Biomedical subjects

Y Eguchi

Publications and source records attributed to Y Eguchi.

At least 253 records · Page 14Linked to original sources

PubMed1976

Exchange reactions catalyzed by methioninase from Pseudomonas putida. Isolation and characterization of the exchange products.

Gel-electrophoretically homogeneous methioninase [L-methionine methanethiol-lyase (deaminating), EC 4.4.1.11] of Pseudomonas putida, which catalyzes alpha, beta- and alpha, gamma-eliminations from S-substituted amino acids, could also catalyze a variety of beta- and gamma-exchange reactions, according to the following equations: RSCH2CH(NH2)COOH+R'SH in equilibrium R'SCH2CH(NH2)COOH+RSH (beta-exchange) and RSCH2CH2CH(NH2)COOH+R'SH in equilibrium R'SCH2CH2CH(NH2)COOH+RSH (gamma-exchange), where R'SH represents an exogeneously added alkanethiol or a substituted thiol. Related amino acids not available for elimination reactions appeared to be inert as substrates for exchange. The maximum activity for the exchange reactions was observed at pH 8.5 in potassium pyrophosphate buffer. The activity increased linearly with the increase in protein concentration from zero to 3.0 mug per ml, and with incubation time up to at least 15 min at 30 degrees. Some of the exchange reaction products were purified by a combination of paper and ion exchange chromatographies, and charcoal treatment: their structures were confirmed by physicochemical methods including elemental analysis and proton magnetic resonance, infrared, and mass spectrometries.

Carbon-Sulfur Lyases↗

PubMed1976

Failure of estradiol benzoate given after birth to prevent the adrenal glands from shrinking in newborn rats.

Two hr after birth, newborn rats were given a subcutaneous injection of 0.01 mg estradiol benzoate dissolved in 0.05 ml sesame oil. Other siblings were given sesame oil alone. Autopsy was performed on days 1, 2 and 3 after birth. Gravimetric and histologic examinations of the adrenals from these animals and from normal littermate controls were made together with the determination of plasma corticosterone concentrations. In all the three groups of rats, estrogen-treated, oil-treated and non-treated, the weight of the adrenal glands declined with a concomitant decrease in the plasma corticosterone concentrations. The results indicate that estradiol benzoate, when given after birth, does not prevent the neonatal adrenal from shrinking.

Adrenal Glands↗

PubMed1976

Changes in the weight of the adrenal glands and in the concentration of plasma corticosterone in perinatal rats after prenatal treatment with oestadiol benzoate.

On day 20 of gestation, foetal rats received a subcutaneous injection of 0-01 mg oestradiol benzoate dissolved in 0-05 ml sesame oil; foetuses in other litters were given sesame oil alone. Autopsy was performed on day 22 of gestation, at delivery or at various times after birth. Gravimetric and histological observations of the adrenals from oestradiol-treated, oil-treated and intact litter-mate control foetal and neonatal rats were performed together with determination of plasma corticosterone concentrations. Activity of 3 phi-ol dehydrogenase was also examined histochemically in the adrenals from these animals. The results indicated that oestradiol benzoate when given prenatally prevented the neonatal decline of adrenal weight and adrenocortical cell size. In normal or oil-treated rats, plasma corticosterone concentration was greatly increased during delivery and 2 h after birth, declining up to 12 h after birth. Oestradiol benzoate prevented this perinatal increase and suppressed the activity of 3 phi-ol dehydrogenase in the perinatal adrenal cortices.

Adrenal Glands↗

PubMed1976

Biosynthesis of formycin. Incorporation and distribution of labeled compounds into formycin.

1. Two carbons, carbon-2 and one of carbons-3 to -5, of lysine seemed likely to be incorporated into one of carbon of the chromophore moiety of formycin. 2. From the results of radioisotopic studies with glutamate, gamma-amino-n-butyrate or organic acids related to tricarboxylic acid cycle, the important role of glutamate in the biosynthesis of formycin was strongly suggested. 3. The incorporation of nitrogen(s) of lysine into three nitrogens, including two nitrogens of pyrazole ring, of formycin was suggested by mass spectroscopy. 4. Ribose was estimated as a direct precursor moiety of formycin, whereas the biosynthesis of ribose was shown to occur via the pathway other than hexose monophosphate shunt or glucuronate pathway. 5. In replacement culture, the salvage synthesis of formycin from its chromophore moiety was not observed and it was also evident that the chromophore moiety or pyrazofurin (pyrazomycin) inhibited the biosynthesis of formycin.

