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Biomedical subjects

T Beppu

Publications and source records attributed to T Beppu.

At least 361 records · Page 20Linked to original sources
PubMed1981

Quantitative determination of individual non-sulfated bile acids and sulfated lithocholic acid in serum by mass fragmentography.

Individual non-sulfated bile acids and sulfated lithocholic acid in serum were determined by mass fragmentography. A hexafluoroisopropyl ester-trifluoroacetyl derivative of bile acid was prepared by the method of Imai et al. (J. Chromatogr. 120, 181, 1976). Deuterium labeled deoxycholic acid was used as an internal standard monitoring at m/z 623. Lithocholic acid, deoxycholic acid, chenodeoxycholic acid, ursodeoxycholic acid, and cholic acid were determined by monitoring the intensities of m/z 622, m/z 620, m/z 620, m/z 620, ad m/z 618, respectively. A serum sample of 200 microliters including 500 ng of internal standard was hydrolyzed with strong alkali, then acidified to pH 1 with 2N HCl under cooling on ice, and extracted with diethyl ether immediately. Ether extracts were derivatized without further purification. Besides this assay of non-sulfated bile acids, total serum lithocholic acid including the sulfated form was determined as follows: extraction was performed after mixing the acidified (pH 1 with 2 N HCl) hydrolysate with ether and incubation at 40 degrees C for 2 h. Bile acid peaks in the mass fragmentogram were not affected by other materials in these serum extracts. The average values of individual non-sulfated bile acids in sera from healthy fasting subjects (n=15) were as follows: lithocholic acid, 0.049 micrograms/ml; deoxycholic acid, 0.462 micrograms/ml; chenodeoxycholic acid, 0.671 micrograms/ml; ursodeoxycholic acid, 0.070 icrograms/ml; and cholic acid, 0.217 micrograms/ml. Total lithocholic acid (non-sulfated and sulfated) in sera was 0.166 microgram/ml.

Bile Acids and Salts↗
PubMed1981

Purification of prorennin and production of its antibody.

Prorennin, i.e. the zymogen of rennin, was extracted from fresh calf stomach and purified by ammonium sulfate precipitation, ion exchange chromatography and gel filtration. The purified prorennin was homogeneous as judged by SDS-polyacrylamide gel electrophoresis. A specific antibody to the purified prorennin was induced in rabbits. In a double diffusion test and on immunoelectrophoresis the antibody gave a single precipitin line when run against crude and pure zymogen preparations. In the double diffusion test, the antibody also reacted with a purified rennin but not with gastric proteases (pepsin and pepsinogen) or other proteases (trypsin and Mucor rennin). When the antibody was tested against prorennin and rennin in the double diffusion test, a spur was formed at the junction of the precipitin lines against prorennin and rennin. This result confirms that the two proteins share an antigenically common structure in their molecules and that the activation segment of prorennin contains at least one antigenic determinant.

Animals↗
PubMed1981

Cloning in Escherichia coli of the structural gene of prorennin, the precursor of calf milk-clotting enzyme renin.

Double-stranded cDNA was prepared from prorennin-specific mRNA by sequential actions of reverse transcriptase, DNA polymerase and S1 nuclease, and inserted into the Sa/I site of pBR322 by the poly(dG)-(dC) annealing method. Transformation of Escherichia coli C600 r- m- by the hybrid plasmid yielded transformants containing prorennin cDNA. The presence of the cDNA sequence in these clones was confirmed by both colony hybridization and hybrid-arrested translation of the mRNA in vitro. The largest size of the cloned cDNA was 1,020 bp.

Animals↗
PubMed1980

An essential arginine residue at the substrate-binding site of p-hydroxybenzoate hydroxylase.

p-Hydroxybenzoate hydroxylase (EC 1.14.13.2) was rapidly inactivated by treatment with phenylglyoxal, by a process obeying pseudo-first order kinetics. The reaction with the reagent was also examined by amino acid analyses, radioactivity measurements, and spectrophotometric analyses. Results of these analyses were consistent with each other, which shows that the inactivation was due to modification of argiine residue(s). Addition of saturating amounts of p-hydroxybenzoate (or benzoate) during the treatment resulted in marked protection of the enzyme from the inactivation as well as a significant decrease in modification of arginine residues, while phenol showed no effect. Modification in the absence of p-hydroxybenzoate caused a spectral change in the flavin moiety of the enzyme similar to that due to the enzyme.substrate complex formation, and losses in both the overall activity and the substrate-binding ability accompanied the spectral change. On the other hand, such spectral change was not observed and the substrate-binding ability was retained even after the overall activity had decreased to a great extent when p-hydroxybenzoate as added during the modification treatment. These results suggest that phenylglyoxal (an analogue of the substrate) was incorporatd into the substrate-binding site and that an arginine residue is involved in the site, having an interaction with the carboxylate anion of the substrate.

