| 摘要 |
A microorganism strain B-0781 belonging to the genus Pseudomonas isolated from a soil sample from an onion field in Japan, produces a novel enzyme nucleoside oxidase having substrate specificity on various nucleosides and enzyme action to catalyze enzymatic reactions involving various nucleosides. The novel nucleoside oxidase is produced by culturing a nucleoside-oxidase-producing microorganism belonging to the genus Pseudomonas in a nutrient medium containing assimilable carbon and nitrogen and inorganic salt, and isolating the thus-formed nucleoside oxidase from the cultured cells. Various nucleoside-5'-carboxylic acids can be produced, by incubating the novel nucleoside oxidase with a nucleoside having a 5'-hydroxymethyl group, in an aqueous medium under aerobic conditions, and isolating the thus-formed nucleoside-5'-carboxylic acid from the incubation medium. Assay methods for nucleosides in liquid samples are provided, which comprise incubating the sample with nucleoside oxidase, thereby consuming oxygen and generating hydrogen peroxide and nucleoside-5'-carboxylic acid by acting on nucleoside, and quantitatively determining consumed oxygen or liberated hydrogen peroxide. A kit for nucleoside assay is provided, which contains the recited ingredients. |
