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Biomedical subjects

S Fukui

Publications and source records attributed to S Fukui.

At least 235 records · Page 13Linked to original sources
PubMed1983

Comparison of sulfation of glycosaminoglycans and glycopeptides from control and virus-transformed baby hamster kidney cells.

Sulfation of glycosaminoglycans and glycopeptides was compared in baby hamster kidney (BHK) cells and the polyoma virus transformants (PY-BHK). Cells were incubated with [3H]glucosamine and [35S]sulfate, and the labeled glycosaminoglycans and glycopeptides were isolated by digesting the cell membrane fraction with pronase followed by gel filtration. Each type of glycosaminoglycan in the void volume fraction (Fraction I) and in the included fraction (Fraction II) was determined by sequential enzymatic digestions. The residue was regarded as being glycopeptides. Of the total 3H radioactivities of glycosaminoglycans in Fraction I from BHK cells, 51% were in dermatan sulfate, 23% were in heparan sulfate, 17% were in chondroitin 4- and 6-sulfates, and 9% were in hyaluronate. PY-BHK cells acquired significantly larger amounts of 3H radioactivities in sulfated glycosaminoglycans than did BHK cells on the basis of cell number. On the basis of protein content, there was no such difference due to higher protein content of PY-BHK cells. The degree of sulfation of the glycosaminoglycans, estimated from the ratio of 35S to 3H and by disaccharide analysis, was significantly lower in PY-BHK cells than in BHK cells. Considerable amounts of 35S radioactivities assigned to sulfated glycopeptides were found in Fraction II from both BHK and PY-BHK cells.

Animals↗
PubMed1983

High performance liquid chromatographic determination of malondialdehyde in vegetable oils.

A simple high performance liquid chromatographic (HPLC) method has been developed for determining malondialdehyde (MDA) in vegetable oils. MDA was reacted with dansyl hydrazine in an acidic medium, and the product, 1-dansyl-pyrazole, was determined by HPLC, using a Zorbax sil column with mixed mobile phase of n-hexane-methylene chloride. MDA can be determined as 1-dansyl-pyrazole by fluorometric detection at a level of 0.01 ppm in vegetable oils.

Chromatography, High Pressure Liquid↗
PubMed1982

Cell-free translation and regulation of Candida tropicalis catalase messenger RNA.

To gain information on metabolic control and peroxisome biogenesis in Candida tropicalis growing on n-alkanes, cell-free translation of catalase (H2O2:H2O2 oxidoreductase, EC 1.11.1.6), a general marker enzyme of peroxisomes, was performed. The level of catalase activity in alkane-grown cells was approximately 9-fold and 27-fold higher than that in ethanol-grown and glucose-grown cells, respectively. Immunochemical titration experiments with rabbit antiserum against the purified peroxisomal catalase from alkane-grown C. tropicalis indicated that the remarkable variation in the enzyme activity level on different carbon sources was ascribable to a corresponding change in the amount of the enzyme protein. When cell-free translation was carried out with the mRNA-dependent reticulocyte lysate system, total RNA prepared from alkane-grown cells was shown to direct the synthesis of catalase subunit in vitro. The identity of the cell-free translation product was ascertained by the following evidence: (a) the translation product was immuno-reactive with specific antibody to catalase and competed effectively with the authentic enzyme for immunoprecipitation; (b) it possessed a molecular weight indistinguishable from that of authentic catalase subunit (Mr 54000); (c) its peptide fragments formed by partial digestion with Staphylococcus aureus V8 protease were identical with those from the authentic enzyme. With the use of the cell-free translation system, it was indicated that the significant change in the amount of catalase protein on different carbon sources nearly paralleled that in the activity of the mRNA encoding the enzyme.

Alkanes↗
PubMed1982

Peroxisomal and mitochondrial carnitine acetyltransferases in alkane-grown yeast Candida tropicalis.

