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Query: UMLS:C0519030 (Klebsiella)
21,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The stereochemistry of the hydrogen transfer to NAD catalyzed by ribitol dehydrogenase (ribitol:NAD 2-oxidoreductase, EC 1.1.1.56) from Klebsiella pneumoniae and D-mannitol-1-phosphate dehydrogenase (D-mannitol-1-phosphate:NAD 2-oxidoreductase, EC 1.1.1.17) from Escherichia coli was investigated. [4-3H]NAD was enzymatically reduced with nonlabelled ribitol in the presence of ribitol dehydrogenase and with nonlabelled D-mannitol 1-phosphate and D-mannitol 1-phosphate dehydrogenase, respectively. In both cases the [4-3H]-NADH produced was isolated and the chirality at the C-4 position determined. It was found that after the transfer of hydride, the label was in both reactions exclusively confined to the (4R) position of the newly formed [4-3H]NADH. In order to explain these results, the hydrogen transferred from the nonlabelled substrates to [4-3H]NAD must have entered the (4S) position of the nicotinamide ring. These data indicate for both investigated inducible dehydrogenases a classification as B or (S) type enzymes. Ribitol also can be dehydrogenated by the constitutive A-type L-iditol dehydrogenase (L-iditol:NAD 5-oxidoreductase, EC 1.1.1.14) from sheep liver. When L-iditol dehydrogenase utilizes ribitol as hydrogen donor, the same A-type classification for this oxidoreductase, as expected, holds true. For the first time, opposite chirality of hydrogen transfer to NAD in one organic reaction--ribitol + NAD = D-ribu + NADH + H--is observed when two different dehydrogenases, the inducible ribitol dehydrogenase from K. pneumoniae and the constitutive L-iditol dehydrogenase from sheep liver, are used as enzymes. This result contradicts the previous generalization that the chirality of hydrogen transfer to the coenzyme for the same reaction is independent of the source of the catalyzing enzyme.
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PMID:Chirality of the hydrogen transfer to the coenzyme catalyzed by ribitol dehydrogenase from Klebsiella pneumoniae and D-mannitol 1-phosphate dehydrogenase from Escherichia coli. 18 37

Chirality, Hydrogen Transfer, myo-Inositol Dehydrogenase. The chirality of the hydrogen transfer to NAD catalyzed by myo-inositol dehydrogenase (myo-Inositol: NAD 2-oxydoreductase, EC 1.1.1.18) from Klebsiella pneumoniae (formerly classified taxonomically as Aerobacter aerogenes or Kleb siella aerogenes) was investigated. [4-3H] NAD was enzymatically reduced to [4-3H] NADH with non-labeled myoinositol and myo-inositol dehydrogenase. The stereochemistry of the prochiral center at C4 of the NADH produced was determined. It was found that the label was exclusively located at the (4S) position of the produced NADH. Since the hydrogen transferred from non-labeled myo-inositol to [4-3H] NAD must have entered the opposite of (R) position, myo-inositol dehydrogenase from K. pneumoniae should be classified as an (R) or A-type enzyme with respect to the stereochemistry of the hydrogen transfer to NAD.
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PMID:Chirality of the hydrogen transfer to NAD catalyzed by myo-inositol dehydrogenase from Klebsiella pneumoniae. 18 32

L-Sorbose is oxidized to 2-keto-L-gulonic acid (KGA) via the following sequence of reactions which we call the "sorbosone pathway": L-sorbose in equilibrium L-sorbosone leads to KGA. The first step is reversible and is mediated by enzymes found in a soluble fraction obtained from Pseudomonas putida ATCC 21812. Although no cofactor requirements were found for the forward reaction, the reverse reaction clearly required NADH. Enzymes for this NADH-dependent synthesis of L-sorbose could be differentiated on the basis of molecular weights. The second step in the sorbosone pathway is catalyzed by a particulate enzyme found in extracts from P. putida and Gluconobacter melanogenus IFO 3293. The rate limiting reaction in the sorbosone pathway is the synthesis of L-sorbosone. In addition to P. putida, Klebsiella pneumoniae (ATCC 27858) and Serratia marcescens (ATCC 27857) also contain the enzymes which catalyze the reactions of the sorbosone pathway. Two of the bacteria studied, P. putida and G. melanogenus, also contain an enzyme involved in the further metabolism of KGA to L-idonic acid. This enzyme, referred to as KGA-reductase, is found in the soluble fraction of cell-free extracts and is dependent on NADH or NADPH.
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PMID:New mechanisms for the biosynthesis and metabolism of 2-keto-L-gulonic acid in bacteria. 118 75

