Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0009443 (cold)
 92,137 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The purpose of this study was to determine whether, under physiological conditions, intracellular lipoprotein lipase [type L hormone-sensitive lipase (HSL)] activity varied inversely with triacylglycerol (TG) content of the heart. The results show that fasting from 7:30 A.M. to 7:30 P.M. increased type L HSL activity from 72 +/- 1 to 96 +/- 1 U/g wet wt tissue (P less than 0.001) in the myocardium. At the same time, cardiac TG stores decreased from 1.83 +/- 0.03 to 1.37 +/- 0.01 mumol/g tissue (P less than 0.001). In a separate experiment, one night of eating a fat-rich diet (60% of calories from fat) caused a 42% increase in type L HSL activity, which was accompanied by a 42% reduction in the TG content of the heart. Likewise cold exposure (overnight) activated type L HSL (73%) and, at the same time, decreased cardiac TG stores (44%). When data from the fasting, fat-feeding, and cold-exposure experiments were combined, a significant correlation coefficient of -0.81 was obtained between type L HSL activity and TG content of the heart (P less than 0.001). These data provide evidence for a physiological relationship between intracellular lipoprotein lipase activity and cardiac TG content.
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PMID:Relationship between type L hormone-sensitive lipase and endogenous triacylglycerol in rat heart. 649 11

The human hormone-sensitive lipase (HSL) gene encodes a 786-aa polypeptide (85.5 kDa). It is composed of nine exons spanning approximately 11 kb, with exons 2-5 clustered in a 1.1-kb region. The putative catalytic site (Ser423) and a possible lipid-binding region in the C-terminal part are encoded by exons 6 and 9, respectively. Exon 8 encodes the phosphorylation site (Ser551) that controls cAMP-mediated activity and a second site (Ser553) that is phosphorylated by 5'-AMP-activated protein kinase. Human HSL showed 83% identity with the rat enzyme and contained a 12-aa deletion immediately upstream of the phosphorylation sites with an unknown effect on the activity control. Besides the catalytic site motif (Gly-Xaa-Ser-Xaa-Gly) found in most lipases, HSL shows no homology with other known lipases or proteins, except for a recently reported unexpected homology between the region surrounding its catalytic site and that of the lipase 2 of Moraxella TA144, an antarctic psychrotrophic bacterium. The gene of lipase 2, which catalyses lipolysis below 4 degrees C, was absent in the genomic DNA of five other Moraxella strains living at 37 degrees C. The lipase 2-like sequence in HSL may reflect an evolutionarily conserved cold adaptability that might be of critical survival value when low-temperature-mobilized endogenous lipids are the primary energy source (e.g., in poikilotherms or hibernators). The finding that HSL at 10 degrees C retained 3- to 5-fold more of its 37 degrees C catalytic activity than lipoprotein lipase or carboxyl ester lipase is consistent with this hypothesis.
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PMID:Gene organization and primary structure of human hormone-sensitive lipase: possible significance of a sequence homology with a lipase of Moraxella TA144, an antarctic bacterium. 850 34

