SciELO - Scientific Electronic Library Online

 
vol.30 issue4Growth and endoglucanase activity of Acetivibrio cellulolyticus grown in three different cellulosic substratesPurification of microbial b-galactosidase from Kluyveromyces fragilis by bioaffinity partitioning author indexsubject indexarticles search
Home Pagealphabetic serial listing  

Services on Demand

Journal

Article

Indicators

Related links

Share


Revista de Microbiologia

Print version ISSN 0001-3714

Abstract

SALVA, Terezinha J.G. et al. Some enzymatic properties of cholesterol oxidase produced by Brevibacterium sp. Rev. Microbiol. [online]. 1999, vol.30, n.4, pp.315-323. ISSN 0001-3714.  http://dx.doi.org/10.1590/S0001-37141999000400005.

In this study we determined some properties of the cholesterol oxidase from a Brevibacterium strain isolated from buffalo's 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 45oC 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.

Keywords : Cholesterol oxidase; Brevibacterium sp; cholesterol; 3b-hydroxysteroid oxidase.

        · abstract in Portuguese     · text in English     · English ( pdf epdf )

 

Creative Commons License All the contents of this journal, except where otherwise noted, is licensed under a Creative Commons Attribution License