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Characterization of cholesterol oxidase from a marine Streptomyces sp. and its cytotoxicity

Alapati, K and Handanahal, SS (2020) Characterization of cholesterol oxidase from a marine Streptomyces sp. and its cytotoxicity. In: Process Biochemistry, 89 . pp. 175-185.

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Official URL: https://doi.org/10.1016/j.procbio.2019.10.024


A marine actinobacterial strain (designated as AKHSS) capable of producing cholesterol oxidase on the enzyme indicator plates was identified as Streptomyces sp. The cell-free lysate of the strain was used for monitoring the production of cholesterol oxidase and the maximal enzyme yields were recorded at 72 h post inoculation. The cholesterol oxidase was purified using polyethylene glycol 4000 precipitation, diethylaminoethyl Sephacel anionic column chromatography and Superdex-200 gel filtration to near homogeneity. Through electron-spray ionization mass spectrometry, molecular mass of the purified enzyme was recorded as 42.84 kDa. The optimum pH of the enzyme was found to be 9 and it was stable up to 60 °C. Metal salts like MgSO4 and ZnSO4 stimulated the enzyme activity. The Vmax and Km of the purified enzyme with cholesterol as substrate were found to be 1.22 μmoles/min/mL and 0.54 mM respectively. The enzyme showed significant cytotoxicity on breast (MCF-7), nasopharyngeal (KB) and ovarian (OVCAR) cancer cell lines at very low concentrations ranging from 0.093 to 0.14 μM, as evident from MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] cell viability assay. Besides, the enzyme exhibited relatively less cytotoxicity on primary mouse embryonic fibroblast (3T3) cells. Thus, cholesterol oxidase of Streptomyces sp. AKHSS could be a potential anticancer agent

Item Type: Journal Article
Publication: Process Biochemistry
Publisher: Elsevier Ltd
Additional Information: The copyright for this article belongs to the Elsevier Ltd.
Keywords: Bacteria; Cell culture; Cells; Cholesterol; Column chromatography; Cytotoxicity; Enzymes; Magnesium compounds; Mass spectrometry; Purification; Zinc compounds, Actinobacteria; Cell viability assays; Cholesterol oxidase; Marine streptomyces; Mouse embryonic fibroblasts; Polyethylene glycol 4000; Potential anticancer agents; Streptomyces, Enzyme activity
Department/Centre: Division of Biological Sciences > Biochemistry
Date Deposited: 02 Feb 2023 09:24
Last Modified: 02 Feb 2023 09:24
URI: https://eprints.iisc.ac.in/id/eprint/79749

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