Biomedical subjects

K Yagi

Publications and source records attributed to K Yagi.

At least 757 records · Page 42Linked to original sources

PubMed1975

Structure and function of D-amino acid oxidase. IX. Changes in the fluorescence polarization of FAD upon complex formation.

1. The fluorescence polarization, P, of FAD increased on complex formation with the apoenzyme of D-amino acid oxidase [D-amino acid: O2 ocidoreductase (deaminating), EC 1.4.3.3]. The time course of the increase was monophasic. The values of P were extimated to be 0.04, 0.4, and 0.4 for FAD, the enzyme and the enzyme-benzoate complex, respectively. 2. The value of P of the enzyme is dependent on its concentration, indicating that the degrees of dissociation of FAD in the monomer and dimer are different. The dissociation constant was calculated to be 7 times 10-minus 7 M for the monomeric form of the enzyme. This value is far larger than the value for the dimeric form of the enzyme, 1 times 10-minus 8 M, calculated from equilibrium dialysis data. 3. Changes in fluorescence polarization of the enzyme due to changes in solution pH or temperature can be explained in terms of the monomer-dimer equilibrium.

Animals↗

PubMed1975

Myosin from molluscan abalone, Haliotis discus. Isolation and enzymatic properties.

Actomyosin was extracted from smooth muscle of molluscan abalone with 0.1 M PPit pH 6.4. Myosin was separated from the actomyosin by centrifugation at 100,000 X g in the presence of 5 mM ATP and 10 mM MgCl2. Myosin in the supernatant was further purified by gel filtration on a Sepharose 4B column. Paramyosin contamination of the actomyosin preparation interfered with the isolation of myosin and complete removal of actin and paramyosin from the myosin has not been accomplished. The myosin appeared to consist of a single f-chain and a single g-chain, as examined by SDS-disc electrophoresis in 8 or 13.7% acrylamide gel. The ATPase [EC 3.6.1.3] activity of this myosin in 0.5 M KCL at neutral pH and at 0 degrees was rather unstable and decreased by 10-20% per day. The effects of rho-chloromercuribenzoate and EDTA on the ATPase activity were similar to those observed with other smooth muscle myosin but the dependence upon pH or KCL concentration was different.

Adenosine Triphosphatases↗

PubMed1975

Flavins in chick embryo.

During incubation of fertilized hen egg, flavin in egg white migrated into the embryo. The total amount of flavins in the embryo increased with development. On the 7th day of incubation, molar ratio of riboflavin and flavin nucleotides in the embryo was already similar to that of animal tissues. Even though appreciable amounts of FMN and FAD were found in egg white, flavin nucleotides found in the embryo in its early embryonic life cannot be simply ascribed to the migration of these nucleotides originally present in egg white, because egg yolk contains no appreciable amount of flavin nucleotides; the possibility that flavin nucleotides are synthesized from riboflavin in the embryo in its early embryonic life still exists.

Age Factors↗

PubMed1975

Studies on myoinositol. Effects of caffeine and theophylline on incorporation of myoinositol into phosphatidylinositol in rat liver homogenate.

Both caffeine and theophylline, which were known to be potent inhibitors of cyclic-AMP phosphodiesterase, stimulated the incorporation of myoinositol into phosphatidylinositol in rat liver homogenate. However, cyclic-AMP had no effect. The effect of dibutyryl-cyclic-AMP differed with different concentrations. These results suggest that the stimulation cannot be explained by the increase in the amount of cyclic-AMP. This view was supported by the fact that papaverine, cyclic-AMP phosphodiesterase inhibitor, did not stimulate the incorporation and imidazole, the phosphodiesterase stimulator, did not inhibit the incorporation, and that adenylcyclase stimulators, epinephrine and glucagon, did not stimulate the incorporation.

Animals↗

PubMed1975

Electron microscopic study on the lens of riboflavin-deficient albino rat.

Although cataract was recognized as a typical symptom of ariboflavinosis soon after the discovery of riboflavin, some reports appeared thereafter which denied its occurrence. In the present study electron microscopic examination of the lens of rat fed on synthetic riboflavin-deficient diet revealed swelling degeneration of mitochondria and vacuolation of cytoplasm of the epithelial cells of the lens. These changes are similar to those observed in the initial period of cataract caused by other agents.

Animals↗

PubMed1975