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Biomedical subjects

S Fukui

Publications and source records attributed to S Fukui.

At least 289 records · Page 16Linked to original sources
PubMed1978

Subcellular localization of two long-chain acyl-coenzyme-A synthetases in Candida lipolytica.

Studies have been made on the subcellular localization of two long-chain acyl-coenzyme-A synthetases as well as glycerolphosphate acyltransferase and the acyl-CoA-oxidizing system in Candida lipolytica grown on oleic acid. Acyl-CoA synthetase I is distributed among different subcellular fractions, including microsomes and mitochondria where glycerolphosphate acyltransferase is located. On the other hand, acyl-CoA synthetase II is localized in microbodies where the acyl-CoA-oxidizing system is located. These results support our previous conclusion that acyl-CoA synthetase I is responsible for the production of acyl-CoA to be utilized for the synthesis of cellular lipids, while acyl-CoA synthetase II provides acyl-CoA that is exclusively degraded via beta-oxidation.

Candida↗
PubMed1978

Fatty acid beta-oxidation system in microbodies of n-alkane-grown Candida tropicalis.

Localization of fatty acid beta-oxidation system in microbodies of Candida tropicalis cells growing on n-alkanes was studied. Microbodies isolated from the yeast cells showed palmitate-dependent activities of NAD reduction, acetyl-CoA formation and oxygen consumption. When sodium azide, an inhibitor of catalase, was added to the system, palmitate-dependent formation of hydrogen peroxide was observed. Stoichiometric study revealed that two moles of NAD were reduced per one mole of oxygen consumed in the absence of sodium azide and the presence of the inhibitor doubled the oxygen consumption by microbodies without an appreciable change in NAD reduction. These results indicate that the yeast microbodies contain beta-oxidation system of fatty acid, and that catalase located in the organelles participates in the degradation of hydrogen peroxide to be formed at the step of dehydrogenation of acyl-CoA.

Acetyl Coenzyme A↗
PubMed1978

Immunological determination of serum m-AST activity in patients with acute myocardial infarction.

Serum m-AST (mitochondrial isoenzyme of AST) activity in patients with acute myocardial infarction was determined quantitatively by a new immunological technique which is sensitive and easily available. All 31 patients with acute myocardial infarction showed abnormally high levels of serum m-AST (more than 5 KU/ml); the mean serum m-AST activity attained its peak (42.0 +/- 4.9 KU/ml) on the first day after the onset of infarction 5 hours later than that of serum t-AST (total AST) activity in 15 patients whose peak m- and t-AST activities were identified clearly. The individual peak m-AST activity correlated with the total CK released (r = 0.83, n = 15), indicating that the release of m-AST also reflects the infarct size. The ratio of serum m-AST/t-AST increased following myocardial infarction and showed the maximal value (average 25.7%) on the third to seventh day after onset. This ratio in the patients with acute myocardial ifarction was also greater than that in patients with liver disease or with heart failure from causes other than acute myocardial infarction. In the patients who had the additional complication of heart failure and/or cardiogenic shock the ratio was also greater than that is the patients without these hazards. These results indicate that the ratio of serum m-AST/t-AST reflects the severity of the myocardial cellular damage in acute myocardial infarction.

Acute Disease↗
PubMed1977

Effect of chemical modification of cell surface components of a brewer's yeast on the floc-forming ability.

Effects of treatments with proteolytic enzymes and protein-modifying reagents on flocculation of brewer's yeast IFO 2018 were investigated. The floc-forming ability of the yeast cells was irreversibly eliminated by treatment with papain, trypsin, chymotrypsin or pepsin, indicating that certain proteins on the cell surface participate in the yeast flocculation. Chemical modification with reagents, known to act on disulfide bridges, carboxyl and/or phosphate groups, phenolic groups, amino groups, and imidazole groups, also destroyed the ability to flocculate, although in some cases a high concentration (8 M) of urea was necessary in addition to protein-modifying reagents. Thus, it is suggested strongly that these functional groups of amino acid residues of the proteins are essential for the floc-forming ability of brewer's yeast cells.

