In situ assay of intracellular enzymes of yeast (Kluyveromyces fragilis) by digitonin permeabilization of cell membrane.

The yeast, Kluyveromyces fragilis was permeabilized to a number of low-molecular-weight substrates using digitonin. The activities of intracellular yeast enzymes, viz., alcohol dehydrogenase (ADH), beta-galactosidase, glucose-6-phosphate dehydrogenase, aspartase, and hexokinase were found to be much higher in the permeabilized cells than the untreated cells. The optimum conditions for permeabilization with reference to ADH were 0.1% digitonin at 37 degrees C for 15 min. The ADH activity in permeabilized cells was several-fold higher than that in cell free extracts prepared by either physical or chemical methods.