Enzymatic transformation of 3-ketosteroid

Abstract

This research is concerned with production of medically important steroid compound that is one of the anti-inflammatory agents. It is of some industrial importance to develop a process of enzymatic transformation of steroid. In this research 3-ketosteroiddelta-1-dehydrogenase was first produced by using $\mbox{\underline{Arthrobacter}}$ $\mbox{\underline{sim}}$ $\mbox{\underline{plex}}$ strain. In the production of the enzyme, several important process variables have been optimized in order to maximize the enzyme productivity. These variables include fermentation conditions made of enzyme induction, and preparation of whole-cell-enzyme. The whole-cell-enzyme was prepared by washing the cells with buffer and acetone followed by heat treatment under mild conditions. The whole-cell-enzyme so obtained retained high enzymatic activity and could be used in both batch and continuous reaction system. The whole-cell-enzyme offers significant advantages over the other forms of enzyme preparation. For instance, continuous operation, reusability, easy storage, free from contamination, etc. With such advantages, the use of whole-cell-enzyme proves to be more economical than the purified enzyme, purified-immobilized enzyme, and the growing cells in fermentation system. In order to develop the steroid process by the enzymatic transformation, it was important to determine kinetic constants of the whole-cell-enzyme produced. Km constant and Vm(Maximum velocity)determined were $1.57\times10^{-13}M$ and $2.07\times10^{-4}M/\min$ respectively. These values of the kinetic constants determined were found to be significantly different from those constants obtained for the partially purified enzyme. This difference was believed to be due to the mass transfer limitation through the cell membrane barrier and steroid solubility under the conditions of experiments used. We found that the dehydrogenase enzyme prepared from $\mbox{\underline{A}}$. $\mbox{\underline{simplex}}$ cells did not ...