In order to investigate the effect of the different stereochemistry of C-24 on the microbial C-26 oxidation of sterol side-chain the genetically modified Mycobacterium sp. BCS 396 strain was used to transform ergosterol. Ergosterol was converted to 3-oxo-4,22-ergostadien-26-oic acid methyl ester, 3-oxo-1,4,22-ergostatrien-26-oic acid methyl ester, and 3-oxo-1,4,22-ergostatrien-26-oic acid, the structures of which have been determined by IR, 1H NMR, 13C NMR, and mass spectroscopy. The X-ray structure of 3-oxo-4,22-ergostadien-26-oic acid methyl ester revealed that oxidation at C-26 of the ergostane side-chain generates a chiral center with S-configuration at C-25 as a result of chiral induction of the C-24 center. © 1995.
Ambrus, G., Jekkel, A., Ilkoy, É., Horváth, G., & Böcskei, Z. (1995). Novel 26-oxygenated products in microbial degradation of ergosterol. Steroids, 60(9), 626–629. https://doi.org/10.1016/0039-128X(95)00078-5