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)

Adult female meadow voles maintained from birth in a long photoperiod (14 h light, 10 h darkness; LD 14:10) were ovariectomized or sham-ovariectomized and housed subsequently in long or short (LD 10:14) photoperiods for 10 wk. Absolute and relative daily food intake, body mass, carcass lipid and water content, and lipoprotein lipase activity of white adipose tissue were reduced in voles housed in short photoperiods. Ovariectomy resulted in increases in food intake and body weight and altered carcass composition in long-day voles, but these changes were negated in voles kept in short photoperiods. Responsiveness to short photoperiods promotes winter weight loss and subsequent energy intake savings and counteracts the body weight increases normally associated with gonadal quiescence and diminished hormone secretion.
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PMID:Short photoperiods counteract the effects of ovariectomy on energy balance of voles. 636 38

beta 2-Glycoprotein I (beta 2GI) has recently been identified as a component of circulating plasma lipoproteins. The metabolic role of this apolipoprotein is not known with certainty; it has been reported that beta 2GI has a high affinity for triglyceride-rich particles, causing their selective precipitation by detergents, and activates lipoprotein lipase in the in vitro hydrolysis of artificial lipid emulsions. In the present report, we have evaluated the secondary, tertiary, and quaternary structure of lipid-free beta 2GI. The weight average molecular weight of beta 2GI, as determined by sedimentation equilibrium measurements, was 43,000 in the presence and absence of denaturing agents. Thus, in contrast to other apolipoproteins, apolipoprotein H (apo-H) does not self-associate in aqueous solution. The circular dichroic spectra of apo-H is unusual in that there are no strong negative bands in the far-ultraviolet region of the spectrum; there is a weak positive maximum at 235 nm and a relatively weak negative maximum at 205 nm. Treatment with guanidinium chloride results in a loss of the positive band with only minor changes in the intensity of the band at 205 nm. Apolipoproteins A-I, A-II, C-I, and E, in contrast, have a secondary structure that contains a high percentage of residues in an alpha-helical configuration and undergo major changes in structure at low concentrations of guanidinium chloride. Highly flexible proteins, such as apolipoproteins A-I, A-II, and C-I, absorb rapidly and reversibly to air-water interfaces, whereas more rigid proteins, such as the classical globular proteins, interact with the interface more slowly and irreversibly. This difference is due to the loosely folded tertiary structure of apolipoproteins and the ease with which they can change structure to accommodate a given environment. The surface activity of beta 2GI at neutral pH resembles that of typical globular proteins. Treatment with acid or base, although causing only minor changes in the circular dichroic spectra, resulted in major increases in the rate of absorption to an air-water interface; under these conditions the rates of absorption were similar to that found for apolipoprotein A-I. These results are consistent with a more flexible structure for beta 2GI in acid or base that resembles other loosely folded apolipoproteins. beta 2GI associates with plasma lipoproteins and satisfies all of the criteria to be classified as an apolipoprotein. The secondary, tertiary, and quaternary structure of beta 2GI is, however, quite different from that of other well characterized apolipoproteins. This difference in structure would be expected to affect protein-lipid interactions; the relationship between apo-H and other apolipoproteins may be similar to that proposed for integral versus peripheral membrane proteins.
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PMID:beta 2-Glycoprotein I. Molecular properties of an unusual apolipoprotein, apolipoprotein H. 640 35

The effects of 2-aminoethanesulfonic acid (taurine) and its structural analogs, 3-aminopropanesulfonic acid (homotaurine) and 4-aminobutanesulfonic acid (ABSA), on lipid metabolism were investigated in rats with dietary hyperlipidemia. The serum cholesterol levels increased approximately five-fold in rats fed a diet containing 0.5% cholesterol and 1% cholic acid for 10 d. omega-Aminosulfonic acids dissolved in water were orally administered for 10 d concurrently with the 0.5% cholesterol diet. Taurine suppressed elevation in serum cholesterol levels by 46.9 and 63.9% at doses of 250 and 500 mg/kg, respectively. Serum triglycerides levels, however, were not significantly altered by taurine. Both homotaurine and ABSA, 500 mg/kg each, inhibited the elevation in serum cholesterol levels to an extent, namely, 32.0 and 22.3% lower than that of the controls, respectively. Treatment with homotaurine in doses of 250 and 500 mg/kg significantly increased serum triglycerides levels by 37.6 and 35.9%, respectively, and ABSA (500 mg/kg) also revealed a tendency to raise these levels. All the sulfonic acids (500n mg/kg each) reduced cholesterol levels in the liver similarly, while changes in triglycerides levels in the liver were insignificant. Both taurine and homotaurine (t00 mg/kg each) inhibited intestinal absorption of cholesterol. The inhibitory effect of homotaurine was as great as 31.5% and greater than that of taurine. No influence of taurine (500 mg/kg) was observed in lipoprotein lipase activity in the epididymal fat tissue, but the activity did appear to be inhibited by homotaurine (500 mg/kg).
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PMID:Effects of omega-aminosulfonic acids on lipid metabolism in dietary hyperlipidemic rats. 663 58

