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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A branched-chain acyl-CoA transferase activity which transfers coenzyme A from either 2-methylbutyryl or 2-methylvaleryl-CoA to succinate is present in the muscle mitochondria from the intestinal nematode, Ascaris suum. Its physiological function is discussed. This activity appears to differ from the previously described acetyl-CoA: propionate and propionyl-CoA:succinate acyl-CoA transferases on the basis of heat stability, substrate specificity and the requirement of a "factor" from boiled Ascaris mitochondria for optimal activity of only the branched-chain acyl-CoA transferase. The "factor" has been recovered from HPLC and some of its properties examined. It could not be replaced by a crude soluble fraction from rat liver mitochondria, or by adenine, guanine or inosine di- or triphosphates. Activity was lost upon ashing, but was not affected by treatment with either pepsin or chymotrypsin.
Comp Biochem Physiol Biochem Mol Biol 1994 Aug
PMID:2-Methylbutyryl-CoA: succinate acyl-CoA transferase activity and function in Ascaris suum muscle. 795 70

A fatty acid chain elongation process is involved in incorporation of saturated and unsaturated fatty acyl-CoA esters into 2-tridecanone and (Z)-10-heptadecen-2-one by Drosophila buzzatii. The microsomal fraction from mature male ejaculatory bulbs is chain-length specific and requires malonyl-CoA (or acetyl-CoA, if acetyl-CoA carboxylase were present) for the chain elongation step to 2-ketones. Decarboxylation of the proposed intermediate beta-ketoacid results in 2-ketone biosynthesis. Incubation of the microsomes with the acetyl-CoA carboxylase inhibitor avidin indicated that acetyl-CoA carboxylase was present in the microsomal preparations; however, washing of the microsomal preparation removed the acetyl-CoA carboxylase activity. Fatty acyl-CoA esters were also chain elongated to produce fatty acids two and four carbons longer, suggesting that the enzymes for normal fatty acid chain elongation are also present in the microsomal fraction from ejaculatory bulbs. How much, if any, of this fatty acid chain elongation system is used for 2-ketone biosynthesis is yet to be determined.
Insect Biochem Mol Biol 1994 Sep
PMID:Fatty acid elongation in the biosynthesis of (Z)-10-heptadecen-2-one and 2-tridecanone in ejaculatory bulb microsomes of Drosophila buzzatii. 798 31

Rhizobium species elicit the formation of nitrogen-fixing root nodules through a complex interaction between bacteria and plants. Various bacterial genes involved in the nodulation and nitrogen-fixation processes have been described and most have been localized on the symbiotic plasmids (pSym). We have found a gene encoding citrate synthase on the pSym plasmid of Rhizobium tropici, a species that forms nitrogen-fixing nodules on the roots of beans (Phaseolus vulgaris) and trees (Leucaena spp.). Citrate synthase is a key metabolic enzyme that incorporates carbon into the tricarboxylic acid cycle by catalysing the condensation of acetyl-CoA and oxaloacetic acid to form citrate. R. tropici pcsA (the plasmid citrate synthase gene) is closely related to the corresponding genes of Proteobacteria. pcsA inactivation by a Tn5-mob insertion causes the bacteria to form fewer nodules (30-50% of the original strain) and to have a decreased citrate synthase activity in minimal medium with sucrose. A clone carrying the pcsA gene complemented all the phenotypic alterations of the pcsA mutant, and conferred Rhizobium leguminosarum bv. phaseoli (which naturally lacks a plasmid citrate synthase gene) a higher nodulation and growth capacity in correlation with a higher citrate synthase activity. We have also found that pcsA gene expression is sensitive to iron availability, suggesting a possible role of pcsA in iron uptake.
Mol Microbiol 1994 Jan
PMID:Nodulating ability of Rhizobium tropici is conditioned by a plasmid-encoded citrate synthase. 817 Mar 93

