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:1.1.1.41 (isocitrate dehydrogenase)
3,101 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The nucleotide affinity label 2-(4-bromo-2,3-dioxobutylthio)adenosine 5'-diphosphate (2-BDB-TADP) reacts covalently with pig heart NAD+-dependent isocitrate dehydrogenase with a limiting value of 75% inactivation and loss of ADP activation concomitant with incorporation of about 1 mol of reagent/mol of average enzyme subunit (Huang, Y.-C., Bailey, J. M., and Colman, R. F. (1986) J. Biol. Chem. 251, 14100-14107). Complete protection against the functional changes is provided by ADP + Mn2+, and reagent incorporation is decreased to about 0.5 mol/mol of average enzyme subunit. We have now identified the critical modified peptide by comparison of the peptides labeled by 2-BDB-TADP at pH 6.8 in the absence and presence of ADP + Mn2+. After removal of excess reagent, modified enzyme was treated with [3H]NaBH4 to reduce the keto groups of the reagent and introduce a radioactive tracer into the reagent which is covalently linked to the protein. Following carboxymethylation and digestion with trypsin, the specific modified peptide was isolated using two successive high performance liquid chromatography steps: 1) 0.1% trifluoroacetic acid with an acetonitrile gradient; and 2) 20 mM ammonium acetate, pH 5.8, with an acetonitrile gradient. Gas phase sequencing gave the modified peptide Leu-Gly-Asp-Gly-Leu-Phe-Leu-Gln in which aspartic acid is the target of 2-BDB-TADP. Isolation of the corresponding tryptic peptide from unmodified enzyme yielded the sequence Leu-Gly-Asp-Gly-Leu-Phe-Leu-Gln-CmCys-CmCys-Lys. Isocitrate dehydrogenase is composed of three distinct subunits (alpha, beta, and gamma), separable by chromatofocusing in urea and identified by analytical gel isoelectric focusing. The evidence indicates that the specific peptide labeled by 2-BDB-TADP, which is at or near the ADP site, can be derived from the gamma subunit.
...
PMID:Aspartyl peptide labeled by 2-(4-bromo-2,3-dioxobutylthio)adenosine 5'-diphosphate in the allosteric ADP site of pig heart NAD+-dependent isocitrate dehydrogenase. 274 37

2-(4-Bromo-2,3-dioxobutylthio)-1,N(6)-ethenoadenosine 2',5'-bisphosphate (2-BDB-T epsilon A-2',5'-DP) is an affinity label for the coenzyme-binding site of pig heart NADP+-dependent isocitrate dehydrogenase. Specific reaction occurs at the coenzyme site with an incorporation of 0.5 mol of reagent/mol of enzyme subunit (i.e. modification of only one subunit of the dimeric enzyme) (Bailey, J.M., and Colman, R.F. (1985) Biochemistry 24, 5367-5377). Modified enzyme, prepared by incubating 1 mg/ml isocitrate dehydrogenase with 75 microM 2-BDB-T epsilon A-2',5'-DP in the absence and presence of substrate or coenzyme, was reduced with NaBH4, carboxymethylated, and digested with trypsin. Nucleotidyl peptides were isolated by chromatography on DEAE-cellulose, followed by treatment with acid phosphatase (to decrease the negative charge by removing the phosphate groups from covalently bound reagent) and rechromatography on the same DEAE-cellulose column. The isolated peptides were characterized by amino acid analysis, dansylation, and gas-phase sequencing. A single triskaidekapeptide corresponding to modification of the coenzyme site by 2-BDB-T epsilon A-2',5'-DP was identified as: Asp-Leu-Ala-Gly-X-Ile-His-Gly-Leu-Ser-Asn-Val-Lys. Additional evidence indicated that X is a glutamate residue derivatized by 2-BDB-T epsilon A-2',5'-DP.
...
PMID:Isolation of the glutamyl peptide labeled by the nucleotide analogue 2-(4-bromo-2,3-dioxobutylthio)-1,N(6)-ethenoadenosine 2',5'-biphosphate in the active site of NADP+-specific isocitrate dehydrogenase. 288 70

