Abstract
Two genes (choRI and choRII) encoding cholesterol oxidases belonging to the vanillyl-alcohol oxidase (VAO) family were cloned on the basis of putative cholesterol oxidase gene sequences in the genome sequence data of Rhodococcus erythropolis PR4. The genes corresponding to the mature enzymes were cloned in a pET vector and expressed in Escherichia coli. The two cholesterol oxidases produced from the recombinant E. coli were purified to examine their properties. The amino acid sequence of ChoRI showed significant similarity (57%) to that of ChoRII. ChoRII was more stable than ChoRI in terms of pH and thermal stability. The substrate specificities of these enzymes differed distinctively from one another. Interestingly, the activities of ChoRII toward β-cholestanol, β-sitosterol, and stigmasterol were 2.4-, 2.1-, and 1.7-fold higher, respectively, than those of cholesterol. No cholesterol oxidases with high activity toward these sterols have been reported so far. The cholesterol oxidation products from these two enzymes also differed. ChoRI and ChoRII oxidized cholesterol to form cholest-4-en-3-one and 6β-hydroperoxycholest-4-en-3-one, respectively.
Highlights
An essential component of mammalian cells, cholesterol is involved in cell function and viability
On the basis of the putative cholesterol oxidase gene sequence in the genome sequence data of strain PR4, we identified two cholesterol oxidases belonging to the vanillyl-alcohol oxidase (VAO) family
We found two genes encoding cholesterol oxidases belonging to the vanillyl-alcohol oxidase (VAO) family in the genome sequence of R. erythropolis PR4
Summary
An essential component of mammalian cells, cholesterol is involved in cell function and viability. It is a principal component of the plasma membrane and is a precursor to steroid hormones, bile acids, and vitamin D. High serum cholesterol levels are associated with increased risk for cardiovascular disease and many cancers [1]. Cholesterol oxidases (EC 1.1.3.6) have been widely used for the clinical determination of serum cholesterol level [2]. Cholesterol oxidases have varieties of applications, including the production of valuable steroidal compounds [5, 6] and nonsteroidal chiral compounds [7] as well as insecticidal activity [8, 9]. DS-1 has been shown to reduce oxysterol cytotoxicity in human fibroblasts [10]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
