Nature of transformation of hydrocortisone by cells incorporated into polyacrylamide gel.

The ability of Mycobacterium globiforme 193 cells immobilized in polyacrylamide gel (Paag) to transform soluble and microcrystalline hydrocortisone was investigated under conditions to periodic aeration. It was found that the specific 3-oxosteroid-delta'-dehydrogenase activity of immobilized cells hardly differs from that of free cells and averages 0.06 mumole/mg cells . min; the quantitative and qualitative composition of the transformation products formed by free and immobilized cells was identical. The linear relation between the accumulation of the reaction product, prednisolone, and the transformation time, the absence of an activating effect of SAA [surface-active agents] on the 3-oxosteroid-delta'-dehydrogenase activity, the correlation between enzymatic activity and viability, and the absence of an increase in activity during repeated transformations indicate that the cytoplasmic membrane of Myc. globiforme is not a significant diffusion barrier for the reaction substrate and product. Maintenance of immobilized cells in a viable state is a necessary condition of the retention of enzymatic activity by these cells. "Activation" of immobilized cells is achieved by incubating the granules in nutrient medium. The cause of the "activation," in our opinion, is the appearance of a new surface and, probably, internal cell population.