RESUMO
The role of a variety of compounds including organic acids, vitamins, growth promoting substances, purines and pyrimidines in the bioconversion of cortisol with Bacillus cereus was investigated. The transformation of cortisol to prednisolone and pregn-4-en-11beta, 17alpha,20beta, 21-tetrol-3-one was affected by these compounds in different manners. The enzymatic delta1-dehydrogenation reaction was greatly induced with fumarate, menadione, and xanthine treatments. However, the enzymic reduction of the 20-carbonyl to the 20beta-ol was specifically stimulated with fumarate, nicotinic acid amide, and uracil treatments.
Assuntos
Bacillus cereus/enzimologia , Hidrocortisona/metabolismo , Ácidos/farmacologia , Biotransformação , Ácidos Indolacéticos/farmacologia , Prednisolona/biossíntese , Pregnenos/biossíntese , Uracila/farmacologia , Vitaminas/farmacologia , Xantinas/farmacologiaRESUMO
The formation of progesterone hydroxylases by Aspergillus niger 173 was investigated. The constitution of the fermentation medium influenced both the yield and the type of enzymes catalyzing the transformation of progesterone. The enzyme yield also varied with the pH value at which induction was performed as well as with the buffer used. The transformation activity of progesterone was more pronounced with mycelia induced in citrate-phosphate than in phosphate buffer. The results demonstrated that induction of 6beta-hydroxylase was favoured at pH values near neutrality while that of 11alpha-hydroxylase in the presence of citrate ions. The transformation activity of progesterone was optimal at pH 5.0. The action of 11alpha-hydroxylase was also optimal at pH 5.0, but other hydroxylase showed pH optima between 2.2 and 4.0. Progesterone concentrations higher than 6 mg in 50 ml reaction mixture was a limiting factor for the rate of transformation activity.