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:1.12.7.2 (hydrogenase)
3,522 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Di-myo-inositol-1,1(prm1)-phosphate (DIP) is present at a significant concentration ((symbl)160 nmol/mg of protein) in the cytoplasm of the hyperthermophilic bacterium Thermotoga maritima. The concentration of DIP was independent of the pH of the growth medium or the cell growth phase but increased with increasing concentrations of NaCl in the growth medium, reaching a maximum ((symbl)450 nmol/mg of protein) at 0.4 to 0.6 M NaCl. A large-scale purification procedure for DIP which yields approximately 18 g of DIP per kg of cells (wet weight) is described. Purified DIP was stable at 90(deg)C for at least 5 h. The presence of DIP (50 mM) did not increase the stability at 90(deg)C of pure forms of the hydrogenase or pyruvate ferredoxin oxidoreductase of T. maritima, suggesting that DIP is not a general thermoprotectant.
...
PMID:Characterization of Di-myo-Inositol-1,1(prm1)-Phosphate in the Hyperthermophilic Bacterium Thermotoga maritima. 1653 98

Fukuyama, T. (University of Washington, Seattle), and E. J. Ordal. Induced biosynthesis of formic hydrogenlyase in iron-deficient cells of Escherichia coli. J. Bacteriol. 90:673-680. 1965.-Escherichia coli cells were grown aerobically on a lactate-mineral salts medium from which iron had been removed by extraction with 8-hydroxyquinoline and chloroform. These cells carried out induced biosynthesis of formic hydrogenlyase in a reaction mixture containing glucose, formate, and phosphate without the addition of amino acids, providing adequate amounts of iron salts were present. In the absence of iron, glucose was fermented and acids were produced, but no formic hydrogenlyase developed. When iron-deficient E. coli cells were repeatedly washed, the property of carrying out induced biosynthesis of formic hydrogenlyase with glucose, formate, phosphate, and iron was lost, but was restored on addition of acid-hydrolyzed casein to the reaction mixture. An energy source (provided as glucose) was necessary for enzyme production. Iron-deficient cells were devoid of hydrogenase and formic hydrogenlyase but showed formic dehydrogenase activity when adequate amounts of selenium and molybdenum were present in the growth medium. Hydrogenase was consistently absent in iron-deficient cells but appeared concomitantly with formic hydrogenlyase during induced biosynthesis of the latter in iron-deficient cells of E. coli.
...
PMID:Induced Biosynthesis of Formic Hydrogenlyase in Iron-Deficient Cells of Escherichia coli. 1656 66

A spinach (Spinacia oleracia var. America) chloroplast particle fortified with ferredoxin, fructose-1,6-bisphosphate, or ribose-5-phosphate and NADP has been shown to generate NADPH by the oxidation of glyceraldehyde-3 phosphate to glycerate-3-phosphate (PGA) and to reduce ferredoxin with the NADPH. The resulting reduced ferredoxin can reduce O(2) to H(2)O(2), nitrite to ammonia, or protons to H(2). Hydrogen production was the result of adding hydrogenase from Chlamydomonas reinhardii to the chloroplast preparation. The predicted stoichiometry of 1 PGA:1 O(2) in the absence of and 2 PGA:1 O(2) in the presence of catalase was observed indicating H(2)O(2) as the end product of O(2) reduction. The predicted stoichiometry of 3 PGA:1 nitrite:1 ammonia was also observed. A scheme is presented to account for a sustained generation of NADP and ATP necessary for the dissimilation of starch in the darkened chloroplast. The unifying term chloroplast respiration is introduced to account for those reactions in which reduced ferredoxin interacts with physiological acceptors other than NADP or nitrite, hydrogen, or O(2) respiration when nitrite, protons, or O(2) is the ultimate electron acceptor.
...
PMID:Chloroplast Respiration : A MEANS OF SUPPLYING OXIDIZED PYRIDINE NUCLEOTIDE FOR DARK CHLOROPLASTIC METABOLISM. 1666 26