Citrate is fermented by Klebsiella pneumoniae to 2 acetate, 0.5 formate and 1.2 CO2. The formation of less than 1 formate and greater than 1 CO2 per citrate can be accounted for by the oxidation of formate to CO2 in order to provide reducing equivalents for the assimilation of citrate into cell carbon. A membrane-bound electron transport chain is apparently involved in NADH synthesis by these cells. The electrons from formate oxidation to CO2 are used to reduce ubiquinone to ubiquinol by membrane-bound formate dehydrogenase and ubiquinol further delivers its electrons to NAD+, if this endergonic reaction is powered by delta mu Na+. The endogenous NADH level of K. pneumoniae cells thus increased in the presence of formate in response to a delta pNa+ greater than -100 mV. NADH formation was completely abolished in the presence of oxygen or after addition of hydroxyquinoline-N-oxide, a specific inhibitor of the Na(+)-translocating NADH:ubiquinone oxidoreductase. The increase of endogenous NADH was dependent on the delta pNa+ applied to the cells. Inverted membrane vesicles of K. pneumoniae catalysed the reduction of NAD+ to NADH with formate as electron donor after application of delta mu Na+ of about 120 mV consisting of delta pNa+ of 60 mV and delta psi of the same magnitude. Neither the delta pNa+ nor the delta psi of this size alone was sufficient to drive the endergonic reaction. Strictly anaerobic conditions were required for NADH formation and hydroxyquinoline-N-oxide completely inactivated the reaction.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:NADH formation by Na(+)-coupled reversed electron transfer in Klebsiella pneumoniae. 150 43

Three classes of heme proteins, commonly designated hydroperoxidases, are involved in the metabolism of hydrogen peroxide: catalases, peroxidases, and catalase-peroxidases. While catalases and peroxidases are widely spread in animals, plants, and microorganisms, catalase-peroxidases were characterized only in prokaryotes. We report here, for the first time, on a catalase-peroxidase in a eukaryotic organism. The enzyme was purified from the fungal wheat pathogen Septoria tritici, and is one of three different hydroperoxidases synthesized by this organism. The S. tritici catalase-peroxidase, designated StCP, is similar to the enzymes previously isolated from the bacteria Rhodobacter capsulatus, Escherichia coli, and Klebsiella pneumoniae, although it is significantly more sensitive to denaturing conditions. In addition to its catalatic activity StCP catalyzes peroxidatic activity with o-dianisidine, diaminobenzidine, pyrogallol, NADH, and NADPH as electron donors. The enzyme is a tetramer with identical subunits of 61,000 Da molecular weight. StCP shows a typical high-spin ferric heme spectrum with a Soret band at 405 nm and a peak at 632 nm, and binding of cyanide causes a shift of the Soret band to 421 nm, the appearance of a peak at 537 nm, and abolition of the peak at 632 nm. Reduction with dithionite results in a decrease in the intensity of the Soret band and its shift to 436 nm, and in the appearance of a peak at 552 nm. The pH optimum is 6-6.5 and 5.4 for the catalatic and peroxidatic activities, respectively. Fifty percent of the apparent maximal activity is reached at 3.4 mM and 0.26 mM for the catalatic and peroxidatic activities, respectively. The enzyme is inactivated by ethanol/chloroform, and is inhibited by KCN and NaN3, but not by the typical catalase inhibitor 3-amino-1,2,4-triazole.
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PMID:Purification and characterization of a catalase-peroxidase from the fungus Septoria tritici. 160 41