Two types of carnitine acetyltransferases (EC 2.3.1.7) were first isolated from a microorganism, alkane-grown yeast Candida tropicalis. Carnitine acetyltransferase activity was induced in the alkane-grown cells, reaching about twenty times higher than that in the glucose-grown cells. Localization of the enzyme activity was demonstrated, at least, in peroxisomes (microbodies), profusely occurred in the alkane-grown cells, and in mitochondria. Peroxisomal and mitochondrial carnitine acetyltransferases could be separated using the method of DEAE-Sephacel column chromatography and both types were found to exist in the alkane-grown cells of C. tropicalis. Each carnitine acetyltransferase was purified using Sephadex G-200, Sepharose 6B, DEAE-Sephacel and Blue-Sepharose CL-6B. In DEAE-Sephacel chromatography, peroxisomal carnitine acetyltransferase was eluted below 0.15 M KCl concentration and mitochondrial carnitine acetyltransferase above 0.15 M KCl concentration. Except for the localization, little difference was observed in their kinetic properties, substrate specificity and so on. These two carnitine acetyltransferase preparations were only specific to acetyl and propionyl groups, the substrate specificity not being so broad as that of carnitine acetyltransferase obtained from mammalian tissues. Roles of these carnitine acetyltransferases in alkane metabolism in yeast are also discussed.

Acetyltransferases↗
PubMed1982

Properties of catalase purified from whole cells and peroxisomes of n-alkane-grown Candida tropicalis.

Peroxisomes appear profusely, in harmony with a marked enhancement of catalase activity level, in yeast cells growing on n-alkanes or higher fatty acids as the sole carbon source. Catalase (H2O2:H2O2 oxidoreductase, EC 1.11.1.6) was purified to homogeneity from the crude extract and from the peroxisome-containing particulate fraction of alkane-grown Candida tropicalis cells. The purified enzyme from each source was a similar protein of molecular weight 210000 composed of four identical subunits of molecular weight 54000, namely a kind of homotetramer. The enzyme contained one molecule of heme per subunit, giving the absorption spectrum characteristic of hemoprotein. Beta-(3,4-Dihydroxyphenyl)-L-alanine served as a substrate for the peroxidatic reaction by the enzyme. Ouchterlony double-diffusion analysis and immunochemical titration with rabbit antiserum against peroxisomal catalase of n-alkane-grown C. tropicalis have indicated that cytoplasmic catalase of the yeast is immunologically indistinguishable with peroxisomal catalase.

Alkanes↗
PubMed1982

Role of metabolism of the mating pheromone in sexual differentiation of the heterobasidiomycete Rhodosporidium toruloides.

A trypsin-type endopeptidase (Kamiya et al., Biochem. Biophys. Res. Commun. 94:855-860, 1980) responsible for the metabolism of rhodotorucine A, the farnesyl undecapeptide mating pheromone secreted by mating type A cells of Rhodosporidium toruloides, was biologically characterized. Metabolic activity was found to be present exclusively on the cell surface of the pheromone target cell. The activity was highly specific to the pheromone, and a biologically inactive analog which has the complete amino acid sequence of rhodotorucine A but lacks the farnesyl residue was not metabolized by intact cells. Pheromone metabolism was inhibited by trypsin substrates such as tosyl-L-arginine methyl ester. The presence of tosyl-L-arginine methyl ester strongly inhibited the sexual differentiation induced by the pheromone at a concentration which did not affect the vegetative growth of R. toruloides. Pheromone-induced sexual differentiation was also strongly inhibited by a metabolizable analog, rhodotorucine A S-oxide, but not by a non-metabolizable one. In mutants defective in early processes of mating, the decrease in the pheromone metabolic activity correlated well with the extent of loss of sensitivity to the pheromone. Both the pheromone metabolism and the capacity for sexual differentiation of a sterile mutant were restored concomitantly with reversion from the sterile to the fertile phenotype. These results suggested that metabolism of the mating pheromone plays an essential role in the process of sexual differentiation in R. toruloides.

