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Query: UMLS:C0348321 (Haemophilus)
 15,372 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Six strains of Haemophilus species, pathogenic to chickens, required 1-0 to 1-5% (w/v) NaCl for optimum growth. The requirement was for Na+ rather than NaCl. A sodium salt buffer influenced the optimum NaCl requirement and enhanced growth. Each strain required a different concentration of NADH for an optimum rate of growth.
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PMID:The effect of sodium chloride and NADH on the growth of six strains of haemophilus species pathogenic to chickens. 19 32

Haemophilus parasuis, grown under conditions of high aeration, was found to lack a tricarboxylic acid cycle but to possess phosphoenolpyruvate carboxylase and a reductive pathway leading to the production of succinate. Such organisms contained approximately equal quantities of b-, c-, and d-type cytochromes and excreted acetate. When the oxygen supply for growth was either reduced or eliminated, the specific activities of phosphoenolpyruvate carboxylase, malate dehydrogenase, fumarase, fumarate reductase, and NADH: fumarate oxidoreductase were increased substantially, and the acid products were succinate, acetate, and formate. Organisms grown under the latter conditions also contained increased quantities of b- and c-type cytochromes, some of which were low-potential cytochromes. These low-potential cytochromes were reduced by NADH and oxidized by fumarate, and hence, appeared to be components of NADH: furmarate oxidoreductase. Our results indicate that in H. parasuis, growing aerobically in medium containing glucose, the sole function of the reductive pathway is to provide intermediates for biosynthetic processes, and oxygen is the preferred electron acceptor. As the supply of oxygen is reduced or eliminated, the reductive pathway becomes more involved in NAD+ recycling and fumarate becomes the acceptor. In effect, irrespective of the oxygen supply, the growth of H. parasuis is absolutely dependent upon the presence of an electron transport system.
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PMID:Effect of oxygen supply during growth on the production of cytochromes, enzymes, and acid end products by Haemophilus parasuis. 146 68

Haemophilus influenzae D(-)-lactate dehydrogenase (D(-)-lactate:NAD oxidoreductase; EC 1.1.1.28) was purified to electrophoretic homogeneity using salt fractionation, hydrophobic and dye affinity chromatography. The enzyme was purified 2100-fold with a 14% recovery and a final specific activity of 300 units/mg protein. The enzyme was demonstrated to be a tetramer of Mr 135,000. The enzyme catalyzed the reduction of pyruvate to give exclusively D(-)-lactate using NADH as coenzyme. The reaction catalyzed was essentially unidirectional, with the oxidation of D-lactate in the presence of NAD proceeding at less than 0.2% the rate of pyruvate reduction. Kinetic parameters for the reduction of pyruvate were determined for NADH and four structural analogs of the coenzyme. Coenzyme-competitive inhibition by adenosine derivatives indicated the presence of regions in the coenzyme binding site interacting with the adenosine and pyrophosphate moieties of the coenzyme. The purified enzyme was sensitive to oxidation and was effectively inactivated by sulfhydryl reagents. Conversion of D-lactate to pyruvate catalyzed by a membrane-bound D-lactate oxidase was demonstrated in cell-free extracts of H. influenzae.
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PMID:Purification and characterization of Haemophilus influenzae D-lactate dehydrogenase. 230 73

A series of N-alkylmaleimides varying in chain length from N-ethyl up to and including N-heptyl, was shown to effectively inactivate Haemophilus influenzae D-lactate dehydrogenase at pH 7.0 and 25 degrees C in processes proposed to involve covalent modification of cysteine residues. The inactivation proceeded through an initial reversible binding of maleimides facilitated by nonpolar interactions with a hydrophobic region of the enzyme. Subsequent irreversible inactivation of the enzyme indicated the modification of a fast-reacting group leading to approx. 80% loss of enzyme activity followed by a second slower-reacting modification process. At saturating concentrations of maleimides, the second inactivation process exhibited a common pseudo-first-order rate constant of 0.6 min-1. The initial reversible binding of N-alkylmaleimides resulted in inhibition of the enzyme that was competitive with respect to NADH. Positive chain length effects were observed in the second-order rate constants for inactivation and in the 6-fold better binding of N-heptylmaleimide as compared to that for N-ethylmaleimide. It is suggested that the nonpolar interactions stabilizing the 1,4-dihydronicotinamide moiety of the reduced coenzyme also facilitate the initial binding of N-alkylmaleimides.
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PMID:Nonpolar interactions in the maleimide inactivation of Haemophilus influenzae D-lactate dehydrogenase. 237 5

