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

---

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

A lower accessibility to water-soluble quenchers of tryptophanyls of VLDL apolipoproteins B, E, C as compared to LDL apoB chromophores has been detected by a fluorescence quenching technique. The dynamic behaviour of the tryptophanyls of VLDL amphipathic apolipoproteins E and C did not change in the presence of a detergent, Tween-20, at sub-lytic concentrations. However, a reversible structural transition registered by the 'red' shift of the emission spectrum maximum and the changes in the quenching pattern by I- occurred under these conditions. The increase in the VLDL tryptophanyl accessibility to acrylamide and the decrease in the quenching constant were observed at partial and complete solubilization of the VLDL particles by the detergent. Dissociation of apolipoproteins from VLDL occurred after their treatment with Tween-20 or lipoprotein lipase isolated from bovine milk, and the tryptophanyl population not participating in fluorescence energy transfer on lipid phase-localized fluorescent probe pyrene appeared. In the presence of Tween-20, the relative affinity of apoE for the lipid matrix of VLDL was lower than that of apoC. Besides, the uncompetitive mode of inhibition of the LPL activity by apoC-III has been demonstrated. It is suggested that: (1) the amphipathic apolipoproteins E and C are organized as clusters on the VLDL surface and/or partially shielded by apolipoprotein B: (2) self-regulation of lypolysis may exist involving detergent-like reaction product accumulation and changes in relative apolipoprotein contents.
...
PMID:Topo-dynamic characteristics of human plasma VLDL apolipoproteins and efficiency of triacylglycerol hydrolysis by lipoprotein lipase. 277 63

Lipoprotein lipase (LPL; triacylglycero-protein acylhydrolase, EC 3.1.1.34) was purified from bovine milk. Synthetic oligonucleotides were prepared, based on the amino acid sequences of three peptides obtained from partial digestion of purified LPL, and were used as probes to isolate cDNA clones for LPL mRNA from a bovine mammary gland. One of the clones, pLPL-49R2, contains an insert cDNA (49R2) of about 3.2 kilobases (kb) that hybridizes to all three probes and encodes a polypeptide that includes the NH2-terminal sequence of bovine LPL reported recently [Ben-Avram, C. M., Ben-Zeev, O., Lee, T. D., Hagga, K., Shively, J. E., Goers, J., Pedersen, M. E., Reeve, J. R. & Schotz, M. C. (1986) Proc. Natl. Acad. Sci. USA 83, 4185-4189]. Complete nucleotide sequence analysis revealed that cDNA insert 49R2 contains the entire coding region for LPL as well as a 3' untranslated region of about 1.6 kb. The predicted amino acid sequence indicates that bovine LPL is a hydrophilic protein consisting of 450 amino acids (Mr 50,548) in its unglycosylated form. Blot hybridization analysis of poly(A)+ mRNA from bovine mammary gland demonstrated that there are at least three sizes of LPL mRNAs--3.2, 2.5, and 1.7 kb--with the 2.5-kb mRNA being the most abundant. Restriction endonuclease mapping of other cDNA clones suggested that the variation in mRNA size results from differential utilization of polyadenylylation signals during mRNA processing.
...
PMID:Molecular cloning and sequence of a cDNA coding for bovine lipoprotein lipase. 288 34

Effects on plasma lipoproteins, lecithin:cholesterol acyltransferase (LCAT), and postheparin lipase (LPL and HTGL) activities were studied in 18 patients with familial hypercholesterolemia during 8-week treatment periods with colestipol (15 g/d), fenofibrate (0.25 g/d), and colestipol plus fenofibrate. Lipoprotein lipids and apolipoproteins were determined by standard procedures, LCAT by a self-substrate method, and lipases by nonradioisotopic methods. Colestipol and fenofibrate, each given independently, caused similar percentage decreases in LDL cholesterol and apolipoprotein B: -18.4% and -8.6% v -17.4% and -10.6% Colestipol increased the VLDL cholesterol concentration, whereas fenofibrate reduced this parameter but increased HDL cholesterol and apolipoprotein A-I levels. The combination of both drugs led to a substantial fall in LDL cholesterol (-36.8%) and in apolipoprotein B (-28.3%) and maintained the other effects of fenofibrate on VLDL and HDL. Colestipol, given independently or with fenofibrate, produced an increase of the fractional esterification rate of the LCAT enzyme (+25.3% and +36.2%). Fenofibrate stimulated the postheparin LPL enzyme by +16.1% and +21.7%, respectively. This study indicates the complementarity in effectiveness when both drugs were administered together. The appropriate reduction in LDL was combined with the favorable effects on HDL in familial hypercholesterolemia.
...
PMID:Low-dose colestipol plus fenofibrate: effects on plasma lipoproteins, lecithin:cholesterol acyltransferase, and postheparin lipases in familial hypercholesterolemia. 291 46

