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PMID:Human milk lipases and their possible role in fat digestion. 98 May 24

Human post-heparin plasma contains at least two different triglyceride lipases (TGL). The plasma lipolytic activity has been attributed to extra-hepatic and hepatic origin. Both post-heparin triglyceride lipases were partially purified and characterized. With heparin-Sepharose 4 B affinity chromatography it was possible to partially purify human adipose tissue lipoprotein lipase (LPL) as well as a lipase from human liver. The effects of NaCl, pre-heparin plasma, pH and temperature on these two tissue lipases and plasma lipases were studied in parallel. Antibodies were produced against plasma hepatic triglyceride lipase (plasma H-TGL) that did not cross react with LPL. TGL activity of human liver was completely inhibited by antibodies against plasma H-TGL. From these results it appears that human post-heparin plasma contains two triglyceride lipase activities which originate from liver and extra-hepatic tissues such as adipose tissue.
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PMID:A comparative study of human tissue and post-heparin plasma triglyceride lipases. 100 6

The previously demonstrated inhibition of cow's milk lipoprotein lipase by apoLp-Ala and the deinhibition by monoglyceride have been studied in more detail. The apoLp-Ala inhibition is reversible by the addition of monoglyceride before or after enzyme additions. Quantities of monoglyceride accumulate during hydrolysis of triglyceride which are adequate to prevent inhibition by added apoLp-Ala. Accelerating reaction rates observed when the substrate contains the apoprotein at levels producing partial inhibition are also explained by monoglyceride production. These effects were observed with both crude preparations of skim milk and highly pruified lipase. It is suggested that the generation of monoglyceride may be important in facilitating hydrolysis of triglyceride in lipoproteins containing this inhibitory apolipoprotein.
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PMID:Effects of monoolein on hydrolysis of triglyceride by lipoprotein lipase in the presence of an inhibitory apolipoprotein. 103 36


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