No glycolate oxidase activity could be detected by manometric, isotopic, or spectrophotometric techniques in cell extracts from 5 strains of algae grown in the light with CO(2). However, NADH:glyoxylate reductase, phosphoglycolate phosphatase and isocitrate dehydrogenase were detected in the cell extracts. The serine formed by Chlorella or Chlamydomonas after 12 seconds of photosynthetic (14)CO(2) fixation contained 70 to 80% of its (14)C in the carboxyl carbon. This distribution of label in serine was similar to that in phosphoglycerate from the same experiment. Thus, in algae serine is probably formed directly from phosphoglycerate. These results differ from those of higher plants which form uniformly labeled serine from glycolate in short time periods when phosphoglycerate is still carboxyl labeled. In glycolate formed by algae in 5 and 10 seconds of (14)CO(2) fixation, C(2) was at least twice as radioactive as C(1). A similar skewed labeling in C(2) and C(3) of 3-phosphoglycerate and serine suggests a common precursor for glycolate and 3-phosphoglycerate. Glycine formed by the algae, however, from the same experiments was uniformly labeled. Manganese deficient Chlorella incorporated only 2% of the total (14)CO(2) fixed in 10 minutes into glycolate, while in normal Chlorella 30% of the total (14)C was found in glycolate. Manganese deficient Chlorella also accumulated more (14)C in glycine and serine.Glycolate excretion by Chlorella was maximal in 10 mm bicarbonate and occurred only in the light, and was not influenced by the addition of glycolate. No time dependent uptake of significant amounts of either glycolate or phosphoglycolate was observed. When small amounts of glycolate-2-(14)C were fed to Chlorella or Scenedesmus, only 2 to 3% was metabolized after 30 to 60 minutes. The algae were not capable of significant glycolate metabolism as is the higher plant. The failure to detect glycolate oxidase, the low level glycolate-(14)C metabolism, and the formation of serine from phosphoglycerate rather than from glycolate are consistent with the concept of an incomplete glycolate pathway in algae.
...
PMID:Glycolate pathway in algae. 604 96

ADP-L-glycero-D-mannoheptose 6-epimerase is required for lipopolysaccharide inner core biosynthesis in several genera of Gram-negative bacteria. The enzyme contains both fingerprint sequences Gly-X-Gly-X-X-Gly and Gly-X-X-Gly-X-X-Gly near its N terminus, which is indicative of an ADP binding fold. Previous studies of this ADP-l-glycero-D-mannoheptose 6-epimerase (ADP-hep 6-epimerase) were consistent with an NAD(+) cofactor. However, the crystal structure of this ADP-hep 6-epimerase showed bound NADP (Deacon, A. M., Ni, Y. S., Coleman, W. G., Jr., and Ealick, S. E. (2000) Structure 5, 453-462). In present studies, apo-ADP-hep 6-epimerase was reconstituted with NAD(+), NADP(+), and FAD. In this report we provide data that shows NAD(+) and NADP(+) both restored enzymatic activity, but FAD could not. Furthermore, ADP-hep 6-epimerase exhibited a preference for binding of NADP(+) over NAD(+). The K(d) value for NADP(+) was 26 microm whereas that for NAD(+) was 45 microm. Ultraviolet circular dichroism spectra showed that apo-ADP-hep 6-epimerase reconstituted with NADP(+) had more secondary structure than apo-ADP-hep 6-epimerase reconstituted with NAD(+). Perchloric acid extracts of the purified enzyme were assayed with NAD(+)-specific alcohol dehydrogenase and NADP(+)-specific isocitric dehydrogenase. A sample of the same perchloric acid extract was analyzed in chromatographic studies, which demonstrated that ADP-hep 6-epimerase binds NADP(+) in vivo. A structural comparison of ADP-hep 6-epimerase with UDP-galactose 4-epimerase, which utilizes an NAD(+) cofactor, has identified the regions of ADP-hep 6-epimerase, which defines its specificity for NADP(+).
...
PMID:Evidence that NADP+ is the physiological cofactor of ADP-L-glycero-D-mannoheptose 6-epimerase. 1131 58

Three Gram-positive bacterial strains, 7-3, 255-15 and 190-11, previously isolated from Siberian permafrost, were characterized and taxonomically classified. These microorganisms are rod-shaped, facultative aerobic, motile with peritrichous flagella and their growth ranges are from -2.5 to 40 degrees C. The chemotaxonomic markers indicated that the three strains belong to the genus Exiguobacterium. Their peptidoglycan type was A3alpha L-Lys-Gly. The predominant menaquinone detected in all three strains was MK7. The polar lipids present were phosphatidyl-glycerol, diphosphatidyl-glycerol and phosphatidyl-ethanolamine. The major fatty acids were iso-C13:0, anteiso-C13:0, iso-C15:0, C16:0 and iso-C17:0. Phylogenetic analysis based on 16S rRNA and six diverse genes, gyrB (gyrase subunit B), rpoB (DNA-directed RNA polymerase beta subunit), recA (homologous recombination), csp (cold shock protein), hsp70 (ClassI-heat shock protein-chaperonin) and citC (isocitrate dehydrogenase), indicated that the strains were closely related to Exiguobacterium undae (DSM 14481(T)) and Exiguobacterium antarcticum (DSM 14480(T)). On the basis of the phenotypic characteristics, phylogenetic data and DNA-DNA reassociation data, strain 190-11 was classified as E. undae, while the other two isolates, 7-3 and 255-15, comprise a novel species, for which the name Exiguobacterium sibiricum sp. nov. is proposed.
...
PMID:Characterization of Exiguobacterium isolates from the Siberian permafrost. Description of Exiguobacterium sibiricum sp. nov. 1648 12

