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)

Free fat cells and stromal-vascular cells were prepared from rat adipose tissue by incubation with collagenase. NH(4)OH-NH(4)Cl extracts of acetone-ether powders prepared from fat cells contained lipoprotein lipase activity but extracts of stromal-vascular cells did not. Intact fat cells released lipoprotein lipase activity into incubation medium, but intact stromal-vascular cells did not. The lipoprotein lipase activity of the medium was increased when fat cells were incubated with heparin, and this was accompanied by a corresponding decrease in the activity of subsequently prepared fat cell extracts. Heparin did not release lipoprotein lipase activity from stromal-vascular cells. The lipoprotein lipase activity of NH(4)OH-NH(4)Cl extracts of fat cell acetone powders is increased by the presence of heparin during the assay. This increase is not due to preservation of enzyme activity, but to increased binding of lipoprotein lipase to chylomicrons. Protamine sulfate and sodium chloride have little effect on the binding of lipoprotein lipase to chylomicrons, but they inhibit enzyme activity after binding to substrate has occurred. These inhibitors do, however, inhibit the stimulatory effect of heparin on enzyme-substrate binding.
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PMID:The mechanism of heparin stimulation of rat adipocyte lipoprotein lipase. 430 30

Lipoprotein lipase activity (LLA) was measured in the adipose tissue of six healthy subjects and five members of a family in whom the trait for familial exogenous hypertriglyceridemia was segregating. The lipase activity measured was characteristic of lipoprotein lipase: increased by feeding, dependent on the presence of serum, and inhibited by sodium chloride and protamine sulfate. When compared with lipase activity in healthy individuals, LLA was grossly deficient in two siblings with postabsorptive chylomicronemia and was intermediate in both parents and one sibling, who had normal postabsorptive triglycerides. These findings are compatible with autosomal recessive inheritance. The hormone-sensitive lipolytic enzyme responsible for mobilization of free fatty acids from adipose storage was normal in the hyperlipemic subjects. After a 104-g fat meal, the serum triglyceride increased more in subjects heterozygotic for LLA deficiency than in the healthy subjects, and there was a relatively greater increase in chylomicrons and very low density lipoproteins in the affected individuals. These observations demonstrate the physiologic importance of lipoprotein lipase in removal of these lipoprotein groups and further clarify the differences between endogenous and exogenous hypertriglyceridemia.
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PMID:Tissue lipoprotein lipase in normal individuals and in individuals with exogenous hypertriglyceridemia and the relationship of this enzyme to assimilation of fat. 601 61

Homogenates of mouse lungs were separated by differential centrifugation into two fractions containing lipoprotein lipase, namely, a soluble and a membrane-bound fraction. Lipoprotein lipase was specifically identified by its inhibition by both protamine sulfate (3 mg/ml) and sodium chloride (0.9 mol/l). The enzymatic activity of each fraction was enhanced when serum was preincubated with the enzyme. Both enzyme fractions showed optimum activity at alkaline pH, but the membrane-bound enzyme showed a higher pH optimum. In addition, the apparent Km of the soluble enzyme was lower than that of the membrane-bound enzyme. It is concluded that there are two different forms of lipoprotein lipase in mouse lung tissue that differ in a number of aspects.
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PMID:Soluble and membrane-bound forms of lipoprotein lipase in mouse lung tissue. 687 41

Human peripheral blood monocytes and rabbit alveolar macrophages secreted lipoprotein lipase during culture. Within hours after plating, lipoprotein lipase had accumulated in the culture medium of monocytes, and the rate of accumulation increased with time in culture. The initial rate of secretion of lipoprotein lipase by alveolar macrophages was higher than in monocytes but decreased after 8--10 hr to values similar to those expressed by monocytes cultured for the same length of time. The enzyme was characterized as lipoprotein lipase (triacylglycero-protein acylhydrolase, EC 3.1.1.34) on the basis of pH optimum (7.8--8.2 for monocytes, 8.1 for alveolar macrophages), dependence on apolipoprotein C-II for activity, inhibition by 0.3--0.5 M sodium chloride and protamine sulfate, and retention of a heparin-Sepharose gel. The expression of lipoprotein lipase secretion by human monocytes may have important implications with respect to the development of foam cells in the arterial wall during atherogenesis.
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PMID:Lipoprotein lipase secretion by human monocytes and rabbit alveolar macrophages in culture. 695 Dec 2

Triglyceridase activity in porcine aorta extracts was determined by splitting of glycerol-tri-[1-14C]-oleate. On the basis of inhibition of the activity by sodium chloride and protamine sulfate, as well as on the basis of activation by apoproteins of high density lipoproteins, the occurrence of lipoprotein lipase in the aorta was demonstrated. The data obtained suggest that 60--80% of triglyceridase activity is due to lipoprotein lipase.
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PMID:[Types of triglyceridase in the pig aorta]. 731 30

Sensitive, reliable procedures are reported for the selective assay of lipoprotein lipase (LPL) and hepatic lipase (HL) in postheparin plasma samples. LPL is inhibited in the HL assay by inclusion of 0.76 mol/L sodium chloride in the substrate. In the LPL assay, specificity is attained by pretreating the sample with sodium dodecyl sulfate, which selectively denatures HL. This LPL method was validated by direct comparison with a procedure in which HL is inactivated by an antiserum to human HL. We used the described assays to quantify LPL and HL activity in 32 normal adults, demonstrating a clear sex difference for both enzymes. On average, the men displayed higher HL and lower LPL activities than did the women.
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PMID:Hepatic and lipoprotein lipases selectively assayed in postheparin plasma. 843 9

Studies in humans have indicated that dietary salt restriction raises plasma levels of total cholesterol (TC) and triacylglycerols (TAG). In order to explain the mechanisms involved, a rat experimental model was developed consisting of chronic feeding ad libitum isocaloric diets with variable sodium chloride contents. Rates of synthesis of plasma TAG were measured either as the increase of plasma TAG after blocking its removal from plasma by the intra-arterial pulse infusion of Triton-WR 1339, or as the plasma rate of incorporation of [(14)C]-oleic acid [(14)C]-TAG. Plasma TAG removal rate was determined by the intra-arterial pulse infusion of a lipid emulsion. Severe salt restriction increased the plasma concentrations of TAG (71%) and of TC (10%). This result was not due to modification of the rate of synthesis of plasma TAG but was attributed to a 55% slower rate of removal of the TAG-containing lipoproteins. An increased plasma non-esterified fatty acid concentration, probably due to a salt restriction-related insulin resistance, may have impaired the activity of the enzyme lipoprotein lipase.
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PMID:The rise of the plasma lipid concentration elicited by dietary sodium chloride restriction in Wistar rats is due to an impairment of the plasma triacylglycerol removal rate. 1150 Jan 77


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