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Query: UNIPROT:P06889 (Mol)
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Eleven soluble enzymes in the supernatant of bloodstream Trypanosoma brucei were compared for electrophoretic mobility and activity with those of T. brucei cultures grown in 3 different media. All bands of each enzyme found in the bloodstream form were also present in the cultured material, but extra bands of malate dehydrogenase (MDH) (EC 1.1.1.37), aspartate aminotransferase (ASAT) (EC 2.6.1.1), and in 2 to 6 cultures of isocitrate dehydrogenase (ICD) (EC 1.1.1.42) were present in culture forms but not in bloodstream forms. An interfering enzyme, peculiar to cultured T. brucei, which reacted with 2-oxoglutarate and possibly a trace amount of ammonium ions, ran with the fast-moving ASAT bands. Threonine dehydrogenase activity, high in cultured trypanosomes irrespective of the medium used but low in bloodstream trypanosomes, was markedly lower in Trypanosoma evansi and a much passaged T. brucei 8/18. Glucosephosphate isomerase activity on the other hand was high in bloodstream and low in cultured trypanosomes. Glutamate dehydrogenase activity was too low to record reliably in bloodstream trypanosomes, but could be clearly detected in cultured forms. As the differences point to some changes in gene expression between the two forms, culture material is likely to replace trypanosomes from living animals for electrophoretic characterization only when considerable comparative work has been done.
Mol Biochem Parasitol 1980 Oct
PMID:The electrophoretic mobilities and activities of eleven enzymes of bloodstream and culture forms of Trypanosoma brucei compared. 645 Aug 96

The model of a reversible reaction catalyzed by an oligomeric enzyme has been investigated. The regions of parameter values have been estimated at which the model describes "unidirectional" or alternative effects of allosteric modifiers on the rates of forward and backward reactions. The plausible explanation and mathematical description are offered for kinetic and regulatory peculiarities of reversible reactions catalyzed by NAD-dependent isocitrate dehydrogenase and catabolic ornithine carbamoylphosphate transferase. The phenomena of unidirectional catalysis of alternative directions of a reversible reaction by different enzymes are considered.
Mol Biol (Mosk)
PMID:[Kinetic and regulatory properties of reversible enzymic reactions]. 725 8

Vitamin D3 administration affects the NAD-linked oxidoreductase activities of Krebs cycle from intestinal mucosa of vitamin D-deficient chicks. Vmax values were increased in all of them, while K0.5 for substrate remained unchanged except for 2-oxoglutarate dehydrogenase, which showed lower affinity for oxoglutarate. Addition of Ca2+ to the incubation medium increased the affinity of 2-oxoglutarate dehydrogenase and NAD-isocitrate dehydrogenase for their substrates either in the vitamin D3 treated group or in the control one. The activity of succinate dehydrogenase, a FMN-dependent oxidoreductase, was not modified by vitamin D3 administration. The oxygen consumption of the intestinal mitochondria was not altered by cholecalciferol treatment to vitamin D-deficient chicks. The reason why vitamin D3 selectively affects the NAD-linked oxidoreductase activities of the Krebs cycle remains unknown. The vitamin D hormone, 1,25(OH)2D3, appears to be the mediator of the response.
Biochem Mol Biol Int 1995 Jul
PMID:Vitamin D affects Krebs cycle NAD-linked oxidoreductases from chick intestinal mucosa. 754 52

In the adipose tissue, besides fatty acid synthesis (FA-S) from glucose, which includes several mitochondrial steps, FA-S from glutamate has been demonstrated. FA-S from glutamate takes place in the cytosol through the backward pathway of Krebs cycle (BPKC) and is due to the sequential action of (1) alanine aminotransferase (ALT, EC 2.6.1.2), which is presence of pyruvate converts glutamate to oxoglutarate; (2) isocitrate dehydrogenase (NADP) (ICDH, EC 1.1.1.42), which converts oxoglutarate to isocitrate; (3) aconitate hydratase (ACO, EC 4.2.1.3), which transforms isocitrate to citrate: and (4) ATP citrate-lyase (ATP-CL, EC 4.1.3.8), which splits citrate to yield the acetyl-CoA needed for FA-S. We studied the enzymes involved in BPKC in homogenates of human adipose tissue. In normal subjects, the cytosolic activity (mumol/min/g protein) was: ALT = 10.3 +/- 1.1, ICDH = 29.5 +/- 2.8, ACO = 2.05 +/- 0.23, and ATP-CL = 1.2 +/- 0.2. Mitochondria contained less or no activity, values being 20, 9, 11, and 0% of total for ATL, ICDH, ACO, and ATP-CL, respectively. BPKC enzymes are more active than the enzymes limiting FA-S from glucose, i.e., phosphofructokinase (EC 2.7.1.11), pyruvate carboxylase (EC 6.4.1.1), and pyruvate dehydrogenase (EC 1.2.4.1). In the obese patients, cytosolic ALT and ATP-CL were increased (12.9 +/- 0.7, P < 0.05, and 2.28 +/- 0.27, P < 0.01, respectively) compared to normal, while ICDH was not changed (ACO could not be studied). Similar changes were obtained by expressing enzyme activity per fat cell number.(ABSTRACT TRUNCATED AT 250 WORDS)
Biochem Mol Med 1995 Feb
PMID:Fatty acid synthesis from glutamate in the adipose tissue of normal subjects and obese patients: an enzyme study. 755 12

