Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.3.3.1 (citrate synthase)
 4,488 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A simple method is presented for the analysis of protein conformational changes based on the comparison of torsion angles defined by four consecutive C alpha atoms. The technique was applied successfully to proteins that undergo hinge motion and shear motion. In the case of both MBP and LAO, which represent examples of hinge motion, the plot of the differences in C alpha-torsion angles between the open and closed forms of the proteins helped us to formulate a more thorough description of the conformational change: a large displacement of one domain with respect to the other where one of the domains does not behave like a rigid body but exhibits some degree of flexibility. The analysis of citrate synthase, which is an example of shear motion, shows that the largest differences in C alpha-torsion angles between the open and closed conformations are clustered around residues that belong to segments connecting alpha-helices, whereas the helices themselves appear to be rigid; this is in agreement with previous results obtained by detailed least-squares superpositions (Lesk AM, Chothia C, 1984, J Mol Biol 174:175-191).
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PMID:C alpha-based torsion angles: a simple tool to analyze protein conformational changes. 853 48

A condition similar to insulin-dependent diabetes mellitus (IDDM) was induced in male CD-1 mice by injection of streptozotocin (STZ). Five weeks after treatment, the fast-twitch extensor digitorum longus (EDL) and slow-twitch soleus (SOL) muscles were isolated for analysis. Phosphorous metabolites were quantified by 31P-NMR and HPLC, native myosin was characterized electrophoretically, and activities of metabolic enzymes were measured spectrophotometrically. Relative to control animals, STZ-diabetes resulted in a significant 32% decrease in the FM1 isoform of myosin in EDL and a 24% decrease in IM myosin of SOL. Mass-specific activities of phosphofructokinase, citrate synthase, and cytochrome oxidase were significantly lower in SOL from STZ-diabetic mice than in controls by 23, 18, and 36%, respectively. Intracellular ATP was significantly lower in SOL from STZ-diabetic mice than in controls (3.44 +/- 0.20 mumol g-1 wet weight vs. 4.61 +/- 0.20 mumol g-1, respectively), as was creatine phosphate (11.98 +/- 0.80 mumol g-1 wet weight vs. 14.22 +/- 0.44 mumol g-1). In contrast to results from SOL, there were no significant changes in phosphorus metabolites or enzyme activity in EDL. These results show that the effects of IDDM on levels of phosphorus containing metabolites and maximal activities of key regulatory enzymes in muscle are markedly fiber-type specific. It is suggested that the muscle type-specific effects of STZ-diabetes may be a consequence of differential accumulation of intracellular fatty acids.
Mol Cell Biochem 1995 Jul 19
PMID:Responses of mouse fast and slow skeletal muscle to streptozotocin diabetes: myosin isoenzymes and phosphorous metabolites. 859 19

We previously demonstrated that feeding rats the Steenbock and Black rickets-inducing diet produces remarkable changes in the metabolic pattern of intestinal mucosa, kidney, liver, cerebral cortex and heart. We have now determined the levels of calcium, phosphorus and citrate in cerebral cortex and the activity of some enzymes in synaptosomes and cerebral cortex mitochondria of three rat groups: control (Group A), fed a vitamin D-deficient diet (Group B), fed a vitamin D-deficient diet and treated with 1,25-dihydroxyvitamin D3 (Group C). While calcium content increased in Groups B and C, phosphorus concentration increased only in Group C and citrate in Group B in comparison with control. The increase in acetylcholinesterase and citrate synthase registered in Group B was restored to control values by 1,25-dihydroxyvitamin D3 treatment, while, neither the decrease in cytochrome c oxidase, nor the increase in glucose-6-phosphate dehydrogenase, acid phosphatase and NADP+(-)isocitrate dehydrogenase observed in Group B were corrected by 1,25-dihydroxyvitamin D3 supply. Acyl phosphatase showed a remarkable increase in consequence of 1,25-dihydroxyvitamin D3 administration.
Biochem Mol Biol Int 1995 Nov
PMID:Vitamin D--related modification of enzyme activities in synaptosomes and mitochondria isolated from rat cerebral cortex. 862 85