Cell Wall↗
PubMed1977

Immobilization of yeast microbodies by inclusion with photo-crosslinkable resins.

Yeast microbodies containing FAD-dependent alcohol oxidase, catalase and D-amino acid oxidase were isolated from methanol-grown cells of Kloeckera sp. 2201 and immobilized intact in matrices formed by a short-time illumination of photo-crosslinkable resin oligomers. The relative activities of catalase, alcohol oxidase and D-amino acid oxidase of the gel-entrapped microbodies were 36, 76 and 31% respectively as compared with those of free microbodies. Immobilization enhance d the stability of catalase to a certain degree, but not that of alcohol oxidase. The pH/activity profiles of catalase and alcohol oxidase of the entrapped organelles showed more narrow pH optima than those of the free counterparts. D-Amino acid oxidase in immobilized microbodies showed a somewhat higher Km value for D-alanine than that in free ones. Immobilized microbodies oxidized two moles of methanol to form two moles of formaldehyde with consumption of one mole of molecular oxygen. Addition of 3-amino-1,2,4-triazole, an inhibitor of catalase, reduced the formation of formaldehyde to half the amount without change in the amount of oxygen consumed, indicating the synergic action of alcohol oxidase and catalase in methanol oxidation in the microbodies of living yeast cells.

Alcohol Oxidoreductases↗
PubMed1977

Immunochemical evidence for the difference between coenzyme-B12-dependent diol dehydratase and glycerol dehydratase.

Klebsiella pneumoniae ATCC 25955 (formerly named Aerobacter aerogenes PZH 572, Warsaw), which is known to produce coenzyme-B12-dependent glycerol dehydratase when grown anaerobically in a glycerol medium, formed coenzyme-B12-dependent diol dehydratase in a 1,2-propanediol-containing medium. Both the diol dehydratase and the glycerol dehydratase produced by the organism catalyzed the conversion of glycerol, 1,2-propanediol and 1,2-ethanediol to the corresponding aldehydes and underwent concomitant inactivation during the catalysis of glycerol dehydration, as does the diol dehydratase of K. pneumoniae (A. aerogenes) ATCC 8724. However, the two enzymes were distinguishable from each other by the monovalent-cation-selectivity pattern and by substrate specificity; that is, glycerol dehydratase preferred glycerol to 1,2-propanediol as a substrate, whereas diol dehydratase preferred 1,2-propanediol to glycerol, as judged from initial velocity studies. Ouchterlony double-diffusion analysis and immunochemical titration with rabbit antiserum against diol dehydratase of K. pneumoniae ATCC 8724 established clearly that the diol dehydratase of K. pneumoniae ATCC 25955 is immunologically similar to that of K. pneumoniae ATCC 8724, while the glycerol dehydratase of the former is different from the diol dehydratase of both strains. Both the enzymes were found to be distributed in several bacteria of the family Enterobacteriaceae.

Cations, Monovalent↗
PubMed1977

Effects of thiamine and pyridoxine on the lipid composition of Saccharomyces carlsbergensis 4228.