This study was conducted to know the possibility that pectin-induced alterations in lipid metabolism of animals might be partly ascribed to galacturonic acid produced by the degradation of ingested pectin in the digestive tract. After a 4-week meal feeding twice a day, fasted rats were fed glucose and fructose and 3 h later orally administered 213 mg of pectin (from apple) or galacturonic acid per kg of body weight, or fed water alone. Significant changes in serum and liver lipids were observed 30 min and 1 h after the administration of pectin and galacturonic acid but not 5 h after the administration. Pectin and galacturonic acid showed contradictory effects on serum lipids, adipose tissue lipoprotein lipase activity and triacylglycerol (TG) production and removal rates. However, the elevation of total lipid and TG levels in liver with the sugar feeding was significantly inhibited by the administration of either pectin or galacturonic acid. These results support our hypothesis that galacturonic acid produced by the degradation of ingested pectin in the digestive tract may be partly responsible for the pectin-induced changes in lipid metabolism. This was discussed in relation to another possible regulation of lipid metabolism by short-chain fatty acids which are produced by the intestinal fermentation of pectin and galacturonic acid.
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PMID:Suppression of hepatic lipogenesis by pectin and galacturonic acid orally-fed at the separate timing from digestion-absorption of nutrients in rat. 666 64

The fluorescent phospholipid 1-acyl-2-[6-[(7-nitro-2,1,3benzoxadiazol-4 -yl) amino]-caproyl] phosphatidylcholine (C6-NBD-PC) was used as a substrate for porcine pancreatic phospholipase A2 (PA2) and bovine milk lipoprotein lipase (LpL). Hydrolysis of C6-NBD-PC by either enzyme resulted in a greater than 50-fold fluorescence enhancement with no shift in the emission maximum at 540 nm; Ca++ was required for PA2 catalysis. Identification of the products of hydrolysis showed cleavage at the sn-1 and sn-2 positions for LpL and PA2, respectively. For PA2, but not for LpL, there was a marked enhancement of enzyme catalysis at lipid concentrations above the critical micellar concentration of the lipid. Furthermore, apolipoprotein C-II, the activator protein of LpL for long-chain fatty acyl substrates, did not enhance the rate of catalysis of the water-soluble fluorescent phospholipid for either enzyme.
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PMID:Hydrolysis of a fluorescent phospholipid substrate by phospholipase A2 and lipoprotein lipase. 670 13

An enzyme which catalyzes the following esterase reaction was isolated from mouse serum: 12-O-tetradecanoyl phorbol 13-acetate (TPA) + H2O----phorbol 13-acetate + tetradecanoic acid. The recovery was 0.18% of total serum protein and 820-fold purification was achieved. The enzyme is composed of a single polypeptide chain with sugar moiety; its molecular weight was estimated to be 77,000. Its sugar content is 15%, the isoelectric point was 4.3, and the alpha-helix content was 15.3% . The activity is stable between pH 5 and 9 under 40 degrees C; it is insensitive to 2-mercaptoethanol and is not dependent on divalent cations. The optimal pH is around 7.5. The apparent Km for TPA is 6.6 X 10(-7)M. The hydrolysis of [3H]TPA is inhibited by phorbol diesters and phorbol 12-myristate, but not by phorbol and phorbol 13-acetate. The activity is inhibited to some extent by phosphatidylcholine, cholesterol, and lanosterol, but not by free fatty acids, fatty acid esters of glycerol, cholesterol esters, or cholestanol. The enzyme hydrolyzes ester linkages, but not peptide linkages of synthetic substrates. Esterase inhibitors and serine-reactive reagents affect the activity. Although sera from rodents displayed strong activity, such activity was not detected in human serum. Unlike lipoprotein lipase, the serum enzyme activity was not enhanced by treatment of the animal with heparin. These characteristics and the amino acid composition do not agree with any of the reported characteristics of known serum enzymes with esterase activity.
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PMID:Isolation and characterization of a murine serum esterase which hydrolyzes a tumor promoter, 12-O-tetradecanoyl phorbol 13-acetate. 671 73

Adipocyte precursor cultures prepared from the epididymal fat pads of genetically obese (fa/fa) and lean (Fa/Fa) Zucker rats grow similarly in culture. Addition of enriched medium (EM) containing human serum, insulin, and glucose stimulated lipid filling of the adipocyte precursors in both cultures. However, [3H] H2O incorporation into total lipids, fatty acid synthetase and lipoprotein lipase activities, and cytosolic protein contents are all decreased in the fa/fa compared with the Fa/Fa cultures. Substitution of lean or obese rat serum for human serum in the enriched medium does not alter the decreased lipogenic capacity of the fa/fa adipocyte precursor cultures.
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PMID:Lipogenesis in primary cultures of adipoblasts derived from genetically obese Zucker rats. 686 57

