The influence of polymerization conditions on the 3-ketosteroid delta 1-dehydrogenase activity of Mycobacterium globiforme cells included in a gel.

The influence of the conditions of polymerization and the structure of the polyacrylamide gel (PAG) on the 3-ketosteroid delta 1-dehydrogenase activity of a culture of M. globiforme 193 was studied. A clear dependence of the enzymatic activity on the temperature regime and the duration of the polymerization process was established. The reason for the fall in activity with a rise in temperature and an increase in the duration of the polymerization process is the diminution of the quantity of viable cells. The death of the cells is caused by the action of the monomers. The maximum 3-ketosteroid delta 1-dehydrogenase activity appears when the immobilized cells are maintained in a viable state, accomplished by adopting a short time of polymerization (1--2 min) at a temperature of 4--12 degrees C. The specific activity of free cells of M. globiforme and cells immobilized under these conditions is 0.15 mumoles/mg cells . min. The reason for the low activity in a 20% gel is apparently the limited rate of diffusion of the substrate into the gel, conditioned by the small dimensions of the pores of the gel. A change in the concentration of N,N'-methylene bisacrylamide (MBA) from 0.25 to 2% in 5 and 10% gels does no affect the rate of delta 1-dehydrogenation of the substrate.