Pummelo (Citrus maxima [Burm.] Merrill) cDNAs encoding mitochondrial citrate synthase (mCS) were cloned by reverse transcription of juice-sac poly(A)+ mRNA, followed by Taq Polymerase-mediated amplification. The nucleotide sequence of the citrus gene (cit1) is 77% conserved relative to plant mRNAs for mCS. The encoded polypeptide includes a mitochondrial targeting signal at its amino terminus; all 20 putative active-site residues of the citrus enzyme are conserved. Southern hybridization showed that citrus cit1 is a single-copy gene. A polymorphism associated with cit1 did not cosegregate with fruit acidity indicating that acitric, the gene causing the acidless phenotype of pummelo 2240, is not an allele of cit1 locus. Quantitative detection of cit1 mRNA showed that transcript levels are not developmentally regulated in juice sacs; no differences were observed between high- and low-acid genotypes.
Plant Mol Biol 1996 Apr
PMID:Molecular characterization of the mitochondrial citrate synthase gene of an acidless pummelo (Citrus maxima). 870 47

Mitochondrial enzyme activities were examined in cardiac tissues of turkeys with spontaneous inbred cardiomyopathy. Marked declines in specific enzyme activities were noted for respiratory complexes III and V ranging from 65-90% of the control values. No significant differences in complexes I, IV and citrate synthase nor in mitochondrial DNA copy number were detected. These results suggest that specific mitochondrial enzyme defects occur in cardiac tissues during spontaneous inbred turkey cardiomyopathy.
Biochem Mol Biol Int 1996 May
PMID:Mitochondrial dysfunction in spontaneous inbred turkey cardiomyopathy. 873 29

A cDNA clone for 3-ketoacyl-CoA thiolase (EC 2.3.1.16) was isolated from a lambda gt11 cDNA library constructed from the poly(A)+ RNA of etiolated pumpkin cotyledons. The cDNA insert contained 1682 nucleotides and encoded 461 amino acid residues. A study of the expression in vitro of the cDNA and analysis of the amino-terminal sequence of the protein indicated that pumpkin thiolase is synthesized as a precursor which has a cleavable amino-terminal presequence of 33 amino acids. The amino-terminal presequence was highly homologous to typical amino-terminal signals that target proteins to microbodies. Immunoblot analysis showed that the amount of thiolase increased markedly during germination but decreased dramatically during the light-inducible transition of microbodies from glyoxysomes to leaf peroxisomes. By contrast, the amount of mRNA increased temporarily during the early stage of germination. In senescing cotyledons, the levels of the thiolase mRNA and protein increased again with the reverse transition of microbodies from leaf peroxisomes to glyoxysomes, but the pattern of accumulation of the protein was slightly different from that of malate synthase. These results indicate that expression of the thiolase is regulated in a similar manner to that of other glyoxysomal enzymes, such as malate synthase and citrate synthase, during seed germination and post-germination growth. By contrast, during senescence, expression of the thiolase is regulated in a different manner from that of other glyoxysomal enzymes.
Plant Mol Biol 1996 Jul
PMID:cDNA cloning and expression of a gene for 3-ketoacyl-CoA thiolase in pumpkin cotyledons. 880 14

Changes in the capacities of ATP-synthesizing reactions were analysed in residual non-infarcted myocardium following myocardial infarction. Rats were subjected to left coronary artery ligation (MI; n = 11) or to sham operation (sham; n = 18). Two months later, hearts were excised, rinsed and buffer-perfused isovolumically. In vitro pressure-volume relationships were recorded. After separation into left and right ventricles (LV, RV) and atria (LA, RA), samples were analysed for citrate synthase, glycolytic enzymes (phosphofructokinase, glyceraldehyde-3-phosphate-dehydrogenase, lactate dehydrogenase (LDH) and its isoforms) and the creatine kinase (CK) system [total CK, CK isoenzymes (CKBB, CKMB, CKMM and CKmito) and total creatine]. In residual intact heart, citrate synthase activity and activities of most glycolytic enzymes were unchanged, but LDH activity and anaerobic LDH isoenzymes increased significantly. Total creatine kinae activity (6.5 +/- 0.2 IU/mg protein in sham LV) was decreased by chronic myocardial infarction in LV (5.4 +/- 0.3, with P < 0.05 sham v MI) but not in RV (6.2 +/- 0.2). Significant CK isoenzyme shifts occurred in both ventricles "adult" CKmito (32.5 +/- 1.4% in sham LV) was reduced in LV (22.1 +/- 2.1% with P < 0.05 sham v MI) and in RV (19.2 +/- 2.9%, with P < 0.05 sham v MI), "fetal" CKBB and CKMB increased. Total creatine content was reduced by up to 35% in both ventricles. In sham hearts atria had lower total and mitochondrial CK activity, lower total creatine content and higher CKMB and CKBB activity compared to ventricles; however, myocardial infarction induced changes directionally comparable to the changes observed in ventricles. Thus, 2 months after myocardial infarction changes of the capacities of ATP synthesizing reactions are comparable for all heart chambers, with the exception of total CK activity decreasing only in left ventricular tissue.
J Mol Cell Cardiol 1996 Jul
PMID:Regional biochemical remodeling in non-infarcted tissue of rat heart post-myocardial infarction. 884 40