Conditioned serum-free medium of Ob17 cells transformed by the middle-T-only gene of polyoma virus (Ob17MT cells) is able to support growth and adipose conversion of the parental Ob17 cells. Conditioned media from 3T3-F442A cells (untransformed preadipocyte clonal line) and MTT4 cells (middle-T-transformed non-preadipocyte clonal line) are inactive. The serum-free conditioned medium of Ob17MT cells is also active on growth and adipose conversion of 3T3-F442A cells. The morphological differentiation of Ob17 cells is accompanied by the expression of early (lipoprotein lipase, LPL) and late (glycerol-3-phosphate dehydrogenase, GPDH) biochemical markers of adipose conversion. Bio-Gel P-60 chromatography and SDS-PAGE have allowed characterization of a mitogenic fraction of apparent MW approximately equal to 28 Kd distinct from an adipogenic fraction of apparent MW less than 10 Kd. This adipogenic fraction is only required for the acquisition of the GPDH activity and is therefore active on terminal differentiation.
...
PMID:Transformation of Ob17 cells promotes proliferation and differentiation of Ob17 preadipocytes via distinct extracellular intermediates. 301 89

The spontaneous secretion of lipoprotein lipase has been examined in adipose cells of mouse Ob17, Ob17SA and 3T3-F442A clonal lines as well as in rat adipose cells in primary culture. Striking differences are observed both in serum-free and serum-supplemented media, rat adipose cells and 3T3-F442A cells being the most active. Insulin from 10(-11) M to 10(-9) M was able to modulate the rate of LPL secretion from 2- to 4-fold. The stimulatory effect of insulin on this process occurred within 30 min in cells treated or not with cycloheximide. It is concluded that insulin is able to modulate the rate of LPL secretion independently of the synthesis of new enzyme molecules on a short-term basis and within a physiological range of concentrations.
...
PMID:Short-term stimulation by insulin of lipoprotein lipase secretion in adipose cells. 304 72

The effects of sepsis on lipid metabolism may be summarized as follows: The increased plasma catecholamine concentration stimulates adipose tissue FFA release. The increased FFA mobilization and plasma concentration results in an enhanced FFA uptake by the liver which promotes TGFA synthesis and output. Thus, triglyceride appearance rate also can be increased during hypermetabolic sepsis. In severe sepsis, the regulatory signals to increase FFA release from adipose tissue may be counterbalanced by blood flow limitations that inhibit FFA release, possibly due to the inadequate availability of the plasma carrier, albumin. Under such conditions, the arterial FFA concentration may be unchanged or decreased along with similar changes in the rate of peripheral FFA utilization. Triglyceride metabolism can also be altered during septic conditions in which plasma levels of cytokines are very high. Cytokines, notably TNF and IL-1, suppress synthesis of lipoprotein lipase which decreases the rate of TGFA clearance. Thus, hypertriglyceridemia can develop in the absence of elevated plasma FFA levels. The plasma concentration of cytokines necessary to inhibit LPL and how often this form of hypertriglyceridemia occurs in human sepsis are unknown at present. The sequence of events describing the influence of sepsis on carbohydrate metabolism is postulated to be the following: The presence of bacteria, or their products (eg, endotoxin) either directly or indirectly (via stimulating mononuclear phagocytes to release cytokines) activate the immune tissues. Glucose utilization by these tissues, which are predominantly glycolytic, is thereby stimulated resulting in increased lactate production. At the same time, glucose uptake by skeletal muscle and lactate release are also elevated.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Alterations in lipid and carbohydrate metabolism in sepsis. 306 39

Plasma lipids, apoprotein A-I and B in serum and in lipoprotein fractions (VLDL + LDL, HDL2, and HDL3) obtained by preparative ultracentrifugation, as well as postheparin lipoprotein lipase activity (H-TGL and LPL) were evaluated in 17 subjects with primary biliary cirrhosis (stage II and III) subdivided into two groups according to the presence or absence of lipoprotein X (Lp-X). A reduction in total lipoprotein lipase activity was observed in both patient groups, compared to controls (P less than 0.01); the hepatic lipoprotein lipase was significantly reduced (P less than 0.01) only in the Lp-X-positive group. The lipid (477.8 +/- 154.3 vs 239.6 +/- 51.1; P less than 0.01) and protein (147.4 +/- 37.1 vs 83.3 +/- 19.7; P less than 0.01) masses in the VLDL + LDL fraction of the Lp-X-positive group were increased compared to controls. In the same group, the HDL2 fraction also showed an increase in lipid (186.6 +/- 80.0 vs 77.9 +/- 21.6; P less than 0.01) and protein (133.9 +/- 60.0 vs 67.9 +/- 16.5; P less than 0.01) masses; in addition, the HDL2 percent lipid composition was different in the two patient groups, showing a decrease in esterified cholesterol (20.4 +/- 3.6 vs 25.7 +/- 2.2; P less than 0.01) and an increase in phospholipids (59.2 +/- 2.9 vs 54.8 +/- 2.6; p less than 0.01) in the Lp-X-positive group.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Lipoprotein pattern and plasma lipoprotein lipase activities in patients with primary biliary cirrhosis. Relationship with increase of HDL2 fraction in Lp-X-positive and Lp-X-negative subjects. 316 90

