Effect of 4-6 Dinitro-O-Cresol on Oxidation of d'- and l'-Arabinose by Previously Starved Yeast.

Abstract

It has been shown in previous papers from, this laboratory that the respiratory rate of yeast suspended in non-nutrient phosphate buffer solutions or in glucose phosphate can be markedly increased on treatment with proper concentrations of 2–4 dinitrophenol (DNP), 4–6 dinitro-o-cresol (DOC) and some related compounds.1–5 We report herewith the results of experiments in which it is shown that the effects of such metabolic stimulants upon the respiration of yeast is profoundly affected by the type of “exogenous”6 carbohydrate fuel available.A pure culture of Saccharomyces cerevisiae and pure culture methods were used throughout. The experimental procedures were the same as described previously2,3 except that yeast was first grown 48 hours on Orla-Jensen agar medium, then taken up in 0.2M phosphate buffer, pH 6.8, and starved 24 hours under aerobic conditions in Fraser tubes7 at 25° ± 0.02°C. before the beginning of each experiment. Respiration was measured in the conventional form of Warburg apparatus at 25...