A psychrotrophic bacterium producing a cold-adapted lipase upon growth at low temperatures was isolated from Alaskan soil and identified as a Pseudomonas strain. The lipase gene (lipP) was cloned from the strain and sequenced. The amino acid sequence deduced from the nucleotide sequence of the gene (924 bp) corresponded to a protein of 308 amino acid residues with a molecular weight of 33,714. LipP also has consensus motifs conserved in other cold-adapted lipases, i.e., Lipase 2 from Antarctic Moraxella TA144 (G. Feller, M. Thirty, J. L. Arpigny, and C. Gerday, DNA Cell Biol. 10:381-388, 1991) and the mammalian hormone-sensitive lipase (D. Langin, H. Laurell, L. S. Holst, P. Belfrage, and C. Holm, Proc. Natl. Acad. Sci. USA 90:4897-4901, 1993): a pentapeptide, GDSAG, containing the putative active-site serine and an HG dipeptide. LipP was purified from an extract of recombinant Escherichia coli C600 cells harboring a plasmid coding for the lipP gene. The enzyme showed a 1,3-positional specificity toward triolein. p-Nitrophenyl esters of fatty acids with short to medium chains (C4 and C6) served as good substrates. The enzyme was stable between pH 6 and 9, and the optimal pH for the enzymatic hydrolysis of tributyrin was around 8. The activation energies for the hydrolysis of p-nitrophenyl butyrate and p-nitrophenyl laurate were determined to be 11.2 and 7.7 kcal/mol, respectively, in the temperature range 5 to 35 degrees C. The enzyme was unstable at temperatures higher than 45 degrees C. The Km of the enzyme for p-nitrophenyl butyrate increased with increases in the assay temperature. The enzyme was strongly inhibited by Zn2+, Cu2+, Fe3+, and Hg2+ but was not affected by phenylmethylsulfonyl fluoride and bisnitrophenyl phosphate. Various water-miscible organic solvents, such as methanol and dimethyl sulfoxide, at concentrations of 0 to 30% (vol/vol) activated the enzyme.
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PMID:A cold-adapted lipase of an Alaskan psychrotroph, Pseudomonas sp. strain B11-1: gene cloning and enzyme purification and characterization. 946 82

Mammalian hormone-sensitive lipase (HSL) has given its name to a family of primarily prokaryotic proteins which are structurally related to type B carboxylesterases. In many of these alpha/beta hydrolases, a conserved HG-dipeptide flanks the catalytic pocket. In HSL this dipeptide is followed by two additional glycine residues. Through site-directed mutagenesis, we have investigated the importance of this motif for enzyme activity. Since the presence of multiple glycine residues in a critical region could contribute to cold adaptation by providing local flexibility, we studied the effect of mutating these residues on the psychrotolerant property of HSL. Any double mutation rendered the enzyme completely inactive, without any major effect on the enzyme stability. The partially active single mutants retained the same proportion of activity at reduced temperatures as the wild-type enzyme. These results do not support a role for the HGGG motif in catalysis at low temperatures, but provide further validation of the current three-dimensional model of HSL. Rat HSL was found to be relatively more active than human HSL at low temperatures. This difference was, however, not due to the 12 amino acids which are present in the regulatory module of the rat enzyme but absent in human HSL.
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PMID:Analysis of the psychrotolerant property of hormone-sensitive lipase through site-directed mutagenesis. 1111 10

The selective mobilization of fatty acids from white fat cells depends on their molecular structure, in particular the degree of unsaturation. The present study was designed to examine if the release of fatty acids by hormone-sensitive lipase (HSL) in vitro i) is influenced by the amount of unsaturation, ii) depends on the temperature, and iii) could explain the selective pattern of fatty acid mobilization and notably the preferential mobilization of certain highly unsaturated fatty acids. Recombinant rat and human HSL were incubated with a lipid emulsion. The hydrolysis of 35 individual fatty acids, ranging in chain length from 12 to 24 carbon atoms and in unsaturation from 0 to 6 double bonds was measured. Fatty acid composition of in vitro released NEFA was compared with that of fat cell triacylglycerols (TAG), the ratio % NEFA/% TAG being defined as the relative hydrolysis. The relative hydrolysis of individual fatty acids differed widely, ranging from 0.44 (24:1n-9) to 1.49 (18:1n-7) with rat HSL, and from 0.38 (24:1n-9) to 1.67 (18:1n-7) with human HSL. No major difference was observed between rat and human HSL. The relative release was dependent on the number of double bonds according to chain length. The amount of fatty acid released by recombinant rat HSL was decreased but remained robust at 4 degrees C compared with 37 degrees C, and the relative hydrolysis of some individual fatty acids was affected. The relative hydrolysis of fatty acids moderately, weakly, and highly mobilized by adipose tissue in vivo was similar and close to unity in vitro. We conclude that i) the release of fatty acids by HSL is only slightly affected by their degree of unsaturation, ii) the ability of HSL to efficiently and selectively release fatty acids at low temperature could reflect a cold adaptability for poikilotherms or hibernators when endogenous lipids are needed, and iii) the selectivity of fatty acid hydrolysis by HSL does not fully account for the selective pattern of fatty acid mobilization, but could contribute to explain the preferential mobilization of some highly unsaturated fatty acids compared with others.
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PMID:Fatty acid specificity of hormone-sensitive lipase. Implication in the selective hydrolysis of triacylglycerols. 1173 78

