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H Inokuchi

Publications and source records attributed to H Inokuchi.

At least 199 records · Page 11Linked to original sources
PubMed1979

Hydrogenase activity in the dry state: isotope exchange and reversible oxidoreduction of cytochrome c3.

Hydrogenase (hydrogen:ferricytochrome c3 oxidoreductase, EC 1.12.2.1) catalyzes three types of reactions, i.e., (1) conversion between hydrogen modifications, para-H2 and ortho-H2, (2) exchange reaction between hydrogen isotopes, and (3) reversible oxidoreduction of an electron carrier with H2 and protons. We observed that purified desulfovibrio hydrogenase in the dry state could catalyze not only the conversion and exchange reactions (Yagi, T., Tsuda, M., Mori, Y. and Inokuchi, H. (1969) J. Am. Chem. Soc. 91, 2801) but also the reversible oxidoreduction of the electron carrier, cytochrome c3 with H2. The rate of the conversion was in the range from 0.1 to 0.65 mol H2 converted per mol hydrogenase per s, and the ratio of the conversion rate to the exchange rate was near 5. The rate of oxidoreduction of cytochrome c3 in the dry state was 0.015 mol H2 taken up in the forward reaction and 0.003 mol H2 released in the reverse reaction per mol hydrogenase per s. The process of these reactions could be explained by the observations that the hydrogenase molecule in the dry state has protons which are directly exchangeable with H2 during catalytic process. The reversible oxidoreduction of cytochrome c3 is also explained by inter- and intramolecular electron transfer among cytochrome c3 molecules.

Cytochrome c Group↗
PubMed1979

Crystallographic data for cytochrome c3 from two strains of Desulfovibrio vulgaris, Miyazaki.

Two crystalline forms of cytochrome c3 isolated from two strains of Desulfovibrio vulgaris, Miyazaki, tentatively designated as D. vulgaris, Miyazki F and D. vulgaris, Miyazaki K, have been found. Both belong to the orthorhombic system, space group P2(1)2(1)2(1), but have different cell dimensions; a=54.1, b=68.9 and c=35.0 A for D. vulgaris, Miyazaki F, and a=43.5, b=41.2, and c=62.9 A for D. vulgaris, Miyazaki K. The asymmetric unit of each crystal contains one molecule of cytochrome c3.

Cytochromes↗
PubMed1976

Excision and duplication of su3+-transducing fragments carried by bacteriophage phi 80. I. Novel structure of phi 80sus2psu3+ DNA molecule.

DNA molecules of phi 80sus2psu3+ and phi 80dsu3+ isolated by Andoh and Ozeki (1968) were studied by the electron microscope heteroduplex method. The phi 80sus2psu3+ and phi 80dsu3+ DNA lengths were found to be 108.7 and 103.3% of the phi 80 DNA, respectively. The phi 80sus2psu3+/phi 80 heteroduplex shows an insertion loop of 8.7% of the phi 80 DNA which migrates from 7.7 to 9.7%, as measured relative to the left (0%) and right (100%) termini of the mature phi 80 DNA molecule. The region of loop migration occupies the central region of the phi 80 head gene cluster. The presence of su3+-containing Escherichia coli DNA of 6.7% phi 80 unit flanked by two homologous regions of phage DNA of 2.0% of phi 80 unit gives rise to a movable insertion loop. In phi 80dsu3+, from which phi 80sus2psu3+ was derived, 50.5% of the phi 80 DNA at the left arm was replaced by E. coli DNA containing the su3+ gene, equivalent to about 53.8% phi 80 unit in length. The phi 80sus2psu3+/phi 80dsu3+ heteroduplex appears as a double-stranded molecule that bifurcates into two clearly visible single-stranded regions, rejoins, bifurcates, and rejoins again. The middle double-stranded stretches of 6.7% phi 80 unit correspond to the E. coli DNA inserted in phi 80sus2psu3+. Therefore the transducing fragment carried by phi 80sus2psu3+ originates from the inside region of the transducing fragment of defective phage phi 80dsu3+ by at least two illegitimate recombination events.

Chromosome Mapping↗
PubMed1975

A new assay method for hydrogenase based on an enzymic electrode reaction. The enzymic electric cell method.

A new assay method for hydrogenase [EC 1.12.2.1] based on the enzymic electrode reaction of H2-H+ equilibrium has been established. The method is based on the experimental fact that the short-circuit current of the electric cell composed of an electrode with hydrogenase and methylviologen as the mediator of H2-H+ equilibrium and a saturated calomel electrode as the counter electrode, is practically proportional to the amount of hydrogenase in the cell. The new method is referred to as the "enzymic electric cell method." This technique has applications not only to routine activity assay but also to the direct determination of the time course of enzyme denaturation, which has not previously been possible.

Cytochrome c Group↗