The enzymatic capacity for metabolism of poly-(beta)-hydroxybutyrate (PHB) has been examined in nitrogen-fixing symbioses of soybean (Glycine max L.) plants, which may accumulate substantial amounts of PHB, and chickpea (Cicer arietinum L.) plants, which contain little or no PHB. In the free-living state, both Bradyrhizobium japonicum CB 1809 and Rhizobium sp. (Cicer) CC 1192, which form nodules on soybean and chickpea plants, respectively, produced substantial amounts of PHB. To obtain information on why chickpea bacteroids do not accumulate PHB, the specific activities of enzymes of PHB metabolism (3-ketothiolase, acetoacetyl-coenzyme A reductase, PHB depolymerase, and 3-hydroxybutyrate dehydrogenase), the tricarboxylic acid cycle (malate dehydrogenase, citrate synthase, and isocitrate dehydrogenase), and related reactions (malic enzyme, pyruvate dehydrogenase, and glutamate:2-oxoglutarate transaminase) were compared in extracts from chickpea and soybean bacteroids and the respective free-living bacteria. Significant differences were noted between soybean and chickpea bacteroids and between the bacteroid and free-living forms of Rhizobium sp. (Cicer) CC 1192, with respect to the capacity for some of these reactions. It is suggested that a greater potential for oxidizing malate to oxaloacetate in chickpea bacteroids may be a factor that favors the utilization of acetyl-coenzyme A in the tricarboxylic acid cycle over PHB synthesis.
...
PMID:Enzymes of Poly-(beta)-Hydroxybutyrate Metabolism in Soybean and Chickpea Bacteroids. 1653 45

Soybean Glycine max. L. Merr. nodule senescence was studied using the loss of acetylene reduction by intact tap root nodules as its indication. Tap root nodules from two varieties (Calland and Beeson) of field-grown soybeans were used. The specific activities of nitrogenase (micromoles/minute gram fresh weight of nodules) as measured by the acetylene reduction assay decreased abruptly between 58 to 65 and 68 to 75 days after planting the Beeson and Calland soybeans, respectively. Major changes were not detected in dry weight, total nitrogen, and leghemoglobin levels during the period when in vivo nitrogenase activity declined. Ammonium levels in the cytosol of nodules and poly-beta-hydroxybutyrate increased moderately just prior to or coincidental with the loss of nitrogenase activity. Neither enzymes that have been postulated to be involved in ammonium assimilation nor NADP(+)-specific isocitrate dehydrogenase exhibited any large changes in specific activities during the initial period when nitrogenase activity declined.
...
PMID:Studies on soybean nodule senescence. 1665 38

The influence of low temperature on soybean (Glycine max [L.] Merr. cv. Wells) energy transduction via mitochondrial respiration and dehydrogenases was investigated in this study during imbibition and germination. Mitochondria were isolated from embryonic axes of seeds treated at 10 and 23 C (control) by submergence in H(2)O for 6 hours and maintenance for an additional 42 hours in a moist environment. Arrhenius plots of initial respiration rates revealed that those from cold-treated axes had respiratory control (RC) ratios of near 1.0 above an inflection in the plot at 8 C. Arrhenius plots of control axes mitochondrial respiration showed RC ratios of 2.8 above and 5.0 below an inflection temperature of 12.5 C. Energies of activation for mitochondrial respiration between 20 and 30 C for the cold and control treatments were 7.8 and 15.6 kcal/mole, respectively. These data indicate possible differences in mitochondrial membranes, degree of mitochondrial integrity, and mitochondrial enzyme complement between the two treatments.Glutamate dehydrogenase (GDH), malate dehydrogenase (MDH), alcohol dehydrogenase (ADH), glucose-6-phosphate dehydrogenase (G6P-DH), and NADP-isocitrate dehydrogenase (NADP-ICDH) were assayed from whole seeds and axes (after germination) during the 48 hours of temperature treatments. Activity of these dehydrogenases decreased during the first 6 hours with the exception of MDH. After germination at 23 C (48 hours) all five dehydrogenases increased in activity. Arrhenius plots of cotyledon dehydrogenase activities indicated that one inflection temperature between 6 and 18 C was present for each enzyme assayed. Differences were seen in Arrhenius plots of axes dehydrogenase activities with the two temperature treatments in the cases of GDH and MDH from mitochondrial pellets and with differences in enzyme extraction media. These data suggest that the temperature treatments yield differences in mitochondrial enzyme complement. There were no detectable inflection temperatures for the activities of G6P-DH and ADH extracted from axes. Arrhenius plots of NADP-ICDH activity indicated extreme cold sensitivity. The slopes of the plots for axes NADP-ICDH were very similar to those for mitochondrial respiration (23 C treatment) suggesting that this enzyme may limit mitochondrial respiration at low temperature in soybean tissues grown at moderate temperatures.
...
PMID:Low Temperature Effects on Soybean (Glycine max [L.] Merr. cv. Wells) Mitochondrial Respiration and Several Dehydrogenases during Imbibition and Germination. 1666 Jan 71