Isolated intact chloroplasts of Chlamydomonas reinhardii were found to catalyze photoreduction of CO(2) in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea when adapted under an atmosphere of H(2) demonstrating the association of a hydrogenase and anaerobic adaptation system with these plastids. The specific activity of photoreduction was approximately one third that detected in cells and protoplasts. Photoreduction was found to have a lower osmoticum optimum relative to aerobically maintained chloroplasts (50 millimolar versus 120 millimolar mannitol). 3-Phosphoglycerate (3-PGA) stimulated photoreduction up to a peak at 0.25 millimolar beyond which inhibition was observed. In the absence of 3-PGA, inorganic phosphate had no effect on photoreduction but in the presence of 3-PGA, inorganic phosphate also stimulated the reaction. Carbonyl cyanide-p-trifluoromethoxyphenylhydrazone and 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone inhibited photoreduction but inhibition by the former could be partially overcome by exogenously added ATP. The intact plastid can also catalyze photoevolution of H(2) while lysed chloroplast extracts catalyzed the reduction of methyl viologen by H(2). Both reactions occurred at rates approximately one-third of those found in cells. The oxyhydrogen reaction in the presence or absence of CO(2) was not detected.
...
PMID:Hydrogenase-Mediated Activities in Isolated Chloroplasts of Chlamydomonas reinhardii. 1666 26

A correlation between the rate of ATP synthesis by F0F1 ATP-synthase and formate oxidation by formate hydrogen lyase (FHL) has been established in inverted membrane vesicles of Escherichia coli JW 136 mutant with double deletions (delta hya/ delta hyb) of hydrogenase 1 and 2 grown anaerobically on glucose in the absence of external electron acceptors (pH 6.5). ATP synthesis was suppressed by H+ -ATPase inhibitors N,N'-dicyclohexylcarbodiimide (DCCD) and sodium azide as well as by the protonophore carbonyl cyanide-m-chlorophenyhydrazone (CCCP). Copper ions inhibited formate-dependent hydrogenase and ATP-synthase activities but did not affect the ATPase activity of vesicles. The maximal rate of ATP synthesis (0.83 microM/min x mg protein) stimulated by K+ ions was determined when sodium formate, ADP and inorganic phosphate were applied simultaneously. The results confirm the assumption about the dual role of hydrogenase 3, formate hydrogen lyase subunit, which is able to couple the reduction of protons to H2 and their translocation through a membrane with chemiosmotic synthesis of ATP.
...
PMID:[Energy transformation coupled to formate oxidation during anaerobic fermentation]. 1680 45

Albumin induces oxidative stress and cytokine production in proximal tubular cells (PTECs). Albumin-bound fatty acids (FAs) enhance tubulopathic effects of albumin in vivo. We proposed that FA aggravation of albumin-induced oxidative stress in PTECs might be involved. We hypothesized that mitochondria could be a source of such stress. Using a fluorescent probe, we compared reactive oxygen species (ROS) production after exposure of PTECs to bovine serum albumin (BSA) alone or loaded with oleic acid (OA-BSA) (3-30 g/l for 2 h). There was no difference in cellular albumin uptake, but OA-BSA dose-dependently induced more ROS than BSA alone (P<0.001). OA-BSA-induced ROS was significantly alleviated by mitochondrial inhibition, but not by inhibitors of nicotinamide adenine dinucleotide phosphate hydrogenase (NADPH) oxidase, xanthine oxidase, or nitric oxide synthase. Gene expression analysis showed that neither the NADPH oxidase component p22phox nor xanthine oxidase was induced by BSA or OA-BSA. OA-BSA, in contrast to BSA, failed to induce mitochondrial manganese superoxide dismutase 2 (SOD2) expression. OA-BSA showed a greater capacity than BSA to downregulate heme oxygenase-1 mRNA expression and accentuate inflammatory cytokine mRNA and protein. Supplementation of SOD activity with EUK-8 reduced ROS, and interleukin-6 protein expression was suppressed by both mitochondrial inhibition and SOD augmentation. Thus, in PTECs, FAs accentuate albumin-induced oxidative stress and inflammatory cytokine expression via increased mitochondrial ROS, while frustrating protective antioxidant responses.
...
PMID:Albumin-bound fatty acids induce mitochondrial oxidant stress and impair antioxidant responses in proximal tubular cells. 1683 28