Haemophilus influenzae malate dehydrogenase [S)-malate: NAD+ oxidoreductase EC 1.1.1.37) was purified 109-fold with a 26% recovery through a four-step procedure involving salt fractionation, hydrophobic and dye affinity chromatography. The purified enzyme was demonstrated to be a dimer of Mr 61,000. Initial velocity studies of all four substrates in the forward and reverse reactions indicated a sequential mechanism for the enzyme. Product and dead-end inhibition studies were consistent with an ordered bi-bi mechanism in which NAD is the first substrate bound to the enzyme and NADH, the second product released. Several analogs of NAD structurally altered in either the pyridine or purine moiety were observed to function as coenzymes in the reaction catalyzed by the purified malate dehydrogenase. Alterations in the purine portion of the dinucleotides had a more pronounced effect on the kinetic parameters observed in malate oxidation. The enzyme was inactivated by incubation with diethylpyrocarbonate, whereas no inactivation was observed with sulfhydryl reagents.
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PMID:Kinetic studies of Haemophilus influenzae malate dehydrogenase. 326 Jan 11

Spectral analyses with subcellular fractions derived from Haemophilus parasuis demonstrated that this organism could synthesize membrane-bound and soluble CO- and NO-binding c-type cytochromes in addition to the membrane-bound cytochromes d, a1, b, and c; cytochromes d, a1, and o were identified as potential oxidases. The membrane-bound and soluble CO- and NO-binding cytochromes c were not spectrally variant cytochromes c, and the redox properties of the soluble cytochrome (reducible by NADH but not by succinate or ascorbate plus N,N,N',N'-tetramethyl-p-phenylenediamine) suggested that it, at least, was a low-potential cytochrome; up to 68% of the soluble cytochrome c could be released from the organisms by osmotic-shock treatment, demonstrating its extracytoplasmic location. The cytochrome content of H. parasuis was influenced by both the composition of the growth medium and the phase of growth; it is suggested that the bacterial concentration and growth rate, and therefore the availability of oxygen, regulated cytochrome synthesis.
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PMID:The cytochrome complement of Haemophilus parasuis. 648 1

We previously cloned and sequenced nqr operon encoding the Na+-translocating NADH-quinone reductase (NQR) from the marine bacterium Vibrio alginolyticus. A gene cluster very similar to nqr operon was found to exist in the genome of Haemophilus influenzae Rd. We examined the membrane fraction from H. influenzae, and the respiratory chain of H. influenzae was found to contain a Na+-dependent NQR that is essentially identical to those found in the marine V. alginolyticus. These results indicate that quite similar to the salt-loving marine bacteria, the blood-loving H. influenzae has a redox-driven Na+ pump and utilizes Na+ circulation for energy coupling.
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PMID:Existence of Na+-translocating NADH-quinone reductase in Haemophilus influenzae. 860 49

The region of the genome of Mycoplasma capricolum upstream of the portion encompassing the genes for Enzymes I and IIAglc of the phosphoenolpyruvate:sugar phosphotransferase system (PTS) was cloned and sequenced. Examination of the sequence revealed open reading frames corresponding to numerous genes involved with the oxidation of pyruvate. The deduced gene organization is naox (encoding NADH oxidase)-lplA (encoding lipoate-protein ligase)-odpA (encoding pyruvate dehydrogenase EI alpha)-odpB (encoding pyruvate dehydrogenase EI beta)-odp2(encoding pyruvate dehydrogenase EII)-dldH (encoding dihydrolipoamide dehydrogenase)-pta (encoding phosphotransacetylase)-ack (encoding acetate kinase)-orfA (an unknown open reading frame)-kdtB-ptsI-crr. Analysis of the DNA sequence suggests that the naox and lplA genes are part of a single operon, odpA and odpB constitute an additional operon, odp2 and dldH a third operon, and pta and ack an additional transcription unit. Phylogenetic analyses of the protein products of the odpA and odpB genes indicate that they are most similar to the corresponding proteins from Mycoplasma genitalium, Acholeplasma laidlawii, and Gram-positive organisms. The product of the odp2 gene contains a single lipoyl domain, as is the case with the corresponding proteins from M. genitalium and numerous other organisms. An evolutionary tree places the M. capricolum odp2 gene product in close relationship to the corresponding proteins from A. laidlawii and M.genitalium. The dldH gene encodes an unusual form of dihydrolipoamide dehydrogenase that contains an aminoterminal extension corresponding to a lipoyl domain, a property shared by the corresponding proteins from Alcaligenes eutrophus and Clostridium magnum. Aside from that feature, the protein is related phylogenetically to the corresponding proteins from A. laidlawii and M. genitalium. The phosphotransacetylase from M. capricolum is related most closely to the corresponding protein from M. genitalium and is distinguished easily from the enzymes from Escherichia coli and Haemophilus influenzae by the absence of the characteristic amino-terminal extension. The acetate kinase from M. capricolum is related evolutionarily to the homologous enzyme from M. genitalium. Map position comparisons of genes encoding proteins involved with pyruvate metabolism show that, whereas all the genes are clustered in M. capricolum, they are scattered in M. genitalium.
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PMID:Sequence and organization of genes encoding enzymes involved in pyruvate metabolism in Mycoplasma capricolum. 884 61

