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In this study we determined some properties of the cholesterol oxidase from a Brevibacterium strain isolated from buffalos milk and identified the cholesterol degradation products by the bacterial cell. A small fraction of the enzyme synthesized by cells cultured in liquid medium for 7days was released into the medium whereas a larger fraction remained bound to the cell membrane. The extraction of this fraction was efficiently accomplished in 1 mM phosphate buffer, pH 7.0, containing 0.7% Triton X-100. The enzyme stability under freezing and at 45 o C was improved by addition of 20% glycerol. The optimum temperature and pH for the enzyme activity were 53°C and 7.5, respectively. The only steroidal product from cholesterol oxidation by the microbial cell and by the crude extract of the membrane-bound enzyme was 4-colesten-3-one. Chromatographic analysis showed that minor no steroidal compounds as well as 4-colesten-3-one found in the reaction media arose during fermentation process and were extracted together with the enzyme in the buffer solution. Cholesterol oxidation by the membrane-bound enzyme was a first order reaction type.

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Synthesis of 7-Ethoxycarbonyl-7,8-dehydrorutecarpine. -The title compound (VII) is prepared via aza-Wittig reaction of the intermediate (IV). (VII) is a derivative of the alkaloid rutecarpine and may have pharmacologically interesting properties. -(RODRIGUES, J. A. R.; MORETTO, A. L.; J.