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)

A method is described for the assay of lipoprotein lipase, using a stable, radioactive substrate emulsion. Fatty acid-labeled trioleoylglycerol was emulsified by homogenization in glycerol with lecithin as detergent. This anhydrous emulsion was stable for at least six weeks. Substrate solutions for enzyme assay were prepared by diluting the emulsion with buffer containing serum and albumin. The fatty acid produced on hydrolysis was isolated in a one-step liquid-liquid partition system. Incubations with extracts of acetone powders from adipose tissue displayed characteristics of lipoprotein lipase activity, i.e., serum dependence and inhibition by NaCl and protamine. The method is rapid (less than 1 hour), sensitive and reproducible, and suitable for routine use.
J Lipid Res 1976 Sep
PMID:A stable, radioactive substrate emulsion for assay of lipoprotein lipase. 0 64

Glycosaminoglycans (GG) were isolated from commercial Ateroid and compared with those from bovine duodenal mucosa and pancreas. The major GG in Ateroid is heparin. Heparan sulfate (HS) and dermatan sulfate were also found. HS, chondroitin sulfates, and heparin were isolated from duodenal mucosa after papain digestion, but a residue, non-digestible, was mostly heparin. Pancreas contains very little GG, and the GG composition is similar to that of mucosa. The heparin isolated from Ateroid and mucosa have similar lipoprotein lipase-releasing activity, but the former has considerably less anticoagulant activity. Interestingly, papain digestion of mucosa and pancreas did not release all heparin from the tissue, suggesting that the protein to which heparin is linked is not readily accessible to the enzyme.
Mol Cell Biochem 1975 Sep 30
PMID:Glycosaminoglycans from Ateroid and bovine duodenal mucosa and pancreas. 5 31

Two men aged 48 and 35 years with severe hypertriglyceridaemia, glucose intolerance, and a secondary anaemia had more apolipoprotein C-III-2 and less apo C-III-1 on their triglyceride-rich lipoproteins (d less than 1.006) than did types IV or V lipaemic controls. Although the patients' abnormal lipoproteins seemed to produce normal activation of lipoprotein lipase, they did not serve as an efficient substrate for purified lipoprotein lipase. Adipose tissue of case 1 had considerable lipoprotein-lipase activity and the hypertriglyceridaemia responded to dietary therapy (carbohydrate 180 g, fat 80 g, protein 60 g per day, and no alcohol). The haemolytic anaemia improved, but the patient remained glucose intolerant. The abnormal content of apo C-III-2 on the triglyceride-rich lipoproteins, rendering them resistant to clearance by lipoprotein lipase, is believed to have contributed to the patients' severe hypertriglyceridaemia.
Lancet 1979 Sep 29
PMID:Hypertriglyceridaemia associated with an abnormal triglyceride-rich lipoprotein carrying excess apolipoprotein C-III-2. 9 Jul 60

Incubation of 125I-labeled very low density lipoprotein (VLDL) with lipoprotein lipase-rich (postheparin) plasma obtained from intact or supradiaphragmatic rats resulted in the transfer of more than 80% of apoprotein C from VLDL to high density lipoprotein (HDL), whereas apoprotein B was associated with lipoprotein of density less than 1.019 g/ml (intermediate lipoprotein). The transfer of 125I-labeled apoprotein C from VLDL to HDL increased with time and decreased in proportion to the amount of VLDL in the incubation system. A relationship was established between the content of triglycerides and apoprotein C in VLDL, whereas the amount of apoprotein C in VLDL was independent of that of other apoproteins, especially apoprotein B. The injection of heparin to rats preinjected with 125I-labeled VLDL caused apoprotein interconversions similar to those observed in vitro. The intermediate lipoprotein was relatively rich in apoprotein B, apoprotein VS-2, cholesterol, and phospholipids and poor in triglycerides and apoprotein C. The mean diameter of intermediate lipoprotein was 269 A (compared with 427 A, the mean Sf rate was 30.5 (compared with 115), and the mean weight was 7.0 X 10(6) daltons (compared with 23.1 X 10(6)). From these data it was possible to calculate the mass of lipids and apoproteins in single lipoprotein particles. The content of apoprotein B in both particles was virtually identical, 0.7 X 10(6) daltons. The relative amount of all other constituents in intermediate lipoprotein was lower than in VLDL: triglycerides, 22%; free cholesterol, 37%; esterified cholesterol, 68%; phospholipids, 41%; apoprotein C, 7%, and VS-2 apoprotein, 60%. The data indicate that (a) one and only one intermediate lipoprotein is formed from each VLDL particle, and (b) during the formation of the intermediate lipoprotein all lipid and apoprotein components other than apoprotein B leave the density range of VLDL to a varying degree. Whether these same changes occur during the clearance of VLDL in vivo is yet to be established.
J Lipid Res 1975 Sep
PMID:Interaction of rat plasma very low density lipoprotein with lipoprotein lipase-rich (postheparin) plasma. 17 Mar 50

