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)

The cellular and enzyme-histochemical differentiation of subcutaneous adipose tissue was studied in lean and obese pig fetuses at several ages. Positive reactions for a variety of cytosolic and organellar enzyme markers indicate metabolic competence of fetal adipocytes despite their small size (12 to 15 microns). Reactions for several enzymes decreased with fetal age and may be associated with a qualitative change in activity of adipocyte organelles. Age-associated increases in two lipogenic enzymes were observed in obese adipocytes. Observations on developing cells around hair follicles in the younger fetuses indicated significant temporal lags between the appearance of detectable enzyme activities in adipocytes. Enzyme activities in order of appearance were: dehydrogenases (cytosolic and mitochondrial), lipoprotein lipase and esterase. Esterase activity and several other enzymes were never observed in lipid positive cells that were not spherical. A proportion of hair follicle associated adipocytes in 110-d-old lean fetuses were histochemically and morphologically similar to brown adipocytes in the young rat. There was no evidence for brown adipocyte like cells in obese fetuses. Finally, comparison of the enzyme-histochemical differentiation of lean and obese fetal adipocytes indicates that fetal adipocytes become sensitive to external stimuli between 70 and 90 d of gestation.
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PMID:Cellular and enzyme-histochemical aspects of adipose tissue development in obese (Ossabaw) and lean (crossbred) pig fetuses: an ontogeny study. 401 44

The development of adipocytes was studied in primary cultures of rat adipose tissue stromal-vascular cells on collagen-coated glass coverslips. The effects of cell density and serum source on lipoprotein lipase (LPL), esterase and lipid histochemistry were evaluated. With a mixture of fetal calf serum (FCS; 2%), horse serum (2%) and pig serum (PS; 10%), large and loosely arranged clusters of adipocytes developed with time through an increase in cell number and size. An inverse relationship was observed between cell size and the number of adipocytes in a cluster. Lower cell densities were associated with large cells and the densest areas contained smaller cells. Unilocular adipocytes were observed by d 13 after plating and were generally absent from the densest area of the coverslips. Histochemically detectable LPL activity was demonstrable before lipid deposition in adipocyte clusters. A comparison of FCS (10%) and PS (10%) as the only serum sources indicated higher level of adipocyte esterase activity and lipid deposition in PS cultures. Cultures of cells from weanling (21 to 28 d old) and old (18 mo) rats were similar, whereas cells from younger rats (2 to 4 d old) formed denser cultures that contained fewer adipocytes. These adipocytes were small (less than 30 micron) and morphologically homogeneous (all multilocular). When cells from the very young rats (2 to 4 d old) were plated at low densities, an inverse relationship between cell size and number of cells in a cluster was also observed.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Adipocyte development in primary rat cell cultures, effect of cell density and serum source. 401 45

Fetuses were decapitated in one uterine horn in each of 14 sows at 45 d of gestation. Control (C) and decapitated (D) fetuses were removed by Caesarean section from three sows at 65 d of gestation (total of 10 D and 10 C fetuses), two sows at 85 d (six D and six C fetuses) and nine sows at 110 d (nine C and nine D fetuses) of gestation (Exp. 1). In Exp. 2, four to six fetuses were removed from each of two Ossabaw (O) gilts and three crossbred (C, Landrace X Yorkshire) gilts at 70 d of gestation, from three C and O gilts at 90 d of gestation and from three C and two O gilts at 110 d of gestation. In Exp. 1, one semitendinosis muscle was removed for histochemistry, whereas the contralateral muscle was removed and weighed. A medial portion of biceps femoris muscle was removed and used for histochemistry in Exp. 2. In both experiments, transverse sections (cryostat) of muscle were stained for lipid, glycogen (PAS) and the following enzymes: acid ATPase, NADH-TR, NADPH-TR, malate dehydrogenase (NAD- and NADP-dependent reactions; MDH), succinate dehydrogenase (SDH), alpha-glycerol phosphate dehydrogenase (with and without NAD; alpha-GPDH), isocitrate dehydrogenase (NAD dependent; ICDH), esterase, lipoprotein lipase and lipase. In Exp. 1, body and muscle weights of the two groups were not significantly different (P greater than .05) at 65 d of gestation, whereas D fetuses were smaller and had lighter weight muscles (P less than .05) at 85 d of gestation.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Enzyme histochemical studies in an ontogeny study of muscle development in Ossabaw and decapitated fetuses: cellular reactions. 401 46