The lipid composition of Saccharomyces carlsbergensis 4228 cells grown aerobically in the presence of thiamine and absence of pyridoxine was markedly different from that of cells grown without addition of both of the growth factors. In addition to the previous observations showing a reduction in the levels of unsaturated fatty acids (Nishikawa, Y., Nakamura, I., Kamihara, T. and Fukui, S. (1974) Biochem. Biophys. Res. Commun. 59, 777-780) and lack of zymosterol and ergosterol (Nagai, J., Katsuki, H., Nishikawa, Y., Nakamura, I., Kamihara, T. and Fukui, S. (1974) Biochem. Biophys. Res. Commun. 60, 555-560), the thiamine-grown cells were found to contain low levels of total lipids, sterols (especially in the form of esters), triacylglycerols and total phospholipids. However, relative contents of triacylglycerols and phospholipids to total lipids were higher than those of control cells. Hydrocarbons and diacylglycerols accumulated to appreciable degrees. Phospholipid composition was also influenced by thiamine. The ratio of phosphatidylinositol to total phospholipids increased, whereas that of phosphatidylethanolamine decreased. The levels of phosphatidylcholine plus phosphatidylserine decreased in a similar ratio to that of total phospholipids. It was found that unsaturated fatty acid contents were low in all lipid esters tested. The effect of thiamine was particularly noteworthy in the case of sterol esters. Concomitant addition of pyridoxine with thiamine to the medium brought about a normal lipid composition in the yeast cells.

Diglycerides↗
PubMed1977

Studies on the mechanism of the adenosylcobalamin-dependent diol dehydrase reaction by the use of analogs of the coenzyme.

A series of 16 analogs of 5'-deoxy-5'-adenosylcobalamin (adenosylcobalamin) were examined for their effects on the diol dehydrase system of Klebsiella pneumoniae (Aerobacter Aerogenes). Four analogs, ara-adenosyl-, aristeromycyl-, 3-isoadenosyl-, and nebularylcobalamin, were able to function as coenzymes in the diol dehydrase reaction, coenzyme activity decreasing in that order. Like the native holoenzyme, complexes of the enzyme with these four analogs show a cob(II)alamin-like absorption peak or shoulder in the presence of 1,2-propanediol. Analogs containing hypoxanthine, cytosine, or benzimidazole do not function as coenzymes, but are weak competitive inhibitors in the presence of adenosylcobalamin. Analogs in which the D-ribosyl moiety is replaced by L-ribose or by an alkyl chain of 2 to 6 carbons are inactive as coenzymes, but act as competitive inhibitors with extremely high affinity for the apoenzyme. Complexes with the inactive analogs showed visible spectra similar to those of the corresponding free cobalamins. Upon anaerobic photolysis and subsequent aeration, complexes with the first group of inactive analogs produced unusually stabilized cob(II)alamin, while complexes with the second group of inactive analogs were readily photolyzed to a hydroxocobalamin-enzyme complex. Complexes with adeninylpentyl- and L-adenosylcobalamin were stable to light under the same conditions. These findings suggest that both the ribose and the adenine moiety of the nucleoside participate in enzyme-coenzyme interaction, involving not only the binding to the apoenzyme but also the activation of the carbon-cobalt bond.

Apoenzymes↗
PubMed1977

Glucose-phosphorylating enzymes of Candida yeasts and their regulation in vivo.

Three glucose-phosphorylating enzymes having different specificities for glucose and fructose were separated from the cell-free extract of Candida tropicalis by means of ammonium sulfate fractionation and chromatography on DEAE-cellulose and Sephadex G-100. Two of them, which phosphorylated fructose 1.5 times faster than glucose, were designated as hexokinase I and II (ATP : D-hexose 6-phosphotransferase, EC 2.7.1.1.), and the other with very low or no fructose-phosphorylating activity, as glucokinase (ATP : D-glucose 6-phosphotransferase, EC 2.7.1.2). Km values for glucose with both hexokinase I and glucokinase were 0.3 mM, and that for fructose with hexokinase I was 2.2 mM. Time-course changes in the levels of these enzymes in C. tropicalis growing on glucose and on n-alkane revealed that hexokinase was induced specifically by the sugars, while glucokinase was a constitutive enzyme. Addition of cycloheximide to the culture medium prevented the increase in the hexose-phosphorylating activity and in the Fru/Glu ratio (the ratio of enzymatic phosphorylation of fructose to that of glucose) in the cells. Although Candida lipolytica also contained hexokinase and glucokinase, both enzymes seemed to be constitutive.