Upon induction of their nodulation genes, the root nodule-inducing Rhizobium bacteria produce lipo-oligosaccharide signal molecules. All lipo-oligosaccharides identified from Rhizobium leguminosarum bv. viciae carry an O-acetyl group at the C-6 position of the non-reducing terminal sugar, the presence of which is important for biological activity and host specificity. Previously we showed that a functional nodL gene product is required for the presence of this O-acetyl moiety. The production of polyclonal antibodies against isolated NodL protein, using a NodL-overproducing Escherichia coli strain is described. These antibodies were used (i) to elucidate the subcellular localization of the NodL protein, which appeared to be present in the cytosol, and (ii) for the purification of native NodL protein from E. coli. Here we provide biochemical proof that purified NodL protein has transacetylating activity in vitro with acetyl-CoA as the acetyl donor. NodL protein appeared to be able to acetylate various substrates, such as lipo-oligosaccharides, chitin fragments and N-acetylglucosamine. For chitinpentaose as the substrate we have shown, using mass spectrometry and NMR spectroscopy, that NodL protein substitutes one O-acetyl group at the C-6 position of the non-reducing terminal sugar.
Mol Microbiol 1994 Feb
PMID:Nodulation protein NodL of Rhizobium leguminosarum O-acetylates lipo-oligosaccharides, chitin fragments and N-acetylglucosamine in vitro. 819 51

DEAE-cellulose chromatography of extracts of free-living Rhizobium meliloti cells revealed separate NAD(+)-dependent and NADP(+)-dependent malic enzyme activities. The NAD+ malic enzyme exhibited more activity with NAD+ as cofactor, but also showed some activity with NADP+. The NADP+ malic enzyme only showed activity when NADP+ was supplied as cofactor. Three independent transposon-induced mutants of R. meliloti which lacked NAD+ malic enzyme activity (dme-) but retained NADP+ malic enzyme activity were isolated. In an otherwise wild-type background, the dme mutations did not alter the carbon utilization phenotype; however, nodules induced by these mutants failed to fix N2. Structurally, these nodules appeared to develop like wild-type nodules up to the stage where N2-fixation would normally begin. These results support the proposal that NAD+ malic enzyme, together with pyruvate dehydrogenase, functions in the generation of acetyl-CoA required for TCA cycle function in N2-fixing bacteroids which metabolize C4-dicarboxylic acids supplied by the plant.
Mol Microbiol 1993 Mar
PMID:NAD(+)-dependent malic enzyme of Rhizobium meliloti is required for symbiotic nitrogen fixation. 838 44

Since acetyl-CoA produced through pyruvate dehydrogenase reaction is poorly oxidized by the Krebs cycle in rat lymphocytes, the fate of acetyl units was investigated in these cells. The results presented here show that 24-h cultured lymphocytes actively synthesize lipids from [3-14C]pyruvate. Furthermore, a considerable amount of these lipids have shown to be exported into the culture medium. Experiments with [1-14C] acetate as a lipid precursor showed a close similarity with the rates of incorporation of [3-14C] pyruvate into the same lipid fractions. Treatment of lymphocytes with the mitogen concanavalin A (Con A) markedly enhanced [1-14C] acetate incorporation into a variety of lipids, but the lectin did not affect [3-14C] pyruvate incorporation. The results suggest that lymphocytes convert pyruvate into lipids via the acetyl-CoA pathway and that Con A interferes in lymphocyte lipogenesis but does not seem to affect the pyruvate dehydrogenase reaction. The ability to incorporate pyruvate into certain lipids may have an important role for the rapidly dividing capacity of lymphocytes since the human cancer strain HeLa 155 (a quickly proliferating cell line) also exhibits this feature by converting much more [3-14C] pyruvate into lipids than do lymphocytes. In addition, comparative experiments with lymphocytes, peritoneal macrophages and HeLa cells indicate that pyruvate may provide precursors for cells with active lipid producing and exporting capacities.
Biochem Mol Biol Int 1993 Jul
PMID:Pyruvate is a lipid precursor for rat lymphocytes in culture: evidence for a lipid exporting capacity. 840 20