A monoglyceride lipase was partly purified from extracts of rat adipose tissue by ammonium sulfate fractionation, alcohol precipitation, and lyophilization, or by ammonium sulfate fractionation, sodium deoxycholate treatment, and a second ammonium sulfate fractionation. Partial purification and heat denaturation showed the lipase to be different from tributyrinase and from an enzyme(s) which hydrolyzes diglycerides and triglycerides. Although the best preparations hydrolyzed monobutyrin this activity decreased with purification, indicating that the enzyme acts on insoluble substrates and is therefore a lipase and not an esterase. Further-more, classification of the enzyme as a lipase is consistent also with its behavior with inhibitors, since low concentrations of esterase inhibitors, e.g., fluoride, sodium deoxycholate, and physostigmine did not inhibit lipolytic activity. Inhibition studies with EDTA, sodium pyrophosphate, protamine, and fluoride showed that the enzyme differs from clearing factor lipase. The enzyme catalyzed hydrolysis of monostearin in the pH range 6.3-9.0, with a maximum at 7.4-7.6.
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PMID:Partial purification of monoglyceride lipase from adipose tissue. 594 37

The characteristics of acid esterase from the patient with Wolman's disease, a rare familial lipidosis, were studied. Enzymatic analysis as well as mineral analysis were performed on the patient's liver, spleen, and adrenal glands. Acid esterase was low in the patient's leucocytes and other affected tissues. Further enzymatic study with subcellular fractions of the liver in both patient and control subject revealed that acid esterase was mostly localized in the membrane of lysosomes. The lysosomal esterase was unaffected by Ca2+, Mg2+, EDTA, E600 (microsomal esterase inhibitor), and it was less inhibited by NaCl than other fractions. Studies with those inhibitors showed that acid esterase has different properties compared to other lipases, such as lipoprotein lipase, adipose tissue lipase, and hepatic microsomal lipase. Studies with inhibitors also gave a negative view on a possible suppressive interaction of the high content of calcium in the target organs with acid esterase in Wolman's disease.
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PMID:Characteristics of acid esterase in Wolman's disease. 651 76

Human plasma apolipoproteins apo A-I, A-II, C-I, C-II and C-III (with the exception of apoE), porcine pancreatic colipase and procolipase hydrolyze 4-methylumbelliferyloleate. In all cases, liberation of 4-methylumbelliferone could be inhibited by phenylmethylsulfonyl-fluoride, thus suggesting the involvement of serine residues. To the best of our knowledge this is the first report on the esterase activities of these peptides. Synthetic fragments of the lipoprotein lipase activator, apoC-II, prepared according to the known sequence, also possessed this esterase-type of activity. Furthermore, the esterase-type of activities of the synthetic apoC-II fragments with different chain lengths bore a relatively good correlation to the reported abilities of these peptides to produce activation of lipoprotein lipase. We propose a model for the mechanism of activation of lipoprotein lipase by apolipoprotein C-II. ApoC-II would enhance the apparent catalytic rate constant of lipoprotein lipase by functioning as a specific acyl-enzyme hydrolase. A similar catalytic mechanism is suggested for other protein co-factors of hydrolytic enzymes.
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PMID:Esterase-type of activity possessed by human plasma apolipoprotein C-II and its synthetic fragments. 662 23