Metabolism of ruminant adipocytes involves the synthesis and mobilization of lipids. Rates of lipid synthesis from the uptake of preformed fatty acids (via lipoprotein lipase) and de novo synthesis of fatty acids are related to the energy balance. Acetate is the major carbon source for fatty acid synthesis with NADPH originating from the pentose cycle and the isocitrate cycle. Ruminant adipose tissue lacks the ability to utilize for lipogenesis those substrates that generate mitochondrial acetyl CoA because of an absence of ATP citrate-lyase and NADP-malate dehydrogenase. Lipid mobilization in ruminant adipocytes is apparently regulated via cAMP levels and a summary of the compounds investigated for lipolytic responses is presented. The control of lipid synthesis and mobilization is interrelated in ruminant adipose tissue. The coordinated manner in which these two functions are regulated is examined with regard to adipocyte responses to insulin and epinephrine. In both lipid synthesis and lipid mobilization, ruminant adipocytes are uniquely different from nonruminant adipose tissue. The physiological significance and possible basis for these species differences in adipose metabolism are discussed.
Fed Proc 1976 Sep
PMID:Intermediary metabolism of adipose tissue. 18 55

Anti-lipoprotein lipase sera injected intravenously in roosters blocked quantitatively the catabolism of very low density lipoprotein (VLDL) triglyceride. Antibodies were produced in rabbits immunized with highly purified lipoprotein lipase (LPL, glycerol ester hydrolase, E C 3.1.1.3) prepared from chicken adipose tissue. Following anti-LPL serum injection there was a linear increase in plasma triglyceride concentration. The rate of entry of triglyceride in plasma was estimated from the rate of triglyceride accumulation in the plasma of animals injected with anti-LPL serum, or from the disappearance curve of biologically labelled VLDL. In instances where both measurements were conducted in the same animals there was very close agreement between the two procedures. Inhibition of VLDL triglyceride catabolism of anti-LPL serum provided a way to characterize newly secreted VLDL that exhibited a broad spectrum of particle sizes with a median of 625 A degrees. They contained 76.2 +/- 1.2% triglyceride and had a high ratio of free to ester cholesterol (2.46 +/- 0.45). In control VLDL samples there was 46.1% triglyceride, and the ratio of free to ester cholesterol was 1.19. The complete inhibition of triglyceride removal by an antiserum prepared against adipose tissue LPL demonstrates that the NaCl-inhibited, serum-activated lipase prepared by affinity chromatography on heparin-Sepharose and concanavalin A-Sepharose columns is the enzyme responsible in vivo for the catabolism of VLDL triglyceride. Further, the kinetics of triglyceride accumulation in the plasma provide evidence that the site of degradation of VLDL triglyceride is within the plasma compartment.
J Lipid Res 1976 Sep
PMID:Effect of an anti-lipoprotein lipase serum on plasma triglyceride removal. 18 24

The hydrolysis of an emulsified triglyceride substrate by clearing factor lipase (lipoprotein lipase) normally requires the presence of particular activating polypeptide species. These are present in serum, together with other inhibitory species, as part of the serum lipoproteins. The paper describes a method whereby the net activating ability of individual human sera may be measured routinely. In a normal population, this activating ability is shown to be correlated positively with the fasting serum triglyceride concentration. As the fasting triglyceride concentration increases, there is a rise in the proportion of the total activating ability that is associated with the very low density lipoproteins. A dietary fat load does not raise the total activating ability but does increase the proportion of the total that is associated with the serum lipoproteins of lowest density.
Atherosclerosis 1976 Sep
PMID:Clearing factor lipase (lipoprotein lipase) activator. A method for the measurement of the net activating ability of human sera. 18 2