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a highly conserved hormone. Targeted disruption of the PACAP gene has revealed a role for this peptide in lipid metabolism, carbohydrate metabolism, and the sympathetic response to insulin stress. We report here that PACAP null mice are temperature sensitive. When raised at 21 C, only 11% of the PACAP null mice survived past the first 2 wk after birth, but when raised at 24 C, most (76%) of the PACAP null mice survived. The question is the mechanism by which the absence of PACAP affects thermoregulation. Brown adipose tissue is the major site of adaptive thermogenesis in neonates and rodents. We show that PACAP null mice have brown adipocytes that differentiate normally and express two enzymes involved in thermogenesis, hormone-sensitive lipase and uncoupling protein 1. Likewise, levels of catecholamines in the adrenal medulla and plasma are normal in PACAP null mice raised at a lower temperature. In contrast, norepinephrine and its precursor dopamine extracted from brown adipose tissue are present at significantly lower levels in the PACAP null mice compared with controls. Also, PACAP null mice showed a greater loss of core body temperature compared with wild-type controls at 21 C. We conclude that under prolonged but mild cold stress, lack of PACAP results in inadequate heat production due to insufficient norepinephrine stimulation of brown adipose tissue.
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PMID:Temperature-sensitive phenotype in mice lacking pituitary adenylate cyclase-activating polypeptide. 1223 80

The gene encoding an esterase (PsyEst) of Psychrobacter sp. Ant300, a psychrophilic bacterium isolated from Antarctic soil, was cloned, sequenced, and expressed in Escherichia coli. PsyEst, which is a member of hormone-sensitive lipase (HSL) group of the lipase/esterase family, is a cold-active, themolabile enzyme with high catalytic activity at low temperatures (5-25 degrees C), low activation energy (e.g., 4.6 kcal/mol for hydrolysis of p-nitrophenyl butyrate), and a t(1/2) value of 16 min for thermal inactivation during incubation at 40 degrees C and pH 7.9. A three-dimensional structural model of PsyEst predicted that Gly(244) was located in the loop near the active site of PsyEst and that substitution of this amino-acid residue by proline should potentially rigidify the active-site environment of the enzyme. Thus, we introduced the Gly(244)-->Pro substitution into the enzyme. Stability studies showed that the t(1/2) value for thermal inactivation of the mutant during incubation at 40 degrees C and pH 7.9 was 11.6 h, which was significantly greater than that of the wild-type enzyme. The k(cat)/K(m) value of the mutant was lower for all substrates examined than the value of the wild type. Moreover, this amino-acid substitution caused a shift of the acyl-chain length specificity of the enzyme toward higher preference for short-chain fatty acid esters. All of these observations could be explained in terms of a decrease in active-site flexibility brought about by the mutation and were consistent with the hypothesis that cold activity and thermolability arise from local flexibility around the active site of the enzyme.
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PMID:Cold-active esterase from Psychrobacter sp. Ant300: gene cloning, characterization, and the effects of Gly-->Pro substitution near the active site on its catalytic activity and stability. 1472 5