In the cofermentation of glycerol with a sugar by Lactobacillus brevis and Lactobacillus buchneri, a 1,3-propanediol:NAD+ oxidoreductase provides an additional method of NADH disposal. The enzyme has been purified from both L. brevis B22 and L. buchneri B190 and found to have properties very similar to those reported for the enzyme from Klebsiella pneumoniae. The enzymes required Mn2+ and are probably octamers with a molecular mass of 350 kDa. Although not absolutely specific for 1,3-propanediol when tested as dehydrogenases, the enzymes have less than 10% activity with glycerol, ethanol, and 1,2-propanediol. These properties contrast sharply with those of a protein isolated from another Lactobacillus species (L. reuteri) that ferments glycerol with glucose and previously designated a 1,3-propanediol dehydrogenase.
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PMID:1,3-Propanediol:NAD+ oxidoreductases of Lactobacillus brevis and Lactobacillus buchneri. 162 79

In some bacteria, an Na+ circuit is an important link between exergonic and endergonic membrane reactions. The physiological importance of Na+ ion cycling is described in detail for three different bacteria. Klebsiella pneumoniae fermenting citrate pumps Na+ outwards by oxaloacetate decarboxylase and uses the Na+ ion gradient thus established for citrate uptake. Another possible function of the Na+ gradient may be to drive the endergonic reduction of NAD+ with ubiquinol as electron donor. In Vibrio alginolyticus, an Na+ gradient is established by the NADH: ubiquinone oxidoreductase segment of the respiratory chain; the Na+ gradient drives solute uptake, flagellar motion and possibly ATP synthesis. In Propionigenium modestum, ATP biosynthesis is entirely dependent on the Na+ ion gradient established upon decarboxylation of methylmalonyl-CoA. The three Na(+)-translocating enzymes, oxaloacetate decarboxylase of Klebsiella pneumoniae, NADH: ubiquinone oxidoreductase of Vibrio alginolyticus and ATPase (F1F0) of Propionigenium modestum have been isolated and studied with respect to structure and function. Oxaloacetate decarboxylase consists of a peripheral subunit (alpha), that catalyses the carboxyltransfer from oxaloacetate to enzyme-bound biotin. The subunits beta and gamma are firmly embedded in the membrane and catalyse the decarboxylation of the carboxybiotin enzyme, coupled to Na+ transport. A two-step mechanism has also been demonstrated for the respiratory Na+ pump. Semiquinone radicals are first formed with the electrons from NADH; subsequently, these radicals dismutate in an Na(+)-dependent reaction to quinone and quinol. The ATPase of P. modestum is closely related in its structure to the F1F0 ATPase of E. coli, but uses Na+ as the coupling ion. A specific role of protons in the ATP synthesis mechanism is therefore excluded.
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PMID:Mechanisms of sodium transport in bacteria. 197 Jun 50

The bacterium Klebsiella pneumoniae synthesizes three different types of catalase: a catalase-peroxidase, a typical catalase and an atypical catalase, designated KpCP, KpT and KpA, respectively (Goldberg, I. and Hochman, A. (1989) Arch. Biochem. Biophys. 268, 124-128). KpCP, but not the other two enzymes, in addition to the catalatic activity, catalyzes peroxidatic activities with artificial electron donors, as well as with NADH and NADPH. Both KpCP and KpT are tetramers, with heme IX as a prosthetic group, and they show a typical high-spin absorption spectrum which is converted to low-spin when a cyanide complex is formed. The addition of dithionite to KpCP causes a shift in the absorption maxima typical of ferrous heme IX. KpCP has a pH optimum of 6.3 for the catalatic activity and 5.2-5.7 for the peroxidatic activity, and relatively low 'Km' values: 6.5 mM and 0.65 H2O2 for the catalatic and peroxidatic activities, respectively. The activity of the catalase-peroxidase is inhibited by azide and cyanide, but not by 3-amino-1,2,4-triazole. KpT has wide pH optimum: 5-10.5 and a 'Km' of 50 mM H2O2, it is inhibited by incubation with 3-amino-1,2,4-triazole and by the acidic forms of cyanide and azide. A significant distinction between the typical catalase and the catalase-peroxidase is the stability of their proteins: KpT is more stable than KpCP to H2O2, temperature, pH and urea.
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PMID:Purification and characterization of a catalase-peroxidase and a typical catalase from the bacterium Klebsiella pneumoniae. 202 29

