Mouse {beta}-galactoside {alpha}2,3-sialyltransferases: comparison of in vitro substrate specificities and tissue specific expression

Four types of ß-galactoside     

In vitro microsome-mediated aflatoxin B1-DNA binding and its inhibition by cytosol of various organs of the hamster and quail

We studied thein vitro activation of aflatoxin B1 (B1) by microsomes and its inactivation by the cytosol of various quail and hamster organs, using B1-DNA binding as an index. The microsomal activity of the liver to bind B1 to DNA was not largely different between the two species and was higher than that of the other organs examined in either species. The microsomal activity of the kidney and lung was very low in the quail compared with the hamster, indicating the very small contribution of the lung and kidney microsomes to the activation of B1 in birds. Only the hamster liver cytosol showed strong inhibition of microsome-mediated B1-DNA binding.     

Alcohol and aldehyde dehydrogenase genotypes and drinking behavior of Chinese living in Shanghai

Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH), the principal enzymes responsible for oxidative metabolism of ethanol, exist in multiple, genetically determined molecular forms. Widely different kinetic properties in some of these isozymes account for the individual differences in alcohol sensitivity. In this study we used the polymerase chain reaction/restriction fragment length polymorphism method to determine the genotypes of the ADH2 and ALDH2 loci of alcoholic and nonalcoholic Chinese living in Shanghai. We also investigated the subjects' drinking patterns by means of semistructured interviews. The alcoholics had significantly lower frequencies of the ADH2² and ALDH2² alleles than did the nonalcoholics, suggesting the inhibitory effects of these alleles for the development of alcoholism. In the nonalcoholic subjects, ADH2² had little, if any, effect, despite the significant effect of the ALDH2² allele in decreasing the alcohol consumption of the individual. Taken together, these results fit the proposed hypothesis for the development of alcoholism, i.e., drinking behavior is greatly influenced by the individual's gentoypes of alcohol-metabolizing enzymes, and the risk of becoming alcoholic is proportionate with the ethanol consumption of the individual.     

Partial characterization of the glucose transport activity in the golgi-rich fraction of fat cells

The glucose transport activity solubilized from the basal and plus insulin forms of the Golgi-rich fraction of adipocytes was partially characterized, and the results were compared with those of the activity obtained from the plus insulin form of the plasma membrane-rich fraction. The transport activity was determined in a cell-free, reconstituted, system. Prior to reconstitution, the activities in the three preparations were all (a) stable at 0°C for at least 4 h, but not at 37°C or above; (b) most stable at pH 7–9, and (c) less stable in Tes than in Tris buffer. After reconstitution, the three activities were all (d) stable at 0°C, (e) most active at pH 5.5, (f) mildly stimulated by divalent cations, (g) unaffected by insulin or 1 mM of several SH-blocking agents, (h) inhibited by heavy metal ions, 10–100 mM of monovalent salts, organic solvents, several sugar isomers, and specific sugar-transport inhibitors. The rates of d-glucose uptake by the three liposome preparations were all inhibited more strongly by 2-deoxy-d-glucose or $\text{3}\text{-O-}\text{methyl-}\text{d}\text{-glucose}$ than by d-glucose. These data indicate that the general properties of the glucose transport activity in the Golgi-rich fraction are similar to those of the activity in the plasma membrane-rich fraction.     

Oxygen Enhancement of bactericidal activity of rifamycin SV on Escherichia coli and aerobic oxidation of rifamycin SV to rifamycin S catalyzed by manganous ions: the role of superoxide