While lipoprotein lipase (LPL) acts in vivo as an immobilized enzyme, its kinetics are commonly studied with soluble LPL (S-LPL). Hence kinetic parameters of S-LPL and heparin-Sepharose-immobilized LPL (B-LPL) were compared. A modified purification procedure for bovine milk, LPL gave a 56% yield of S-LPL, purified 7250-fold, and a specific activity of 27,000 mumol fatty acid/mg LPL/h when assayed with triolein (TG) emulsions in the presence of serum. The purified LPL also showed low but detectable esterase activity with p-nitrophenylacetate and p-nitrophenylbutyrate as substrates. Apolipoprotein C-II (C-II) had no effect on the esterase activity of LPL. Dixon plots of experiments with S-LPL indicated that heparin is a competitive inhibitor against both C-II and TG, and that the binding of either C-II or heparin to the enzyme is a mutually exclusive event. Similarly, the binding of TG and heparin to the enzyme is mutually exclusive. From the Dixon plots, the dissociation constant Ki for the LPL:heparin binary complex was determined to be 5.0 X 10(-8) M. In contrast to the heparin inhibitory effect on LPL activity against triolein, heparin had no effect on the esterase activity of LPL against p-nitrophenylacetate or p-nitrophenylbutyrate. Comparative studies with B-LPL and S-LPL, using triolein as substrate and apolipoprotein C-II or serum as activator, indicated that S-LPL has a higher apparent Km and lower apparent Vmax than B-LPL. It is concluded that most of the LPL bound to heparin-Sepharose is probably inaccessible to substrate, hence a low Vmax. However, Km (C-II) and Km (TG) were higher for B-LPL due to the competitive inhibitory effect of heparin on LPL. Consistent with these kinetic analyses and with the use of human very low density lipoproteins (VLDL) as substrate, S-LPL, even in the presence of heparin, was found to have an apparent rate of lipolysis of VLDL approximately ninefold greater than B-LPL.
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PMID:The comparative kinetics of soluble and heparin-Sepharose-immobilized bovine lipoprotein lipase. 663 55

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

Adipose tissue development was studied histochemically and histologically in fetuses from lean and obese sows. At 110 days of gestation, fetuses were removed from Ossabaw (obese-feral) sows and from sows selected for high backfat (obese-domestic) and for low backfat (lean) thickness. Body weights were similar for lean (916 +/- 225 g) and obese (822 +/- 167 g) domestic fetuses, whereas obese feral fetuses were smaller (631 +/- 70 g). Histological and histochemical analysis was conducted on subcutaneous tissue from over the shoulder. Staining for lipid-containing fat cells indicated similar concentrations of fat cells throughout the depth of the subcutaneous tissue from obese (domestic and feral) and lean fetuses. Adipocytes from obese fetuses were slightly larger (domestic 23 +/- 0.22 microns, feral 21.8 +/- 0.26 microns) than cells from lean fetuses (20.7 +/- 0.42 microns). The percentage glycogen positive (PAS) adipocytes was low and similar from all three fetal strains. Less than 10% of adipocytes from lean and obese domestic fetuses were esterase-positive, whereas 42% of adipocytes from obese feral fetuses were esterase-positive. All adipocytes from obese fetuses (domestic and feral) were lipoprotein lipase (LPL)-positive whereas all cells from lean fetuses were negative for LPL activity. Therefore, cellular and metabolic differences exist in adipose tissue of lean and obese pigs during the prenatal period of growth and development.
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PMID:Adipose tissue cellularity and histochemistry in fetal swine as affected by genetic selection for high or low backfat. 684 80

After a 5 week period of feeding a cholesterol-rich diet to rabbits, hyperresponders with high plasma cholesterol levels and hyporesponders with low plasma cholesterol levels could be distinguished from normal responders. The response was found to be correlated with the esterase genotype at the Est-2 locus. The increase in total body cholesterol was higher in hyper-than in hyporesponders. In both groups most of the accumulated dietary cholesterol was found in plasma and liver. Adrenal weight and plasma corticosterone levels were more increased in hyper- than in hyporesponders. The cholesterol-rich diet resulted in an augmentation of liver lipase and lipoprotein lipase activities. These lipolytic activities were more increased in hyper- than in the hyporesponders.
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PMID:Genetic and physiological aspects of cholesterol accumulation in hyperresponding and hyporesponding rabbits. 726 98


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