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Biomedical subjects

Y Tani

Publications and source records attributed to Y Tani.

At least 325 records · Page 18Linked to original sources
PubMed1977

Action of 5-(2-thienyl)valeric acid as a biotin antagonist.

5-(2-Thienyl)valeric acid (TVA), a biotin analogue which can be easily prepared through chemical process, inhibited the growth of a biotin synthesizing Rhodotorula glutinis. The growth inhibition was reversed by the addition of biotin. Among biotin intermediates, dethiobiotin and 7,8-diaminopelargonic acid reversed the inhibition by TVA, while 7-keto-8-amino-pelargonic acid and pimelic acid did not. From these results, it was concluded that TVA is a biotin antagonist which probably acts as an inhibitor of biotin biosynthesis.

Biotin↗
PubMed1977

Dependency representing Markov properties of spike trains recorded from central single neurons.

Neuronal spike trains are regarded as stochastic point processes. To estimate the order and the vale of Markov properties of the adjacent interspike interval sequences, we have proposed new statistics "dependency" Dm for discrete variable and "simplified dependency" Dm for continuous variable in the stationary point processes, and Dm(t) for discrete variable in the non-stationary point processes. With the use of Dm it was shown that the maintained activity of the neurons of the mesencephalic reticular formation and red nucleus (tonic neuron groups) revealed higher order and larger values of Markov properties than that of the optic tract (OT) fibers and lateral geniculate nucleus neurons (phasic neuron groups) in cats. By employing Dm(t) it was shown that the value of the 1st order Markov properties of OT spike trains induced by the light spot presentation became to increase earlier in Y-fibers than in X-fibers; and that the value for Y-fibers returned to the maintained level in a short time, while the maximum value for X-fibers continued up to the light-off. The differentiation is considered to have a decided functional significance. From these results it is suggested that dependency code represents the stability of neuronal functions.

Action Potentials↗
PubMed1976

Purification and characterization of butyrylcholine-hydrolyzing enzyme from Pseudomonas polycolor.

A butyrylcholine-hydrolyzing enzyme (EC 3.1.1.-) fo Pseudomonas polycolor IFO 3918 was purified approximately 9270-fold with a recovery of 9.9% by use of chromatographic techniques. The enzyme preparation appeared to be homogeneous when subjected to electrophoretic and ultracentrifugational analyses. The molecular weight was determined as approximately 59000 by gel filtration. Isoelectric focusing electrophoresis revealed that the enzyme had an isoelectric point around pH 5.1. The enzyme catalyzed the hydrolysis of butyrylcholine with the miximum activity among various esters tested, and split benzoylcholine, propionylcholine and some aliphatic esters, but did not attact acetylcholine. The estimated value of Km at pH 7.5 and 25 degrees C was 7-10(-4) M for butyrylcholine. The enzyme was irreversibly inhibited by organophosphorus compounds and carbamates, such as diisopropylphosphofluoridate and eserine. The enzyme was inhibited by some compounds, such as atropine and quinidine. Auaternary ammonium salts showed an inhibitory effect on the enzyme resembling co-operative inhibition.

Atropine↗
PubMed1976

Alcohol oxidases of Kloeckera sp. and Hansenula polymorpha. Catalytic properties and subunit structures.

1. Alcohol oxidase (alcohol: oxygen oxidoreductase) of a thermophilic methanol-utilizing yeast, Hansenula polymorpha DL-1, was isolated in crystalline form. 2. This alcohol oxidase of H. polymorpha was more stable to heat than was the enzyme of Kloeckera sp. This difference in heat stability is compatible with the difference in growth temperatures for both yeasts. 3. The crystalline alcohol oxidases of both yeast oxidized the lower primary alcohols (C-2 to C-4) as well as methanol. The apparent Km values for the methanol of Kloeckera and H. polymorpha enzymes were 0.44 and 0.23 mM, respectively. The enzymes could also oxidize formaldehyde to formate, and were inactivated by relatively low concentrations of hydrogen peroxide. 4. The molecular weight for both enzymes was calculated to be about 670000. Each enzyme is composed of eight identical subunits (molecular weight 83000) and contains eight moles of FAD as the prosthetic group. The NH2-terminal and COOH-terminal amino acids of H. polymorpha enzyme were identified as alanine and phenylalanine, respectively. The octameric subunits model of each enzyme was confirmed by electron micrographs, which showed an octad aggregate, composed of two tetragons face to face.

Alcohol Oxidoreductases↗
PubMed1976

A butyrylcholinesterase inhibitor produced by Penicillium sp. no. C-81 and its identity with mycelianamide.

A screening aimed at obtaining a cholinesterase inhibitor of microbial origin was carried out using Pseudomonas butyrylcholinesterase. A mycelium-extract of a fungus strain, belonging to the genus Penicillium, was found to produce such an enzyme inhibitor. The inhibitor was purified and crystallized as colorless leaflets. From physical and chemical studies, the inhibitor was identified as being identical with an antibiotic, mycelianamide, though this compound was not known to have enzyme inhibitor activity. The kinetics of the inhibition of Pseudomonas butyrylcholinesterase were also studied. Horse serum cholinesterase and hog liver carboxylesterase were also inhibited by the isolated Penicillium C-81 inhibitor, but lipase and acetylcholinesterase were not.

Animals↗