Membranes of Klebsiella pneumoniae, grown anaerobically on citrate, contain a NADH oxidase activity that is activated specifically by Na+ or Li+ ions and effectively inhibited by 2-heptyl-4-hydroxyquinoline-N-oxide (HQNO). Cytochromes b and d were present in the membranes, and the steady state reduction level of cytochrome b increased on NaCl addition. Inverted bacterial membrane vesicles accumulated Na+ ions upon NADH oxidation. Na+ uptake was completely inhibited by monensin and by HQNO and slightly stimulated by carbonylcyanide-p-trifluoromethoxy phenylhydrazone (FCCP), thus indicating the operation of a primary Na+ pump. A Triton extract of the bacterial membranes did not catalyze NADH oxidation by O2, but by ferricyanide or menadione in a Na+-independent manner. The Na+-dependent NADH oxidation by O2 was restored by adding ubiquinone-1 in micromolar concentrations. After inhibition of the terminal oxidase with KCN, ubiquinol was formed from ubiquinone-1 and NADH. The reaction was stimulated about 6-fold by 10 mM NaCl and was severely inhibited by low amounts of HQNO. Superoxide radicals were formed during electron transfer from NADH to ubiquinone-1. These radicals disappeared by adding NaCl, but not with NaCl and HQNO. It is suggested that the superoxide radicals arise from semiquinone radicals which are formed by one electron reduction of quinone in a Na+-independent reaction sequence and then dismutase in a Na+ and HQNO sensitive reaction to quinone and quinol. The mechanism of the respiratory Na+ pump of K. pneumoniae appears to be quite similar to that of Vibrio alginolyticus.
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PMID:A primary respiratory Na+ pump of an anaerobic bacterium: the Na+-dependent NADH:quinone oxidoreductase of Klebsiella pneumoniae. 254 75

The progress of bioenergetic studies on the role of Na+ in bacteria is reviewed. Experiments performed over the past decade on several bacterial species of quite different taxonomic positions show that Na+ can, under certain conditions, substitute for H+ as the coupling ion. Various primary Na+ pumps (delta mu Na+ generators) are described, i.e., Na+ -motive decarboxylases, NADH-quinone reductase, terminal oxidase, and ATPase. The delta mu Na+ formed is shown to be consumed by Na+ driven ATP-synthase, Na+ flagellar motor, numerous Na+, solute symporters, and the methanogenesis-linked reverse electron transfer system. In Vibrio alginolyticus, it was found that delta mu Na+, generated by NADH-quinone reductase, can be utilized to support all three types of membrane-linked work, i.e., chemical (ATP synthesis), osmotic (Na+, solute symports), and mechanical (rotation of the flagellum). In Propionigenum modestum, circulation of Na+ proved to be the only mechanism of energy coupling. In other species studied, the Na+ cycle seems to coexist with the H+ cycle. For instance, in V. alginolyticus the initial and terminal steps of the respiratory chain are Na+ - and H+ -motive, respectively, whereas ATP hydrolysis is competent in the uphill transfer of Na+ as well as of H+. In the alkalo- and halotolerant Bacillus FTU, there are H+ - and Na+ -motive terminal oxidases. Sometimes, the Na+ -translocating enzyme strongly differs from its H+ -translocating homolog. So, the Na+ -motive and H+ -motive NADH-quinone reductases are composed of different subunits and prosthetic groups. The H+ -motive and Na+ -motive terminal oxidases differ in that the former is of aa3-type and sensitive to micromolar cyanide whereas the latter is of another type and sensitive to millimolar cyanide. At the same time, both Na+ and H+ can be translocated by one and the same P. modestum ATPase which is of the F0F1-type and sensitive to DCCD. The sodium cycle, i.e., a system composed of primary delta mu Na+ generator(s) and delta mu Na+ consumer(s), is already described in many species of marine aerobic and anaerobic eubacteria and archaebacteria belonging to the following genera: Vibrio, Bacillus, Alcaligenes, Alteromonas, Salmonella, Klebsiella, Propionigenum, Clostridium, Veilonella, Acidaminococcus, Streptococcus, Peptococcus, Exiguobacterium, Fusobacterium, Methanobacterium, Methanococcus, Methanosarcina, etc. Thus, the "sodium world" seems to occupy a rather extensive area in the biosphere.
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PMID:The sodium cycle: a novel type of bacterial energetics. 268 58

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