Basidiomycota↗
PubMed1982

Clinical evaluation of left ventricular performance in patients with myocardial infarction: comparison of hemodynamic responses to exercise and angiographic findings.

In order to evaluate the left ventricular performance during exercise in patients with myocardial infarction, we performed a symptom-limited multistage exercise test using a bicycle ergometer in the supine position on 82 patients with myocardial infarction, and their hemodynamic responses to exercise were analyzed. Patients were subdivided into three groups according to the levels of pulmonary capillary wedge pressure (PCWP) and cardiac index (CI) obtained at the end-point of the exercise: Group I (20 patients) with PCWP less than 18 mmHg and CI greater than or equal to 5.0 L/min/m2; Group II (32 patients) with PCWP greater than or equal to 18 mmHg and CI greater than or equal to 5.0 L/min/m2; Group III (30 patients) with PCWP greater than or equal to 18 mmHg and CI less than 5.0 L/min/m2. Exercise tolerance expressed as the duration of exercise was 11.9 +/- 0.5 (SEM) min in Group I, 10.6 +/- 0.4 in Group II and 7.8 +/- 0.5 in Group III, which was closely correlated with the left ventricular function observed at the end-point of the exercise. During exercise stroke volume index (SVI) decreased slightly in Group III, while it increased significantly in Groups I and II. The extent of coronary artery lesion in Group III was more severe than in Groups I and II. In 50 patients without prior myocardial infarction, infarct size estimated by total released CPK was larger in Group III than in Group I. These findings indicate that coronary artery lesion and infarct size are important factors contributing to left ventricular performance during exercise in patients with myocardial infarction.

Adult↗
PubMed1982

Clinical evaluation of left ventricular function in acute myocardial infarction--analysis of factors affecting left ventricular function.

The clinical significance of the possible factors which may affect the cardiac function and prognosis of the patients with acute myocardial infarction were evaluated in 112 patients with this disease. Patients were subdivided into 4 groups according to the levels of pulmonary capillary wedge pressure (PCWP) and left ventricular stroke work index (SWI): Group I (52 patients) PCWP less than 18 mmHg, SWI less than or equal to 30 g.m/m2; Group II (18 patients) PCWP greater than or equal to 18 mmHg, SWI greater than or equal to 30 g.m/m2; Group III (15 patients) PCWP less than 18 mmHg, SWI less than 30 g.m/m2; Group IV (27 patients) PCWP greater than or equal to 18 mmHg, SWI less than 30 g.m/m2. Immediate mortality rate (4 weeks after the onset of myocardial infarction) was 17.0% in all patients and Group IV had the highest mortality rate (48.1%), in contrast to the lowest mortality rate (3.8%) in Group I. The episodes of previous myocardial infarction were noted more frequently in Group IV (74.1%) than in Groups I (7.7%) and II (11.1%) (p less than 0.001). Mean age in Group IV (68.0 +/- 5.2 (SE) years) was also significantly higher than those of the remaining 3 groups (p less than 0.001). In 55 patients without previous myocardial infarction, mean infarct size estimated from total released creatine phosphokinase (CPK) (sigma CPK) in Group IV was largest among the 4 groups, although it was similar to that in Group II: 919.0 +/- 70.0 (SE) IU/ml in Group I, 1470.0 +/- 126.0 in Group II, 958.0 +/- 107.0 in Group III and 1493.0 +/- 145.0 in Group IV. The number of involved coronary arteries differed significantly between Groups I and IV: in Group I involved coronary artery (75% narrowing) was absent or one at most, while in Group IV all 9 patients had at least one coronary lesion and 3 of 9 had triple vessel disease. In this study no significant difference was observed between the incidence of anterior and inferior myocardial infarctions in Groups I, III and IV. Thus, we conclude that age, previous myocardial infarction, infarct size and the number of involved coronary arteries may determine the cardiac function in acute phase of myocardial infarction and hence, immediate mortality of this disease.