The ability to store energy in the form of energy-dense TAG (triacylglycerol) and to mobilize these stores rapidly during times of low carbohydrate availability (fasting or famine) or during heightened metabolic demand (exercise or cold-stress) is a highly conserved process essential for survival. Today, in the presence of nutrient excess and sedentary lifestyles, the regulation of this pathway is viewed as an important therapeutic target for disease prevention, as elevated circulating fatty acids in obesity contribute to many aspects of the metabolic syndrome including hepatic steatosis, atherosclerosis and insulin resistance. In the present review, we discuss the metabolic regulation and function of TAG lipases with a focus on HSL (hormone-sensitive lipase), ATGL (adipose triacylglycerol lipase) and newly identified members of the lipolytic proteome.
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PMID:Regulation and function of triacylglycerol lipases in cellular metabolism. 1871 47

Two esterase genes (designated as estAT1 and estAT11, respectively) were cloned by activity-based screening of a fosmid library constructed with seashore sediment sample of the Arctic. The sequence analysis of the genes revealed that these esterase genes encoded proteins of 303 and 312 amino acids, respectively, and showed 40-50% identities to members of the hormone-sensitive lipase (HSL) family retaining a catalytic triad with a conserved GDSAG sequence and an oxyanion hole (HGGG). The esterases genes were overexpressed in Escherichia coli by co-expressing GroEL-GroES chaperonine, and the recombinant proteins (rEstAT1 and rEstAT11) were purified to homogeneity. The purified EstAT1 and EstAT11 were active in a broad range of temperature from 20 to 40 degrees C with an optimum temperature at 30 degrees C. The activation energies of rEstAT1 and rEstAT11 to hydrolyze p-nitrophenyl esters of butyrate were determined to be 12.65 kcal/mol and 11.26 kcal/mol, respectively, indicating that they are cold-adapted esterases. The purified EstAT1 and EstAT11 could hydrolyze racemic ofloxacin esters, and further rEstAT11 hydrolyzed preferentially (S)-racemic ofloxacin butyl ester with an enantiomeric excess (ee(p)) value of 70.3%. This work represents an example that develops enzymes from the Arctic using metagenomic approach, potentially applicable to chiral resolution of heat-labile substrates.
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PMID:Characterization and its potential application of two esterases derived from the arctic sediment metagenome. 1881 17

Cold-adapted esterases and lipases have been found to be dominant activities throughout the cold marine environment, indicating their importance in bacterial degradation of the organic matter. lip2 Gene from Psychrobacter sp. TA144, a micro-organism isolated from the Antarctic sea water, was cloned and over-expressed in Escherichia coli. The recombinant protein (PsyHSL) accumulated in the insoluble fraction from which it was recovered in active form, purified to homogeneity and deeply characterised. Temperature dependence of PsyHSL activity was typical of psychrophilic enzymes, with an optimal temperature of 35 degrees C at pH 8.0. The enzyme resulted to be active on pNP-esters of fatty acids with acyl chain length from C(2) to C(12) and the preferred substrate was pNP-pentanoate showing a k(cat) = 26.2 +/- 0.1 s(-1), K(M) = 0.122 +/- 0.006 mM and a k(cat)/K(M) = 215 +/- 11 mM(-1) s(-1). The enzyme was strongly inhibited by Hg(2+), Zn(2+), Cu(2+), Fe(3+), Mn(2+) ions and it resulted to be activated in presence of methanol and acetonitrile, with calculated C(50) values of 1.98 M and 0.92 M, respectively. The region surrounding PsyHSL catalytic site showed an unexpected homology with the human HSL. Further, both enzymes are characterised by the presence of an extra N-terminal domain, which role in the human protein has been related to regulative function. To clarify the function of PsyHSL N-terminal domain, a 97 amino acids deleted version of the enzyme was produced in E. coli in soluble form, purified and characterised. This mutant was inactive towards all tested substrates, indicating the involvement of this region in the catalytic process.
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PMID:The hormone-sensitive lipase from Psychrobacter sp. TA144: new insight in the structural/functional characterization. 2038 98


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