1. Adipose tissue lipoprotein lipase (EC 3.1.1.34; AT-LPL), a rate-limiting enzyme in triglyceride storage in adipose tissue, is hormonally regulated and may be important in the maintenance of obesity. 2. In twelve obese women, AT-LPL activity was measured before weight loss, during weight loss and after 1 and 2 weeks of weight maintenance on either a high-carbohydrate or a high-protein diet. 3. When related to tissue weight, AT-LPL activity during the 2 weeks of weight maintenance was higher than the initial AT-LPL activity; there was no difference when activity was expressed per cell. 4. Changes in AT-LPL activity were not affected by diet composition. AT-LPL activity correlated with insulin levels and a change in insulin sensitivity of AT-LPL was observed after weight loss.
...
PMID:Diet composition and lipoprotein lipase (EC 3.1.1.34) activity in human obesity. 330 15

Functional lipoprotein lipase activity was recently described in rat brain. The present study was performed to further characterize the biologic significance of brain lipoprotein lipase (heparin releasable component) and elucidate regulatory factors. Comparative studies were performed on tissue (brain, adipose, and heart) heparin releasable lipoprotein lipase in the fasted and diabetic (streptozotocin 100 mg/kg BW IP) rat. Both fasting (96 hours) and diabetes (ten days) significantly decreased brain (cortical) (P less than .05) and adipose (epididymal fat pad) (P less than .001) lipoprotein lipase activity. In contrast, heart muscle enzyme activity was significantly increased (P less than .001) in response to fasting and diabetes. Refeeding (Purina chow 96 hours) and insulin replacement (96 hours) reversed these changes in tissue lipoprotein lipase consequent to fasting and diabetes, respectively. There was a positive correlation between the changes in serum insulin concentration and adipose lipoprotein lipase, but there was no correlation between this parameter and brain or heart lipoprotein lipase. In addition, although T3 therapy normalized the low T3 state associated with both fasting and diabetes, it had no effect on the enzyme activity in the studied tissues. However, subsequent studies demonstrated that hypothyroidism (2 weeks post thyroidectomy) significantly decreased brain lipoprotein lipase activity (P less than .001) and increased both the adipose (P less than .025) and heart (P less than .025) enzyme activity. T3 replacement (0.8 micrograms/100 BW/d for 1 week) reversed the effects of hypothyroidism. However, the relationship between brain enzyme activity and serum T3 was nonlinear as hyperthyroidism tended to reduce brain LPL activity.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Brain lipoprotein lipase is responsive to nutritional and hormonal modulation. 330 44

Lipolytic activity was measured in human plasma without prior administration of intravenous heparin. Eluted from heparin-Sepharose in a barbital buffer containing 6 mg/ml heparin, plasma lipolytic activities in 20 subjects were distributed between hepatic triglyceride lipase (HTGL, mean +/- SE 60.6 +/- 4.6%) and extrahepatic lipoprotein lipase (LPL, 39.4 +/- 4.6%). Confirmation of the identities of HTGL and LPL was provided by inhibitory antisera. Preheparin LPL activity was absent in plasma from a patient with type I hyperlipoproteinemia. Both preheparin HTGL and LPL activities correlated with the respective activities measured in plasma obtained 15 min after intravenous injection of heparin (rs = + .774 and + .685, respectively; n = 12). Evidence for the metabolic regulation of preheparin lipases was provided by measurement of significant increases in LPL and HTGL activities after oral glucose ingestion. Overall, preheparin plasma HTGL and LPL activities may reflect ongoing lipoprotein lipolytic activity in tissue beds, and because these measurements do not require the administration of intravenous heparin, they should prove useful for additional studies of short-term regulation of the lipases.
...
PMID:Plasma lipolytic activity. Relationship to postheparin lipolytic activity and evidence for metabolic regulation. 336 Feb 17


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---