Adenine↗

PubMed1975

Crystallization and properties of rat liver malate dehydrogenase (decarboxylating) (NADP).

Rat liver malate dehydrogenase (decarboxylating) (NADP) ((L-malate: NADP) oxidoreductase (oxaloacetate-decarboxylating), EC 1.1.1.40) was purified and crystallized from medium containing 30 mM Tris-HCl buffer (pH 7.7), 5 mM MgCl2 and 2 mM 2-mercaptoethanol. The enzyme formed rhomboid crystals free from coenzyme, and appeared homogeneous on isoelectric focusing. The crystalline enzyme had an isoelectric point of pH 6.3. Amino acid analysis showed that it contained more acidic amino acids than basic ones.

Amino Acids↗

PubMed1975

Granular cells in the juxtaglomerular apparatus in perinatal rats.

Granular cell indices (GCI; Dunihue and Robertson, '57) in kidneys of fetal and newborn rats were determined by examining sections stained with Bowie's technique. Some fetuses were delivered prematurely by Caesarean section a day earlier than the expected delivery, and were then nursed by a foster mother. Similarly, postmature Caesarean newborn rats were obtained; retention one day beyond the normal gestation was induced by maternal progesterone injections. The GCI was strikingly increased within a day after birth, followed by an immediate decrease therafter. This was also observed in both premature and postmature rats. It seems that this temporary increase of the GCI is not attributable solely to the age of rat, but follows only the separation from the maternal environment.

Animals↗

PubMed1975

Exchange reactions catalyzed by methioninase from Pseudomonas putida.

Highly purified methioninase from Pseudomonas putida, which catalyzes alpha, gamma-elimination reactions of homocysteine and its S-substituted derivatives as well as alpha, beta-elimination reactions of cysteine and its derivatives, was found to catalyze exchange reactions between the substituent at the gamma-carbon of homocysteine substrates and exogenously added alkanethiols, forming the corresponding S-alkylhomocysteines. It also catalyzed similar beta-exchange reactions between cysteine and alkanethiols. Thus, all the substrates for the methioninase-catalyzed elimination reactions also appear to be available for the exchange reactions.

Carbon-Sulfur Lyases↗

PubMed1975

Hypothalamic control of the pituitary-testicular relation in fetal rats: measurement of collective volume of Leydig cells.

On the 20th day of gestation in pregnant rats, the male fetuses were subjected to surgical hypophysectomy by decapitation or to intracranial paraffin injection which compressed the fetal brain. Autopsy was done on the 22nd day of gestation. The collective volume of Leydig cells in the left fetal testis was estimated by Chalkley's method. Decapitation of a fetus caused a significant retardation in increase of the collective volume of Leydig cells 2 days later. In fetuses given an intracranial paraffin injection, the Leydig cell volume was increased significantly compared with normal fetuses on the 20th day of gestation but was far smaller than that in their intact littermates. This effect of paraffin compression was completely prevented by injections of LRH. The Leydig cell volume remained extremely small in decapitated fetuses given LRH. The observations suggest that in the male rat the hypothalamus begins to govern a pituitary gonadotropic function before birth.

Animals↗

PubMed1975

Biosynthesis of formycin. Formation of formycin from formycin B.

1. In replacement culture with a formycin-producing strain. Steptomyces sp. MA406-A-1, exogenously added formycin B was quantitatively converted to formycin and the conversion was inhibited by adding the chromophore moiety of formycin. 2. The in vitro experiments revealed that the novel enzyme(s) catalyzing the formation and formycin from asparate and formycin B, but not from formycin B monophosphate, was present in this organism. The action of the partially purified enzyme(s) was also inhibited by the chromophore moiety of formycin, whereas the moiety showed no inhibitory effect on the actions of adenylosuccinate synthetase and adenylosuccinate lyase. 3. Adenine auxotrophs lacking either adenylosuccinate synthetase or adrenylosuccinate lyase were derived from strain MA406-A-1 and these auxotrophs were found to readily convert formycin B to formycin in replacement culture. From these results, it was estimated that, under the conditions of replacement culture, formycin B would be converted to formycin in vivo by the action of novel enzyme(s) rather than by the action of enzyme system including adenylosuccinate synthetase and adenylosuccinate lyase.

Adenine↗

PubMed1974