The requirement for a rapid and easy method of preparing mitochondrial fractions from cultured skin fibroblasts led us to compare the results obtained from such a preparation with the more traditional methods of cellular fractionation. Values for NADH-cytochrome c reductase (rotenone sensitive) were compared for a series of three controls and nine patients with complex I (NADH-coenzyme Q reductase deficiency). Values obtained for deficient cell lines varied from 19 to 64% of the control values for the long mitochondrial preparation method and from 34 to 70% of control for the rapid preparation. Mean values were statistically significantly different from the lowest control cell line (P < 0.01) in all cases. The specific activity on the basis of activity per milligram of mitochondrial protein and of activity per unit of citrate synthase activity was lower in the rapid preparation of mitochondria by some 41%, indicating a lesser degree of mitochondrial purification. However, the overall result showed that this type of rapid preparation, which uses four 9-cm petri dishes of cultured cells, can be used to diagnose mitochondrial complex I deficiency. This method will find general use in the measurement of either mitochondrial enzymes of low specific activity or mitochondrial enzymes whose measurement is made difficult by contaminating nonmitochondrial enzymes.
Biochem Mol Med 1996 Dec
PMID:Diagnosis of complex I deficiency in patients with lactic acidemia using skin fibroblast cultures. 898 35

The expression of some nuclear genes in Saccharomyces cerevisiae, such as the CIT2 gene, which encodes a glyoxylate cycle isoform of citrate synthase, is responsive to the functional state of mitochondria. Previous studies identified a basic helix-loop-helix-leucine zipper (bHLH/Zip) transcription factor encoded by the RTG1 gene that is required for both basal expression of the CIT2 gene and its increased expression in respiratory-deficient cells. Here, we describe the cloning and characterization of RTG3, a gene encoding a 54-kDa bHLH/Zip protein that is also required for CIT2 expression. Rtg3p binds together with Rtg1p to two identical sites oriented as inverted repeats 28 bp apart in a regulatory upstream activation sequence element (UASr) in the CIT2 promoter. The core binding site for the Rtg1p-Rtg3p heterodimer is 5'-GGTCAC-3', which differs from the canonical E-box site, CANNTG, to which most other bHLH proteins bind. We demonstrate that both of the Rtg1p-Rtg3p binding sites in the UAS(r) element are required in vivo and act synergistically for CIT2 expression. The basic region of Rtg3p conforms well to the basic region of most bHLH proteins, whereas the basic region of Rtg1p does not. These findings suggest that the Rtg1p-Rtg3p complex interacts in a novel way with its DNA target sites.
Mol Cell Biol 1997 Mar
PMID:A basic helix-loop-helix-leucine zipper transcription complex in yeast functions in a signaling pathway from mitochondria to the nucleus. 903 38

This study examined the organization of the Krebs tricarboxylic acid (TCA) cycle by metabolic engineering and high-resolution 13C NMR. The oxidation of [1,2,3-13C]propionate to glutamate via the TCA cycle was measured in wild-type (WT) and a citrate synthase mutant (CS-) strain of Escherichia coli transformed with allosteric E. coli citrate synthase (ECCS) or non-allosteric pig citrate synthase (PCS). The 13C fractional enrichment in glutamate C-2, C-3, and C-4 in ECCS and PCS were similar; although quantitative differences in total citrate synthase activity and total C-4 labeling of glutamate were observed in ECCS and PCS. Allosteric ECCS cells contained 10-fold less total enzyme activity than PCS but only 50% less total labeling in glutamate C-4 and equivalent doubling times. The observed spectra were mathematically fitted using an iterative procedure (TCACALC) and yielded an acetate/succinyl-CoA flux ratio of 10 for both ECCS and PCS, a result that is in agreement with the isotopomer analyses of the 13C spectra of cells presented with [3-13C]propionate or [2-13C]propionate. The results are consistent with the presence of an allosteric citrate synthase in ECCS and a non-allosteric citrate synthase in PCS. The former maintains TCA cycle flux via alternative propionate pathways activated by positive allosteric mechanisms and the latter via elevated enzyme levels.
J Mol Recognit
PMID:Metabolic engineering of a non-allosteric citrate synthase in an Escherichia coli citrate synthase mutant. 905 73


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