The rnf genes in Rhodobacter capsulatus are unique nitrogen fixation genes that encode potential membrane proteins (RnfA, RnfD, and RnfE) and potential iron-sulfur proteins (RnfB and RnfC). In this study, we first analyzed the localization and topology of the RnfA, RnfB, and RnfC proteins. By activity and immunoblot analysis of expression of translational fusions to Escherichia coli alkaline phosphatase, RnfA protein was shown to span the chromatophore membrane with its odd-numbered hydrophilic regions exposed to periplasm. By alkaline treatment of membrane fractions and following immunoblot analysis using antibodies against recombinant proteins expressed in E. coli, both RnfB and RnfC proteins were revealed to situate at the periphery of the chromatophore membranes. Second, mutual interaction of the Rnf proteins was analyzed by immunochemical determinations of RnfB and RnfC proteins in rnf mutants and their complemented derivatives. The contents in cellular fractions indicated that RnfB and RnfC stabilize each other and that the presence of RnfA is necessary for stable existence of both proteins. These results support a hypothesis that the Rnf products are subunits of a membrane complex. Finally, we detected homologs of rnf genes in Haemophilus influenzae and Vibrio alginolyticus by data base searches and in E. coli by cloning of a fragment of an rnfA homolog followed by a data base search. Close comparisons revealed that RnfC has potential binding sites for NADH and FMN which are similar to those found in proton-translocating NADH:quinone oxidoreductases and that RnfA, RnfD, and RnfE show similarity to subunits of sodium-translocating NADH:quinone oxidoreductases. We predict that the putative Rnf complex represents a novel family of energy-coupling NADH oxidoreductases.
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PMID:Membrane localization, topology, and mutual stabilization of the rnfABC gene products in Rhodobacter capsulatus and implications for a new family of energy-coupling NADH oxidoreductases. 915 34

Rat liver d-3-phosphoglycerate dehydrogenase was purified to homogeneity and digested with trypsin, and the sequences of two peptides were determined. This sequence information was used to screen a rat hepatoma cDNA library. Among 11 positive clones, two covered the whole coding sequence. The deduced amino acid sequence (533 residues; Mr 56493) shared closer similarity with Bacillus subtilis 3-phosphoglycerate dehydrogenase than with the enzymes from Escherichia coli, Haemophilus influenzae and Saccharomyces cerevisiae. In all cases the similarity was most apparent in the substrate- and NAD+-binding domains, and low or insignificant in the C-terminal domain. A corresponding 2.1 kb mRNA was present in rat tissues including kidney, brain and testis, whatever the dietary status, and also in livers of animals fed a protein-free, carbohydrate-rich diet, but not in livers of control rats, suggesting transcriptional regulation. The full-length rat 3-phosphoglycerate dehydrogenase was expressed in E. coli and purified. The recombinant enzyme and the protein purified from liver displayed hyperbolic kinetics with respect to 3-phosphoglycerate, NAD+ and NADH, but substrate inhibition by 3-phosphohydroxypyruvate was observed; this inhibition was antagonized by salts. Similar properties were observed with a truncated form of 3-phosphoglycerate dehydrogenase lacking the C-terminal domain, indicating that the latter is not implicated in substrate inhibition or in salt effects. By contrast with the bacterial enzyme, rat 3-phosphoglycerate dehydrogenase did not catalyse the reduction of 2-oxoglutarate, indicating that this enzyme is not involved in human D- or L-hydroxyglutaric aciduria.
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PMID:Cloning, sequencing and expression of rat liver 3-phosphoglycerate dehydrogenase. 916 25


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