Fatty acids, monoacylglycerol, cholesterol, and phospholipids are taken up from blood by many different tissues. These substances, which are strongly amphipathic at physiological pH, are poorly soluble in water and neutral lipids (tyriacylglycerol nd cholesteryl ester). They are transported in blood as components of lipoprotein particles or, in the case of fatty acids, s monomers bound to albumin. Fatty acids derived from the diet are carried as triacylglycerol in chylomicrons and very low density lipoprpoteins (VLDL). Phospholipids and cholesterol absorbed from intestines are also transported in chylomicrons and VLDL. We propose that transport of fatty acids and monoacylglycerol from chylomicrons Tand VLDL) across capillary endothelium in extrahepatic tissues requires 1) conversion of chylomicron triacylglycerol to amphipathic lipids (fatty acids and monoacylglycerol) by lipoprotein lipase at the capillary surface, 2) location and lateral movement of ipolytic products in a continuous interface composed of the chylomicron surface film and the external leaflet of plasma and intracellular membranes of endothelial and parenchymal cells, and 3) removal of lipolytic products from the interface in endoplasmic reticulum where they are reesterified to traicylglycerol and accumulate between leaflets of endoplasmic reticulum. We suggest that cholesterol and phospholipids from chylomicrons, and fatty acids from plasma albumin, also cross capillary endothelium by lateral movement in cell membranes.
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PMID:Transport of lipid across capillary endothelium. 699 54

The monomer molecular size of bovine lipoprotein lipase was evaluated by sedimentation equilibrium measurements and by gel permeation chromatography in 6 M guanidinium chloride. To establish molecular weight unequivocally we determined the partial specific volume (v) experimentally. This was done by analyzing equilibrium concentration profiles from analytical ultracentrifugation in 6 M guanidinium chloride using buffers made up in H2O and 2H2O. The combined results gave a v of 0.71 +/- 0.007 ml/g and a molecular weight of 41,700 +/- 1000 for monomeric bovine lipoprotein lipase. This value did not change upon mild tryptic digestion; the elution volume upon gel permeation chromatography in 6 M guanidinium chloride was also unaffected by treatment with trypsin. Sedimentation equilibrium measurements of the trypsin-treated material in the presence of reducing agents gave limiting molecular weights of 19,000 and 23,000, demonstrating that mild trypsin digestion cleaved lipoprotein lipase into two polypeptide chains of similar size held together by disulfide bonds. Mild trypsin digestion also resulted in a loss of secondary structure as determined by circular dichroic measurements. Discussion centers around the correlation between these effects of trypsin on the molecular properties of lipoprotein lipase and the previously reported effects on the kinetic properties of the enzyme.
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PMID:Molecular properties of lipoprotein lipase. Effects of limited trypsin digestion on molecular weight and secondary structure. 710 13

Bovine milk lipoprotein lipase (LpL) catalyzes the hydrolysis of the water-soluble esters p-nitrophenyl acetate (PNPA) and p-nitrophenyl butyrate (PNPB). The same protein and same active site are involved in hydrolysis of water-soluble p-nitrophenyl esters and emulsified trioleoylglycerol since (a) trioleoylglycerol hydrolysis and PNPB hydrolysis activities coelute from the heparin-Sepharose affinity column used to purify LpL and (b) LpL-catalyzed hydrolyses of trioleoylglycerol and PNPB are inhibited to equal extents by phenylmethanesulfonyl fluoride. The effect of apolipoprotein C-II (apoC-II) on the LpL-catalyzed hydrolysis of PNPA and PNPB has been determined. ApoC-II inhibits hydrolysis of both esters, with a maximum extent of inhibition of 70-90%. Inhibition of the LpL-catalyzed hydrolysis of PNPB is specific for apoC-II, since apolipoproteins A-I, C-I, and C-III-2 have little effect on this reaction, and is partial noncompetitive in form. KI values for apoC-II inhibition of the LpL-catalyzed hydrolysis of PNPA and PNPB are in the range 0.26-0.83 microM. The effect of apoC-II on the temperature dependences of LpL-catalyzed hydrolysis of both esters and on NaCl inhibition of LpL-catalyzed PNPB hydrolysis is consistent with a change in rate-determining step with LpL and apoC-II interact. These results indicate not only that there is an interaction between apoC-II and LpL in aqueous solution in the absence of a lipid interface but also that this interaction conformationally modulates the active site of the enzyme.
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PMID:Lipoprotein lipase catalyzed hydrolysis of water-soluble p-nitrophenyl esters. Inhibition by apolipoprotein C-II. 715 70


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