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Biomedical subjects

T Yagi

Publications and source records attributed to T Yagi.

At least 721 records · Page 40Linked to original sources
PubMed1976

Directional non-uniformity of pulsatile intramyocardial pressure.

A method using piezoelectric ceramics was newly devised which permitted measurements of intramyocardial pressure. In open-chest dogs, a directional non-uniformity of the intramyocardial pressure was observed, which may be attributable to the variation in the myocardial fibre orientation.

Animals↗
PubMed1976

Separation of hydrogenase-catalyzed hydrogen-evolution system from electron-donating system by means of enzymic electric cell technique.

An enzymic electric cell was constructed in which the anode was composed of a zinc plate inserted in aqueous NH(4)Cl solution and the cathode was composed of an electrode made of a glassy carbon stick inserted in a reaction mixture containing cytochrome c(3) hydrogenase (H(2):ferricytochrome c(3) oxidoreductase, EC 1.12.2.1) and methylviologen under an atmosphere of N(2). When the circuit was closed, the electric cell formulated as [Formula: see text] was composed, and hydrogenase-catalyzed H(2)-evolution was observed in the cathode of the cell with concomitant flow of an electric current. Thus, the hydrogenase-catalyzed reaction and the electron-donating reaction proceeded at different parts of the cell. This enables us to protect the hydrogenase from the byproducts of the electron-donating system, which might be hazardous to the enzyme.

Journal Article↗
PubMed1976

Properties of purified hydrogenase from the particulate fraction of Desulfovibrio vulgaris, Miyazaki.

The properties of purified hydrogenase [EC 1.12.2.1] solubilized from particulate fraction of sonicated Desulfovibrio vulgaris cells are described. The enzyme was a brownish iron-sulfur protein of molecular weight 89,000, composed of two different subunits (mol. wt.: 28,000 and 59,000), and it contained 7-9 iron atoms and 7-8 labile sulfide ions. Molybdenum was not detected in the preparation. The absorption spectrum of the enzyme was characteristic of iron-sulfur proteins. The millimolar absorbance coefficients of the enzyme were about 164 at 280nm, and 47 at 400nm. The absorption spectrum of the enzyme in the visible region changed upon incubating the enzyme under H2 in the presence of cytochrome c3, but not in its absence. This spectral change was due to the reduction of the enzyme. The absorbance ratio at 400nm of the reduced and the oxidized forms of the enzyme was 0.66. The activity of the enzyme was hardly affected by metal-complexing agents such as cyanide, azide, 1,10-phenanthroline, etc., except for CO, which was a strong inhibitor of the enzyme. The activity was inhibited by SH-reagents such as p-chloromercuribenzenesulfonate. The enzyme was significantly resistant to urea, but susceptible to sodium dodecyl sulfate. These properties were very similar to those of clostridial hydrogenase [EC 1.12.7.1], in spite of differences in the acceptor specificity and subunit structure.

Amino Acids↗
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↗