Changes in levels of isocitrate lyase, malate synthase, and catalase have been investigated during germination of flax (Linum usitatissimum L.) in the presence and absence of itaconate. Germination was accompanied by a rapid increase in these enzymes during the first 3 days. The presence of 38 millimolar itaconate inhibited the incidence of seed germination and the growth of embryo axes as well as the appearance of isocitrate lyase but did not alter the levels of malate synthase, catalase, or NADP(+)-isocitrate dehydrogenase. The specific activity for the latter enzyme was constant throughout germination. Oxalate or succinate, each at 38 millimolar, had no effect upon germination of flax seeds. Itaconate did not inhibit the activities of malate synthase, catalase, or NADP(+)-isocitrate dehydrogenase in vitro but was a potent noncompetitive inhibitor of isocitrate lyase (K(i):17 micromolar at 30 C, pH 7.6). Itaconate (at 38 millimolar) did not alter the appearance of malate synthase but reduced the incidence of germination, onset of germination, and growth of the embryo axis as well as the specific activity of isocitrate lyase in seedlings of Zea mays, Vigna glabra, Glycine hispida, Vigna sinensis, Trigonella foenumgraecum, Lens culinaris, and Medicago sativa. The incidence and onset of germination of wheat seeds were unaltered by the same concentration of itaconate but seedlings did not contain isocitrate lyase or malate synthase. The data suggest that itaconate may be isocitrate lyase-directed in inhibiting the germination of fatty seeds.
...
PMID:Enzyme Profiles in Seedling Development and the Effect of Itaconate, an Isocitrate Lyase-directed Reagent. 1666 Sep 38

During the period of most active leaf expansion, the foliar dark respiration rate of soybeans (Glycine max cv Williams), grown for 2 weeks in 1000 microliters CO(2) per liter air, was 1.45 milligrams CO(2) evolved per hour leaf density thickness, and this was twice the rate displayed by leaves of control plants (350 microliters CO(2) per liter air). There was a higher foliar nonstructural carbohydrate level (e.g. sucrose and starch) in the CO(2) enriched compared with CO(2) normal plants. For example, leaves of enriched plants displayed levels of nonstructural carbohydrate equivalent to 174 milligrams glucose per gram dry weight compared to the 84 milligrams glucose per gram dry weight found in control plant leaves. As the leaves of CO(2) enriched plants approached full expansion, both the foliar respiration rate and carbohydrate content of the CO(2) enriched leaves decreased until they were equivalent with those same parameters in the leaves of control plants. A strong positive correlation between respiration rate and carbohydrate content was seen in high CO(2) adapted plants, but not in the control plants.Mitochondria, isolated simultaneously from the leaves of CO(2) enriched and control plants, showed no difference in NADH or malate-glutamate dependent O(2) uptake, and there were no observed differences in the specific activities of NAD(+) linked isocitrate dehydrogenase and cytochrome c oxidase. Since the mitochondrial O(2) uptake and total enzyme activities were not greater in young enriched leaves, the increase in leaf respiration rate was not caused by metabolic adaptations in the leaf mitochondria as a response to long term CO(2) enrichment. It was concluded, that the higher respiration rate in the enriched plant's foliage was attributable, in part, to a higher carbohydrate status.
...
PMID:Effects of CO(2) Enrichment and Carbohydrate Content on the Dark Respiration of Soybeans. 1666 73


1 2 Next >>

---