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Biomedical subjects

F Tanaka

Publications and source records attributed to F Tanaka.

At least 325 records · Page 18Linked 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

Circadian rhythm of plasma corticosteroid in adult female rats: chronological shifts in abnormal lighting regimens and connection with oestrous cycle.

The circadian rhythm of plasma corticosteroid (CS) levels in adult female rats was studied chronologically under the following conditions: normal light-dark (LD), inverted light-dark (DL), constant dark (DD) and constant light (LL). Animals were accustomed to LD condition for 7 days before exposure to each abnormal lighting regimen. Normal circadian rhythm established under LD condition was clearly inverted on the third day of DL regimen, and the inverted rhythm persisted thereafter under DL condition. The circadian CS rhythm persisted essentially unchanged throughout DD condition, but lost its regular periodicity showing "free running" and changed day by day under LL condition. The average CS levels over a 24 h period were higher under LL than under DD condition. Plasma CS levels in each lighting regimen exhibited diurnal variations regardless of the vaginal smear patterns of autopsied animals. Exposure of rats to LL for 21 days made the circadian CS rhythm flat, but induced persistent oestrus in only a few animals. The data suggest that (1) an unexpectedly rapid inversion of the circadian CS rhythm occurs if animals are exposed to inverted light-dark environment; (2) constant darkness seems to be a near-natural environment for rats, and changes little of the pre-established circadian CS rhythm; (3) constant light, on the contrary, is assumed to be a stress for rats, and disrupts the circadian CS rhythm and elevates CS levels; (4) the change in circadian CS rhythm in adult female rats is not mediated by a change in gonadal function and the two conditions may not be connected directly with each other.

Adrenal Cortex Hormones↗
PubMed1974

The effect of pressure on the molecular complex of isoalloxazine and adenine.

The effect of pressure to 10 kilobars on the fluorescence characteristics of flavin mononucleotide (FMN), flavin-adenine dinucleotide (FAD), and on complexes of FMN with adenylic acid (AMP), and with I(-) has been studied. The properties measured include peak location, fluorescence yield, and lifetime. From these results the equilibrium constant K and the rate constant k(+) (*) for complex formation were evaluated as a function of pressure. The pressure dependence of these coefficients shows that the volume of the system decreases upon complex formation and that there is an expansion upon formation of the activated complex (DeltaVdouble dagger is positive). The implications of these results for protein denaturation are mentioned.

Adenine↗