The effect of DL alpha-lipoic acid on the nephrotoxic potential of gentamicin was examined. Intraperitoneal injection of gentamicin (100 mg/kg/day) to rats resulted in decreased activity of the glycolytic enzymes-hexokinase, phosphoglucoisomerase, aldolase and lactate dehydrogenase. The two gluconeogenic enzymes--glucose-6-phosphatase and fructose-1,6-diphosphatase, the transmembrane enzymes namely the Na+, K(+)-ATPase, Ca(2+)-ATPase, Mg(2+)-ATPase and the brushborder enzyme alkaline phosphatase, also showed decreased activities. This decrease in the activities of ATPases and alkaline phosphatase suggests basolateral and brush border membrane damage. Decreased activity of the TCA cycle enzymes isocitrate dehydrogenase (ICDH), succinate dehydrogenase (SDH) and malate dehydrogenase (MDH), suggests a loss in mitochondrial integrity. These biochemical disturbances were effectively counteracted by lipoic acid administration. Lipoic acid administration by gastric intubation at two different concentrations (10 mg and 25 mg/kg/day) brought about an increase in the activity of the glycolytic enzymes, ATPases and the TCA cycle enzymes. The gluconeogenic enzymes however showed a further decrease in their activities at both the concentrations of lipoic acid administered. These observations shed light on the nephroprotective action of lipoic acid against experimental aminoglycoside toxicity and the protection afforded at 25 mg/kg/day of lipoic acid was noted to be higher than that at 10 mg level.
Mol Cell Biochem 1995 Apr 12
PMID:Role of DL alpha-lipoic acid in gentamicin induced nephrotoxicity. 765 73

The purpose of this study was to investigate whether vitamin D3 deficiency and 1,25-dihydroxyvitamin D3 treatment affect some aspects of heart metabolism in the rat. To this end, five experimental groups were studied: (1) the control group of the vitamin D3 supplemented rats (Group A); (2) rachitic rats (Group B); (3) rachitic rats treated with 1,25-dihydroxyvitamin D3 (Group C); (4) rats fed a vitamin D-deficient diet (Group D); (5) rats fed a vitamin D-deficient diet and treated with 1,25-dihydroxyvitamin D3 (Group E). The five groups were compared by checking in the heart some metabolic parameters, i.e. citrate content, and enzyme activities in cytosol and mitochondria. Citrate content was higher in the heart of treated animals when compared with the control. As regards the enzymatic activities in heart mitochondria, NAD(+)-dependent isocitrate dehydrogenase remarkably decreased in Group B rats and 1,25-dihydroxyvitamin D3 restored quite normal values. NADP(+)-dependent isocitrate dehydrogenase decreased in Group B and Group D animals, and 1,25-dihydroxyvitamin D3 treatment was effective in restoring control values. Cytochrome c oxidase activity did not change, while citrate synthase showed an increase in all the treated rats. As regards the cytosolic enzymes, fructose-6-phosphate kinase increased in the two groups of vitamin D-deplete rats in comparison with the control. Glyceraldehyde-3-phosphate dehydrogenase and 3-phosphoglycerate kinase showed a similar trend: an increase in all the treated animals. In heart homogenate, acylphosphatase and acid phosphatase activities were also determined. Acylphosphatase increased in the treated rats, while acid phosphatase decreased in the rats injected with 1,25-dihydroxyvitamin D3. These results support the hypothesis of a participation of 1,25-dihydroxyvitamin D3 in some aspects of heart metabolism.
J Mol Cell Cardiol 1994 Nov
PMID:Effect of vitamin D deficiency and 1,25-dihydroxyvitamin D3 on rat heart metabolism. 789 66

Nicotinamide (NIC) is known to increase the synthesis of pyridine nucleotides and also to inhibit the hydrolysis of them to ADP-ribose, which in turn is involved in Ca2+ release from mitochondria via the ADP ribosylation of crucial mitochondrial proteins. In this work, we test the potential ability of NIC to be a late protective agent against CCl4-induced liver necrosis. We observed that 1 g/kg po NIC, 30 min before or 6 or 10 hr after CCl4 (1 ml/kg), given ip as a 20% (v/v) solution in olive oil, was able to significantly prevent the necrogenic effect of the hepatotoxin at 24 hr as evidenced by determination of isocitric dehydrogenase activity in plasma or by histological observation. NIC administration 6 hr after CCl4 prevented fatty liver induced by hepatotoxin at 24 hr. NIC did not modify CCl4-induced lipid peroxidation process at 1 hr after CCl4 and decreased the covalent binding of 14CCl4 to lipids. NIC decreased the levels of 14CCl4 reaching the liver when given 30 min before hepatotoxin but not when given 6 hr after it. NIC lowered body temperature of rats at 1, 3, and 6 hr and augmented it at 24 hr after CCl4. NIC concentrations in liver as determined by GC/MS/SIM analysis were 21 micrograms/g liver 1 hr after administration and 53 micrograms/g at 3 hr. Late preventive effects of NIC against CCl4 induced liver necrosis when given at 6 or 10 hr after CCl4 are compatible with the hypothesis that NIC restores mitochondrial ability for Ca2+ uptake. This hypothesis remains to be proved and is being further challenged in our laboratory.
Exp Mol Pathol 1994 Jun
PMID:Nicotinamide late protective effects against carbon tetrachloride-induced liver necrosis. 795 79