Oxygen enhanced the bactericidal activity of rifamycin SV to Escherichia coli K12. Anaerobically grown cells, which had a low level of superoxide dismutase, were more susceptible to the bactericidal activity than aerobically grown cells, which contained a high level of superoxide dismutase. Oxygen also enhanced the inhibition of RNA polymerase activity of rifamycin SV, when Mn2+ was used as a cofactor. Rifamycin S was reduced to rifamycin SV by NADPH catalyzed by cell-free extracts of Escherichia coli K12. These results indicate that the inhibition of bacterial growth by rifamycin SV is due to the production of active species of oxygen resulting from the oxidation-reduction cycle of rifamycin SV in the cells. The aerobic oxidation of rifamycin SV to rifamycin S was induced by metal ions, such as Mn2+, Cu2+, and Co2+. The most effective metal ion was Mn2+. In the presence of Mn2+, accompanying the consumption of 1 mol of oxygen and the oxidation of 1 mol of rifamycin SV, 1 mol of hydrogen peroxide and 1 mol of rifamycin S were formed. Superoxide was generated during the autoxidation of rifamycin SV. Superoxide dismutase inhibited the formation of rifamycin S, but scavengers for hydrogen peroxide and the hydroxyl radical did not affect the oxidation. A mechanism of Mn2+-catalyzed oxidation of rifamycin SV is proposed and its relation to bactericidal activity is discussed.     

Corn leaf glutamate synthase: Purification and properties of the enzyme

An assay for ferredoxin-glutamate synthase is introduced thatuses an anion exchange resin to isolate the glutamate formedand subsequent determination with the ninhydrin procedure. Theenzyme was purified 200-fold from corn leaves by ammonium sulfatefractionation and chromatography on DEAE-cellulose, DEAE-Sephaceland ferredoxin- Sepharose. The purified enzyme had a specificactivity of 14 µmoles glutamate formed min^–1mg^–1protein. The enzyme has a molecular weight of 160,000. The pHoptimum for catalytic activity is 6.9. The isoelectric pointis at pH 4.2. The apparent Km values of the enzyme for L-glutamine,2-oxoglutarate and ferredoxin are 1,100, 240 and 1.7 µM.The enzyme has a high specificity toward these substrates witha stoichiometry between glutamate formation and glutamine consumption.Sulfhydryl reagents, bathophenanthroline, phthalein acids andazaserine produced strong inhibition of the enzyme activity. ¹Permanent address: Department of Agricultural Chemistry, KyotoUniversity, Kyoto 606, Japan. ²To whom inquiries should be addressed. (Received July 7, 1979; )     

Pili mediated agglutination of Serratia marcescens in human urine

Of 51 strains of Serratia marcescens isolated from patients with urinary or respiratory tract infections, 35 agglutinated in human urine. The agglutinating strains possessed numerous pili which were morphologically distinct from common pili or type I pili. The diameter of the pili was 3 nm and the average length was 0.3 micrometer. Electron microscopic examination showed that 80% or more of the cells of the agglutinating strains and 0 to 8% of the cells of the nonagglutinating strains were piliated. When an agglutinating strain was heated at 55 C for 10 min, it lost its agglutinating capacity and concomitantly its pili. These results suggest that the agglutination might occur because of interactions between the pili and some factors in human urine. The urinary slime appears to contain these agglutinating factors.     

Elimination of insulin-like activity present in certain batches of crude bovine serum albumin by trypsin treatment

A comparative study was carried out in order to determine which of the most commonly used alkalies for protein hydrolysis in tryptophan determination gave the best results. Hydrolyses were performed with 2.5 and 4 n Ba (OH)₂, 4 and 10 n NaOH, 5 n NaOH containing 5% SnCl₂, and with 4 n LiOH, not previously reported for use. The effect of temperature and hydrolysis time on the measured tryptophan content was also determined. Based on results obtained with lysozyme and with seven high protein preparations 4 n LiOH gave the best results. A temperature of 145°C was selected as the most convenient temperature since maximum tryptophan values were obtained with 4–8 h. The hydrolysis time required was inversely related to the protein content of the preparation. Lysozyme, casein, bovine plasma protein, and dehydrated whole egg gave maximum tryptophan content after 4 h hydrolysis while skimmed milk powder, rice flour, wheat flour, and wild legume flour required 8 h hydrolysis.