The effects of L-carnitine on 14CO2 release from [1-14C]pyruvate oxidation (an index of pyruvate dehydrogenase activity, PDH), [2-14C]pyruvate, and [6-14C]glucose oxidation (indices of the acetyl-CoA flux through citric acid cycle), and [U-14C]glucose (an index of both PDH activity and the flux of acetyl-CoA through the citric acid cycle), were studied using isolated rat cardiac myocytes. L-carnitine increased the release of 14CO2 from [1-14C]pyruvate, and decreased that of [2-14C]pyruvate in a time and concentration-dependent manner. At a concentration of 2.5 mM, L-carnitine produced a 50% increase of CO2 release from [1-14C]pyruvate and a 50% decrease from [2-14C]pyruvate oxidation. L-carnitine also increased CO2 release from [1-14C]pyruvate oxidation by 35%, and decreased that of [2-14C]pyruvate oxidation 30%, in isolated rat heart mitochondria. The fatty acid oxidation inhibitor, etomoxir, stimulated the release of CO2 from both [1-14]pyruvate and [2-14C]pyruvate. These results were supported by the effects of L-carnitine on the CO2 release from [6-14C]- and [U-14C]glucose oxidation. L-carnitine (5 mM) decreased the CO2 release from [6-14C]glucose by 37%, while etomoxir (50 microM) increased its release by 24%. L-carnitine had no effect on the oxidation of [U-14C]glucose. L-carnitine increased palmitate oxidation in a time- and concentration-dependent manner in myocytes. Also, it increased the rate of efflux of acetylcarnitine generated from pyruvate in myocytes. These results suggest that L-carnitine stimulates pyruvate dehydrogenase complex activity and enhances non-oxidative glucose metabolism by increasing the mitochondrial acetylcarnitine efflux in the absence of exogenous fatty acids.
J Mol Cell Cardiol 1995 Nov
PMID:Stimulation of non-oxidative glucose utilization by L-carnitine in isolated myocytes. 859 97

The regulation of fatty acid oxidation in isolated myocytes was examined by manipulating mitochondrial acetyl-CoA levels produced by carbohydrate and fatty acid oxidation. L-carnitine had no effect on the oxidation of [U-14C]glucose, but stimulated oxidation of [1-14C]palmitate in a concentration-dependent manner. L-carnitine (5 mM) increased palmitate oxidation by 37%. The phosphodiesterase inhibitor, enoximone (250 microM), also increased palmitate oxidation by 51%. Addition of L-carnitine to enoximone resulted in a two-fold increase of palmitate oxidation. Whereas, dichloroacetate (DCA, 1 mM), which stimulates PDH activity, decreased palmitate oxidation by 25%. Furthermore, the addition of DCA to myocytes preincubated with either L-carnitine or enoximone, had no effect on the carnitine-induced stimulation of palmitate, and reduced that of enoximone by 50%. Varied concentrations of DCA decreased the oxidation of palmitate and octanoate; but increased glucose oxidation in myocytes. The rate of efflux of acetylcarnitine was highest when pyruvate was present in the medium compared to efflux rates in presence of palmitate or palmitate plus glucose. Although the addition of L-carnitine plus enoximone resulted in a two-fold increase in palmitate oxidation, acetylcarnitine efflux was minimal under these conditions. Acetylcarnitine efflux was highest when pyruvate was present in the medium. These rates were dramatically decreased when myocytes were preincubated with enoximone, despite the stimulation of palmitate oxidation by this compound. These data suggest that: (1) fatty acid oxidation is influenced by acetyl-CoA produced from pyruvate metabolism; (2) L-carnitine may be specific for mitochondrial acetyl-CoA derived from pyruvate oxidation; and (3) it is probable that acetyl-CoA from beta-oxidation of fatty acids is directly channeled into the citric acid cycle.
J Mol Cell Cardiol 1996 May
PMID:Regulation of fatty acid oxidation by acetyl-CoA generated from glucose utilization in isolated myocytes. 876 22