The effects of urea, cations (K+,NH4,Na+,Cs+,Li+), and trimethylamines on the maximal activities and kinetic properties of pyruvate kinase (PK) and phosphofructokinase (PFK) from skeletal muscle were analyzed in two anuran amphibians, an estivating species, the spadefoot toad Scaphiopus couchii, and a semi-aquatic species, the leopard frog Rana pipiens. Urea, which accumulates naturally to levels of 200-300 mM during estivation in toads, had only minor effects on the Vmax, kinetic constants and pH curves of PK from either species and no effects on PFK Vmax or kinetic constants. Trimethylamine oxide neither affected enzyme activity directly or changed enzyme response to urea. By contrast, high KCl (200 mM) lowered the Vmax of toad PFK and of PK from both species and altered the Km values for both substrates of frog PFK. Other cations were even more inhibitory; for example, the Vmax of PK from either species was reduced by more than 80% by the addition of 200 mM NH4Cl, NaCl, CsCi, or LiCl. High KCl also significantly changed the Km values for substrates of toad lactate dehydrogenase and strongly reduced the Vmax of glutamate dehydrogenase and NAD-dependent isocitrate dehydrogenase in both species whereas 300 mM urea had relatively little effect on these enzymes. The perturbing effect of urea on enzymes and the counteracting effect of trimethylamines that has been reported for elasmobranch fishes (that maintain high concentrations of both solutes naturally) does not appear to apply to amphibian enzymes.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Cell Biochem 1994 Feb 09
PMID:Urea and salt effects on enzymes from estivating and non-estivating amphibians. 804 69

We have found a cruciform cutting endonuclease in the yeast, Saccharomyces cerevisiae, which localizes to the mitochondria. This activity apparently is associated with the mitochondrial inner membrane since the activity is not released into solution by osmolysis, in contrast to the matrix enzyme, isocitrate dehydrogenase. The cruciform cutting activity appears to be encoded by CCE1. This gene has been shown to encode one of the major cruciform cutting endonucleases present in yeast cell. In cce1 strains, which lack CCE1 endonuclease activity, the mitochondrial cruciform cutting endonucleolytic activity is also absent. Since CCE1 is allelic to MGT1, a gene required for the highly biased transmission of petite mitochondrial DNA in crosses between rho+ and hypersuppressive rho- cells, it seems likely that the CCE1 endonuclease functions within mitochondria.
Mol Gen Genet 1993 Sep
PMID:Localization of a cruciform cutting endonuclease to yeast mitochondria. 841 91

A cDNA that encodes an NADP-specific isocitrate dehydrogenase (IDH) was cloned from a soybean nodule cDNA library by complementation of an Escherichia coli mutant that lacked IDH. DNA sequence analysis showed that the 1583 bp soybean cDNA could encode a protein that shares 63.9% amino acid sequence identity with the Saccharomyces cerevisiae NADP-IDH and long sequences of identity to an IDH from pig. Southern blot analysis suggests that this gene corresponds to a gene family made up of no more than two loci. The IDH cDNA hybridized to a 1.7 kb soybean mRNA and the relative amount of this transcript in soybean leaves, nodules and roots was 1:3.4:7.7. In alfalfa, a 1.7 kb mRNA was also found but the ratios for the corresponding tissues were 1:7.4:7.7. IDH activity was detected in the complemented E. coli strain and the electrophoretic mobility of this activity in nondenaturing polyacrylamide gels was identical to that of an IDH in extracts from soybean cotyledons or nodule cytosol. NADP-IDH specific activity in the E. coli host strain varied with growth phase; the highest rates (ca. 180 nmol/min per mg protein) were observed in late-stationary-phase cells. The enzyme had a broad pH optimum of 8.0 to 9.5 and had an absolute metal cofactor requirement, preferring Mn2+ below pH 8.0 and Mg2+ above pH 8.0. The Km for isocitrate and NADP was 21 microM and 11 microM respectively with Mn2+ as cofactor and 13 microM and 12 microM with Mg2+ as cofactor.
Plant Mol Biol 1993 Mar
PMID:Isolation and characterization of a cDNA encoding NADP(+)-specific isocitrate dehydrogenase from soybean (Glycine max). 846 73


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