Abstract
Menadione promoted the production of active oxygen species (AOS) in both yeast cell suspension and the crude enzymes from the cells, but menadione sodium bisulfite (MSB) had little effect on the production of AOS in the cell suspension. MSB kept the stable increase in the electron transfer from intact yeast cells to anode compared to menadione, but the electron transfer promoted by MSB was inhibited in permeabilized yeast cell suspension. Menadione promoted oxidation of NAD(P)H much faster than MSB in permeabilized yeast cell suspension, suggesting the oxidative stress due to consumption of NAD(P)H. The proliferation of yeast cells was inhibited by menadione under aerobic conditions rather than anaerobic conditions, and the inhibitory effect was reduced by superoxide dismutase and catalase. The effect of MSB on the proliferation was much smaller than that of menadione. The above facts suggest that harmless MSB promotes the electron transfer from plasma membrane of yeast cells to anode. On the other hand, harmful menadione might promote the electron transfer from cytosol and plasma membrane to anode and dissolved oxygen.