Phosphoenolpyruvate carboxylase (PEPC) genes from Corynebacterium glutamicum (cppc), Escherichia coli (eppc) or Flaveria trinervia (fppc) were transferred to Solanum tuberosum. Plant regenerants producing foreign PEPC were identified by Western blot analysis. Maximum PEPC activities measured in eppc and fppc plants grown in the greenhouse were doubled compared to control plants. For cppc a transgenic plant line could be selected which exhibited a fourfold increase in PEPC activity. In the presence of acetyl-CoA, a known activator of the procaryotic PEPC, a sixfold higher activity level was observed. In cppc plants grown in axenic culture PEPC activities were even higher. There was a 6-fold or 12-fold increase in the PEPC activities compared to the controls measured in the absence or presence of acetyl-CoA, respectively. Comparable results were obtained by transient expression in Nicotiana tabacum protoplasts. PEPC of C. glutamicum (PEPC C.g.) in S. tuberosum leaf extracts displays its characteristic K(m) (PEP) value. Plant growth was examined with plants showing high expression of PEPC and, moreover, with a plant cell line expressing an antisense S. tuberosum (anti-sppc) gene. In axenic culture the growth rate of a cppc plant cell line was appreciably diminished, whereas growth rates of an anti-sppc line were similar or slightly higher than in controls. Malate levels were increased in cppc plants and decreased in antisense plants. There were no significant differences in photosynthetic electron transport or steady state CO2 assimilation between control plants and transformants overexpressing PEPC C.g. or anti-sppc plants. However, a prolonged dark treatment resulted in a delayed induction of photosynthetic electron transport in plants with less PEPC. Rates of CO2 release in the dark determined after a 45 min illumination period at a high proton flux density were considerably enhanced in cppc plants and slightly diminished in anti-sppc plants. When CO2 assimilation rates were corrected for estimated rates of mitochondrial respiration in the light, the electron requirement for CO2 assimilation determined in low CO2 was slightly lower in transformants with higher PEPC, whereas transformants with decreased PEPC exhibited an appreciably elevated electron requirement. The CO2 compensation point remained unchanged in plants (cppc) with high PEPC activity, but might be increased in an antisense plant cell line. Stomatal opening was delayed in antisense plants, but was accelerated in plants overexpressing PEPC C.g. compared to the controls.
Plant Mol Biol 1996 Dec
PMID:Effects of altered phosphoenolpyruvate carboxylase activities on transgenic C3 plant Solanum tuberosum. 898 May 35

Arylalkylamine N-acetyltransferase (NAT; EC2.3.1.87) catalyzes N-acetylation of various arylalkylamines using acetyl-CoA as a donor substrate. A type of NAT was purified 2700-fold from 451 pairs of cockroach testicular organs consisting of testis and its accessory gland. The NAT activity was recovered as a single peak on any column chromatography examined, suggesting that the testicular organ contained only one form of NAT. Five steps of successive column chromatographies gave a single protein band on SDS-polyacrylamide gel electrophoresis with estimated molecular mass of 28 kDa. The molecular mass of the native enzyme was also determined to be approximately 30 kDa by molecular sieve chromatography, indicating that the enzyme is a monomer protein. The enzyme acted on various arylalkylamines such as tryptamine, serotonin, dopamine, octopamine, norepinephrine, tyramine and methoxytryptamine, with K(m) values ranging from 20 to 50 microM. The optimum pH for these substrates was around 6.0. Internal amino acid sequences derived from two proteolytic fragments of the enzyme were determined as Leu-Leu-Gly-Glu-Asn-Gly-Asp-Glu and Phe-Phe-Phe-Leu-Glu-Glu-Pro-Leu-Asn-Ile-Ser-Leu-Gln, both of which exhibited significant homology to the C-terminal sequence of known vertebrate NATs; however, homology was less than 45%. These results suggest that a unique NAT is present in the cockroach testicular organ at high levels, and likely plays a role in the regulation of testicular function.
Insect Biochem Mol Biol 1997 Mar
PMID:Purification and characterization of arylalkylamine N-acetyltransferase from cockroach testicular organs. 909 Jan 19


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