SUBCELLULAR LOCALIZATION OF ALCOHOL DEHYDROGENASE ACTIVITY IN BAKERS YEAST

The subcellular location of the NAD-dependent alcohol dehydrogenase activity in baker's yeast has been studied. The alcohol dehydrogenase activities in the particulate fraction sedimenting between 3000 and 15 000 × g and in the 100 000 × g supernatant obtained from protoplasts were examined spectrophotometrically and by electrophoresis on polyacrylamide gels. During the exponential and stationary phases of growth, glucose-grown cultures contain alcohol dehydrogenase activity with low reactivity to cinnamyl alcohol in both the particulate fraction and the 100 000 × g supernatant. In each case the particulate fraction contains one band on electrophoresis, whereas two bands are observed in the 100 000 × g supernatant of the stationary phase cultures. The second band, which is not present in freshly prepared 100 000 × g fractions of exponential phase cultures, appears upon storage of the preparations at 4°. In ethanol-grown cultures, the electrophoretic patterns in both the particulate and 100 000 × g supernatant fractions are similar to those seen in glucose-grown cultures, but the activity with cinnamyl alcohol as substrate relative to the activity with ethanol is high in the 100 000 × g supernatant as compared with the other fractions. It appears that baker's yeast can produce at least three NAD-dependent alcohol dehydrogenases, one of which is associated with a particulate fraction and two with the soluble portion of the cytoplasm. © 1969.