Acetates↗
PubMed1977

Microbody of n-alkane-grown yeast. Enzyme localization in the isolated microbody.

Microbodies appearing abundantly in n-alkane-grown cells of Candida tropicalis pK 233 were isolated by means of sucrose density gradient centrifugation. Electron microscopical observation showed that the microbodies isolated were intact. Localization of catalase and D-amino acid oxidase in the isolated microbodies was confirmed. Isocitrate lyase, melate synthase and NADP-linked isocitrate dehydrogenase were also located in the microbody, but malate dehydrogenase, citrate synthase, aconitase and NAD-linked isocitrate dehydrogenase were not. Neither cytochrome P-450 not NADPH-cytochrome c reductase, the components involved in the n-alkane hydroxylation system of the yeast, were detected in the microbody fraction.

Alkanes↗
PubMed1977

Rapid induction of alpha-amylase by nongrowing mycelia of Aspergillus oryzae.

A rapid induction system for synthesis of alpha-amylase by the funga Aspergillus oryzae M-13 was established. The mycelia were prepared from 20-h cultures grown on a peptone-glycerol medium and starved for 5 h; maltose was the optimum inducer tested. During h 1 of induction, formation of both intra- and extracellular alpha-amylases occurred at an almost identical rate (70 to 80 microgram/g of cells-h) without a detectable lag period. After a 1-h induction period, a remarkable increase in the extracellular concentration of the enzyme occurred, and a maximum rate (330 microgram/g of cells-h) was reached after 1.5 h of induction. During h 2 of induction, no significant change in mycelial weight was observed. Purified samples of intra- and extracellular enzymes formed in the induction system showed identical properties as examined by behavior in diethylaminoethyl-cellulose column chromatography, gel filtration, discontinuous gel electrophoresis, electrofocusing, optimal conditions for the reaction, heat stability, and molecular weight.

Amylases↗
PubMed1977

Production of uricase by Candida tropicalis using n-alkane as a substrate.

Production of uricase (urate oxidase, EC 1.7.3.3) by n-alkane-utilizing Candida tropicalis pK233 was studied. Although the yeast showed very low enzyme productivity under growing conditions on glucose or an n-alkane mixture (C10 to C13) (less than 2 U/g of dry cells), enzyme formation was enhanced markedly in an induction medium consisting of potassium phosphate buffer, MgSO4, uric acid, and an n-alkane mixture (47 U/g of dry cells) or glucose (21 U/g of dry cells). Of the carbon sources tested, the n-alkane mixture was the most suitable for enzyme production. Appropriate aeration also stimulated uricase formation. In addition to uric acid, xanthine, guanine, adenine, and hypoxanthine were also effective for inducing uricase. Under optimum conditions, the maximum yield of the enzyme was 91 U/g of dry cells. Uricase thus induced was localized in the microbodies of the yeast.

Alkanes↗
PubMed1977

Evaluation of evolution of myocardial infarction by serial determinations of serum creatine kinase activity.

In order to investigate the relation between the release of creatine kinase (CK) in acute myocardial infarction and the evolution of infarction, the appearance functions of CK (release of CK from the heart into the circulation) were calculated by the modified method of Sobel and associates from the serial determinations of serum CK activity in 50 patients with acute myocardial infarction. The relation of the time between the onset of infarction and the peak value of the appearance function to the duration of the evolution of abnormal Q waves in 14 patients with inferior infarction and to the duration of pain in all patients was investigated. The duration of CK release from the heart averaged 37-2+/-2-4 hours and correlated well with the total CK released (R=0.665) which represents the infarct size. The mean per cent of the total CK eventually released by the time of maximum sigmaQ (sum of the amplitude of Q wave in leads II, III, and aVF) was 80-0+/-6-4 per cent and that of CK released while pain persisted was 72-0+/-3-9 per cent. These results strongly suggest that the appearance function of CK reflects the evolution of myocardial infarction.

Adult↗