4-Hydroxybenzoate-3-Monooxygenase↗
PubMed1980

Physicochemical and catalytic properties of thermostable malate dehydrogenase from an extreme thermophile Thermus flavus AT-62.

Physicochemical and catalytic properties of thermostable malate dehydrogenase (L-malate:NAD+ oxidoreductase, EC 1.1.1.37), isolated from an extreme thermophile, Thermus flavus AT-62, were studied. The enzyme had a molecular weight of 67,000 and consisted of two subunits with an identical molecular weight. The helical content of the enzyme was estimated to be about 25% from the circular dichroism spectrum. The amino acid composition of the thermophilic enzyme was similar to that of its mesophilic counterparts. Titration with 5,5'-dithiobis(2-nitrobenzoic acid) showed that the enzyme contained only one sulfhydryl group per subunit. Substrate inhibition by oxaloacetate was observed. The inhibition decreased with increasing temperature, but was still significant at 60 degrees C. The enzyme was remarkably heat stable, without losing activity after incubation at 90 degrees C for 60 min. The melting temperature of the secondary structure of the enzyme was 96 degrees C.

Amino Acids↗
PubMed1980

L-Alloisocitrate dehydrogenase and oxalosuccinate decarboxylase from a Pseudomonas sp. utilizing L-alloisocitrate.

Two novel enzymes, NAD+-linked L-alloisocitrate (erythro-Ls-isocitrate) dehydrogenase and oxalosuccinate decarboxylase, were found and purified from a strain of Pseudomonas isolated as an L-alloisocitrate utilizing bacterium. The former enzyme catalyzes a reversible oxidation-reduction between L-alloisocitrate and oxalosuccinate which favors oxalosuccinate reduction. The latter enzyme catalyzes rapid decarboxylation of oxalosuccinate to alpha-ketoglutarate and CO2. Both enzymes require no metals for their activities. Complete oxidative decarboxylation of L-alloisocitrate to alpha-ketoglutarate occurs as a result of the sequential reactions catalyzed by these two enzymes. L-Alloisocitrate induces both enzymes in the growing pseudomonad.

Alcohol Oxidoreductases↗
PubMed1980

Human leukocyte antigen (HLA) in patients with idiopathic portal hypertension (IPH).

Both cryptogenic liver cirrhosis and idiopathic portal hypertension without pathological findings of liver cirrhosis (IPH) are relatively common in Japan. To find differrence between IPH and cryptogenic liver cirrhosis of Japanese, we investigated human leukocyte antigen (HLA), familial clustering of liver diseases as well as prevalence of HBs antigen in 31 patients with IPH. The age of patients with IPH ranged between 6 and 67 years old (mean, 40 years). The ratio of female to male in patients with IPH was 3.1. The incidence of chronic liver diseases in the relatives of patients with cryptogenic liver cirrhosis was significantly high (29.1%), whereas that in the relatives of patients with IPH was not high (12.9%) as compared with hospitalized controls (8.9%). The phenotype frequencies of the specificities of HLA A and B loci in patients with IPH did not differ from those in healthy controls. And the incidence of HBs antigen and antibody in patient with IPH (3.2% and 20.7%, respectively) was similar to those in normal subjects in Japan. These findings suggest that IPH in Japan is a different clinical entity from cryptogenic liver cirrhosis and that HB virus may not be one of the main causes of IPH.

Adolescent↗
PubMed1978

Proton correlation nuclear magnetic resonance study of anaerobic metabolism of Escherichia coli.

Proton correlation nuclear magnetic resonance has been used to investigate anaerobic metabolism of glucose in Escherichia coli cells. The time course of the concentrations of six metabolites (ethanol, lactate, acetate, pyruvate, succinate, and formate) has been followed at the very early state of fermentation, and used to discuss dynamical aspects of the mixed-acid fermentation of glucose by E. coli.

Anaerobiosis↗