Hydrogenases catalyze the reversible oxidation of dihydrogen. Catalysis occurs at bimetallic active sites that contain either nickel and iron or only iron and the nature of these active sites forms the basis of categorizing the enzymes into three classes, the [NiFe]-hydrogenases, the [FeFe]-hydrogenases and the iron sulfur cluster-free [Fe]-hydrogenases. The [NiFe]-hydrogenases and the [FeFe]-hydrogenases are unrelated at the amino acid sequence level but the active sites share the unusual feature of having diatomic ligands associated with the Fe atoms in the these enzymes. Combined structural and spectroscopic studies of [NiFe]-hydrogenases identified these diatomic ligands as CN- and CO groups. Major advances in our understanding of the biosynthesis of these ligands have been achieved primarily through the study of the membrane-associated [NiFe]-hydrogenases of Escherichia coli. A complex biosynthetic machinery is involved in synthesis and attachment of these ligands to the iron atom, insertion of the Fe(CN)2CO group into the apo-hydrogenase, introduction of the nickel atom into the pre-formed active site and ensuring that the holoenzyme is correctly folded prior to delivery to the membrane. Although much remains to be uncovered regarding each of the individual biochemical steps on the pathway to synthesis of a fully functional enzyme, our understanding of the initial steps in CN- synthesis have revealed that it is generated from carbamoyl phosphate. What is becoming increasingly clear is that the metabolic origins of the carbonyl group may be different.
...
PMID:Maturation of [NiFe]-hydrogenases in Escherichia coli. 1721 1

The hydrogenase maturation protein HypE serves an essential function in the biosynthesis of the nitrile group, which is subsequently coordinated to Fe as CN(-) ligands in [Ni-Fe] hydrogenase. Here, we present the crystal structures of HypE from Desulfovibrio vulgaris Hildenborough in the presence and in the absence of ATP at a resolution of 2.0 A and 2.6 A, respectively. Comparison of the apo structure with the ATP-bound structure reveals that binding ATP causes an induced-fit movement of the N-terminal portion, but does not entail an overall structural change. The residue Cys341 at the C terminus, whose thiol group is supposed to be carbamoylated before the nitrile group synthesis, is completely buried within the protein and is located in the vicinity of the gamma-phosphate group of the bound ATP. This suggests that the catalytic reaction occurs in this configuration but that a conformational change is required for the carbamoylation of Cys341. A glutamate residue is found close to the thiol group as well, which is suggestive of deprotonation of the carbamoyl group at the beginning of the reactions.
...
PMID:Crystal structures of hydrogenase maturation protein HypE in the Apo and ATP-bound forms. 1770 67

Thiamin monophosphate kinase (ThiL) catalyzes the ATP-dependent phosphorylation of thiamin monophosphate (TMP) to form thiamin pyrophosphate (TPP), the active form of vitamin B 1. ThiL is a member of a small ATP binding superfamily that also includes the purine biosynthetic enzymes, PurM and PurL, NiFe hydrogenase maturation protein, HypE, and selenophosphate synthase, SelD. The latter four enzymes are believed to utilize phosphorylated intermediates during catalysis. To understand the mechanism of ThiL and its relationship to the other superfamily members, we determined the structure of Aquifex aeolicus ThiL (AaThiL) with nonhydrolyzable AMP-PCP and TMP, and also with the products of the reaction, ADP and TPP. The results suggest that AaThiL utilizes a direct, inline transfer of the gamma-phosphate of ATP to TMP rather than a phosphorylated enzyme intermediate. The structure of ThiL is compared to those of PurM, PurL, and HypE, and the ATP binding site is compared to that of PurL, for which nucleotide complexes are available.
...
PMID:Structural studies of thiamin monophosphate kinase in complex with substrates and products. 1831 27

Bradyrhizobium japonicum is a facultative chemoautotroph capable of utilizing hydrogen gas as an electron donor in a respiratory chain terminated by oxygen to provide energy for cellular processes and carbon dioxide assimilation via a reductive pentose phosphate pathway. A transcriptomic analysis of B. japonicum cultured chemoautotrophically identified 1,485 transcripts, representing 17.5% of the genome, as differentially expressed when compared to heterotrophic cultures. Genetic determinants required for hydrogen utilization and carbon fixation, including the uptake hydrogenase system and components of the Calvin-Benson-Bassham cycle, were strongly induced in chemoautotrophically cultured cells. A putative isocitrate lyase (aceA; blr2455) was among the most strongly upregulated genes, suggesting a role for the glyoxylate cycle during chemoautotrophic growth. Addition of arabinose to chemoautotrophic cultures of B. japonicum did not significantly alter transcript profiles. Furthermore, a subset of nitrogen fixation genes was moderately induced during chemoautotrophic growth. In order to specifically address the role of isocitrate lyase and nitrogenase in chemoautotrophic growth, we cultured aceA, nifD, and nifH mutants under chemoautotrophic conditions. Growth of each mutant was similar to that of the wild type, indicating that the glyoxylate bypass and nitrogenase activity are not essential components of chemoautotrophy in B. japonicum.
...
PMID:Whole-genome transcriptional profiling of Bradyrhizobium japonicum during chemoautotrophic growth. 1868 88


<< Previous 1 2 3 4 5 6 7 8 Next >>

---