Adult↗
PubMed1982

The mechanism of in sutu reactivation of glycerol-inactivated coenzyme B12-dependent enzymes, glycerol dehydratase and diol dehydratase.

In the previous paper (S. Honda, T. Toraya, and S. Fukui, J. Bacteriol., 143, 1458-1465 (1980)), we reported that the glycerol-inactivated holoenzymes of adenosylcobalamin-dependent glycerol dehydratase and diol dehydratase are rapidly and continually reactivated in toluene-treated cells (in situ) by adenosine 5'-triphosphate (ATP) and divalent metal ions in the presence of free adenosylcobalamin. To elucidate the mechanism of this in situ reactivation, the nature of the binding of various irreversible cobalamin inhibitors to the dehydratases in situ was investigated. In the presence of ATP and Mn2+, enzyme-bound hydroxocobalamin, cyanocobalamin and methylcobalamin were rapidly displaced by added adenosylcobalamin. Without ATP and Mn2+, such displacement did not take place. In contrast, enzyme-bound adeninylbutylcobalamin and adenosylethylcobalamin were essentially not displaceable by the free coenzyme even in the presence of ATP and Mn2+. Inosylcobalamin was a very weak inhibitor irrespective of the presence of ATP and Mn2+. These results indicate that the relative affinity of the enzymes in situ for the cobalamins with simple Co beta ligands was markedly lowered in the presence of ATP and Mn2+, whereas that for the cobalamins with adenine-containing ligands was not. When the glycerol-inactivated holoenzymes in situ were dialyzed against a buffer containing ATP and Mg2+, the inactivated coenzyme moiety dissociated from the enzymes leaving apoproteins. Kinetic evidence was also obtained with the dehydratases in situ that continual displacement of the inactivated coenzyme moiety by adenosylcobalamin takes place during the glycerol dehydration reaction in the presence of ATP and Mn2+. Since the adenosyl group of the bound coenzyme is irreversibly removed from the cobalamin moiety during inactivation by glycerol, all of these data constitute clear evidence that the inactivated holo-dehydratases are reactivated in situ in the presence of ATP and Mn2+ by displacement of the modified coenzyme moiety by free intact adenosylcobalamin (i.e. selective B12-exchange mechanism).

Adenosine Triphosphate↗
PubMed1981

Glycosaminoglycan synthesis by cultured skin fibroblasts from a patient with Lowe's syndrome.

Glycosaminoglycan metabolism in cultured skin fibroblasts from a patient with Lowe's syndrome (oculocerebrorenal syndrome) was compared with that in normal fibroblasts. Cells were incubated with [3H]glucosamine and 35SO42-, and then the labeled glycosaminoglycans in the medium, trypsinate, and cell membrane fractions were analyzed by means of enzymatic and chemical degradations and by electrophoresis. Glycosaminoglycans, mostly chondroitin sulfates and dermatan sulfate, were markedly undersulfated in Lowe's syndrome. Undersulfation was most pronounced in the cell membrane fraction of cells which had been incubated at 0.03 mM sulfate concentration. Even at 0.52 mM or a higher sulfate concentration, undersulfation of chondroitin sulfates in the cell membrane fractions was significant. The undersulfation was the result of depressed sulfation rather than that of increased desulfation, as demonstrated by pulse-chase experiments using 35SO42-. Hyaluronate synthesis was not significantly impaired in the Lowe's syndrome fibroblasts. It was inferred, based on the results of the present study and those previously reported that the undersulfation of glycosaminoglycans is a consequence of a lower level of active sulfate (adenosine 3'-phosphate 5'-phosphosulfate) in the Lowe's syndrome fibroblasts, caused by an elevation of nucleotide pyrophosphatase activity degrading adenosine 3'-phosphate 5'-phosphosulfate.

Cell Division↗