Abstract
The conversion of several unusual purine bases into their corresponding ribonucleosides by an inosine-producing mutant of Bacillus subtilis was studied. 2-Chlorohypoxanthine was well ribosidated to 2-chloroinosine as easily as that of hypoxanthine to inosine. Several other unusual purine bases, such as 2-methylhypoxanthine, N2N2-dimethylguanine, 6-methoxypurine, 6-methylthiopurine, and N6-acetyladenine, were also converted into their corresponding ribonucleosides to the same extent as 2-chlorohypoxanthine. On the other hand, 2, 6-dichloropurine, isoguanine, 8-azaguanine, 8-azahypoxanthine, 6-chloropurine, and 6-mercaptopurine were scarcely ribosidated. On inosine de novo formation, the unusual bases which are well ribosidated were generally not inhibitory or only slightly inhibitory, while the bases that are scarcely ribosidated were found to be strongly, moderately, and slightly inhibitory or slightly stimulative.
