Full text loading...
Abstract
A strain of Saccharomyces cerevisiae, grown in a medium containing a suboptimal concentration (0·4 × 10−10m) of biotin, was shown to contain less deoxyribonucleic acid (DNA), ribonucleic acid (RNA) and protein but, during the early stages of growth, increased concentrations of acid-soluble ultraviolet (u.v.)-absorbing substances, as compared with the same organism grown in the presence of an optimal concentration (8·0 × 10−10 m) of biotin. The concentration of acid-soluble u.v.-absorbing substances in the biotin-deficient yeast was higher, irrespective of the nature of the extracting acid (0·2v-perchloric acid, 5% (w/v) and 10% (w/v) trichloroacetic acid, or 5 % (v/v) n-butanol in m/15 KH2PO4). Raising the temperature of extraction from 3° to 21° or 30° had little or no effect on the amounts of these u.v.-absorbing substances extracted. Analyses of the nucleotides and nucleo- bases in the yeast RNA showed these to have a ratio of purine:pyrimidine bases of 1·00–1·15, with the exception of the RNA from 5-day cultures of biotin-deficient yeast which had a slightly but consistently higher ratio. The significance of these results is discussed in relation to the metabolic function of biotin.
- Received:
- Published Online: