Abstract
The inhibitory effect of methylated β-cyclodextrin (mCD) on steroid degradation was studied using the degradation of 9α-hydroxyandrost-4-ene-3,17-dione (9-OH-AD) by Mycobacterium sp. VKM Ac-1817D as a model process. The formation of the [9-OH-AD–mCD] complex was shown by 1H NMR-spectroscopy. The biodegradation of 9-OH-AD by whole and disrupted cells was carried out at 30°C in aqueous solutions with or without mCD. Enzyme kinetic parameters were calculated by non-linear regression of the Michaelis–Menten plot. The complexation of 9-OH-AD and mCD was evaluated via the stability constant for the [9-OH-AD–mCD] complex. The Vmax and KM values calculated for the free (non-complex) steroid in mCD solutions corresponded to steroid degradation in the absence of mCD. The inclusion complex [9-OH-AD–mCD] was shown to be resistant to enzymatic degradation. The inference is made that the ‘‘guest–host’’ molecular complexation with cyclodextrin can be used for the control of steroid bioconversions.