Primary monolayers of calf aortic endothelial cells were presented with isolated human very low density lipoproteins that had been labeled with radioactive triglyceride. The cells were observed to take up triglyceride over a 24 hr period; incorporation increased with exogenous lipoprotein concentrations, and up to 60% of the triglyceride taken up was converted to other cell lipids within 24 hr. When [2-3H]glyceryl tri[1-14C]oleate-labeled very low density lipoprotein was used, the 3H/14C ratio in the cell triglyceride was always similar to that of the exogenous lipoprotein triglyceride. Moreover, no significant hydrolysis of the exogenous very low density lipoprotein triglyceride was observed during the time of exposure to the cells. Similar experiments using doubly-labeled triglyceride exposed to endothelial cells in triglyceride-phospholipid liposome preparations also resulted in incorporation of the exogenous triglyceride without evidence of extracellular hydrolysis. The results indicate that primary monolayers of endothelial cells in culture are able to incorporate and metabolize very low density lipoprotein triglyceride. However, triglyceride does not appear to be significantly hydrolyzed during uptake, suggesting an absence of lipoprotein lipase activity in these cells.
J Lipid Res 1977 Sep
PMID:Uptake of very low density lipoprotein triglyceride by bovine aortic endothelial cells in culture. 19 2

Egg yolk lipoproteins of very low density were found to contain proteins with cofactor activity for lipoprotein lipase. When delipidated very low density lipoproteins were dissolved in 10 mM HCl and fractionated by gel filtration about two thirds of the protein were in several components with estimated molecular weights of 60000 to more than 170000. The major low-molecular-weight proteins were the dimeric and monomeric forms of a previously characterized 9000-dalton peptide. The cofactor activity was not associated with any of these major proteins. A large-scale fractionation method was developed by which two proteins fractions with cofactor activity for lipoprotein lipase were purified more than thousand-fold. One fraction had a molecular size of about 9000 daltons and the other had a size of about 5000 daltons. Both these fractions could be further separated on the basis of charge into several fractions with cofactor activity. The cofactor proteins were relatively soluble both at high and at low pH. The retained their cofactor activity after denaturation in guanidinium hydrochloride and after reduction. During the initial steps in the purification of the cofactor proteins another low-molecular-weight protein followed the cofactors. It had a single 17500-dalton peptide chain and was present in four variants, three of which contained carbohydrate.
Eur J Biochem 1977 Sep 15
PMID:Protein components of very low density lipoproteins from hen's egg yolk. 19 37

The removal rate of apoprotein-B (apo B) in very low density lipoprotein (VLDL) was decreased in individuals with broad beta disease when compared with endogenous hypertriglyceridemia. Following the injection of 125I-VLDL isolated from individuals with endogenous hypertriglyceridemia, both VLDL apo B fractional catabolic rate (0.058 +/- 0.029 hr-1) and VLDL apo-B turnover rate (0.300 +/- 0.070 mg/kg/hr) were lower in broad beta disease than in endogenous hypertriglyceridemia (fractional catabolic rate 0.112 +/- 0.046, p less than .05; turnover rate 0.640 +/- 0.199, p less than .005) despite equivalent plasma concentrations of VLDL-apo-B. Furthermore, conversion of VLDL apo-B to LDL was impaired in broad beta disease relative to endogenous hypertriglyceridemia. Differences in the kinetics of lipoprotein lipase-related triglyceride removal during a maximal heparin infusion were also demonstrated between these two disorders. These differences suggest an abnormality in the interaction of lipoprotein lipase with the lipoproteins of unusual composition in broad beta disease. This is further supported by the normalization of lipoprotein composition in broad beta disease by estrogen therapy, with a simultaneous change in the kinetics of lipoprotein lipase-related triglyceride removal towards those seen in endogenous hypertriglyceridemia.
Metabolism 1978 Sep
PMID:Impaired very low density lipoprotein and triglyceride removal in broad beta disease: comparison with endogenous hypertriglyceridemia. 21 Mar 51


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