The Model of the Δ1-dehydrogenation of 3-ketosteroid Substrates by Arthrobacter globiformis ATCC 31250

摘要

The conversion rule of the 3-ketosteroid-Δ1-dehydrogenation by Arthrobacter globiformis ATCC 31250 and the effect of the cell wall and cell membrane on biotransformation have been studied. Steroid compounds with different functional groups show a diversity of physicochemical properties at the macroscopic level. We measured the melting point, specific rotation and absorption coefficient of 3-ketosteroid substrates as independent variables, and the biotransformation rate of Δ1-dehydrogenation as target variable. A mathematical model describing the bioconversion rule during the process of 3-ketosteroid-Δ1-dehydrogenation with whole cells was established using MatLab software. The solution of the derived model agrees well with experimental data. The broken cell extract were prepared by Ultrasonic, in order to make the substrates direct contact with Δ1-dehydrogenase. Experimental results showed the sequence of substrates in the whole-cell biotransformation, sorted from the highest to the lowest in the order of bioconversion rate, are Cortisone, Cortisone Acetate, 4-AD, Methyltestosterone, RSA, with debrominative substance not transformed. And the bioconversion rate of broken cells were lower than that of intact cells. Mathematical model showed that melting point and absorption coefficient increase the rate of biotransformation, while specific rotation decreases the rate of bioconversion. Cells' integrality has taken key roles in the process of bioconversion.