ORCID
- Shubhrima Ghosh: 0000-0001-5683-1944
Abstract
Cholesterol oxidation leads to the development of several oxysterols such as 7-ketocholesterol (7KC), which are linked to various age-related conditions. An approach to reduce their toxicity is proposed using enzymes from microbial sources to degrade them. Our earlier studies identified Pseudomonas aeruginosa PseA and Rhodococcus erythropolis MTCC 3951 as potential strains capable of using 7KC as their sole carbon source. These strains produced cholesterol oxidase as the primary enzyme in the degradation pathway. To enhance applicability, cholesterol oxidase (ChOx) enzymes from P. aeruginosa PseA (ChOxP), R. erythropolis MTCC 3951 (ChOxR), and a commercial variant from Streptomyces sp. (ChOxS) were immobilized on silane functionalized silica nanoparticles (SNP) using covalent-coupling methods. The immobilization efficiency was 68 %, 86 %, and 83 % for ChOxP, ChOxR, and ChOxS respectively. The catalytic efficiency of the immobilized enzyme was nearly twice that of the free enzyme, with increased stability across a wide range of temperatures (10–70°C) and pH levels (4.0–9.0), although the optimum pH (7.5) and temperature (30°C) remained unchanged. The nano-immobilized cholesterol oxidases were reusable up to 10 cycles. Further, enzyme immobilization on nanoparticles was confirmed by FTIR, SEM, and TEM. Biotransformation of cholesterol and 7KC using the nanobioconjugates produced pharmaceutically important molecules 4-cholesten-3-one and 4-cholesten-3,7-dione respectively.
Keywords
7-Ketocholesterol, Biotransformation, Cholestenone, Cholesterol Oxidase, Immobilization, Nanoparticles
DOI Link
Publication Date
2025-01-01
Publication Title
Journal of Steroid Biochemistry and Molecular Biology
Volume
252
ISSN
0960-0760
Deposit Date
2026-11-05
Funding
Shubhrima Ghosh expresses sincere gratitude to the Indian Institute of Technology Delhi for the Senior Research Fellowship provided during her PhD tenure which encompasses this work. Razi Ahmad extends heartfelt thanks to DST-SERB (PDF/2016/000090) for granting the National Postdoctoral Fellowship. The valuable support provided by the Central Instrument Lab (Department of Chemistry) for FTIR and HPLC facilities, SEM facility (Department of Textile Engineering), and TEM facility (CRF) at IIT Delhi is also deeply appreciated.
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License
Additional Links
Recommended Citation
Ghosh, S., Ahmad, R., Gautam, V., & Khare, S. (2025) 'Immobilization of cholesterol oxidases on functionalized Silica Nanoparticles for biotransformation of cholesterol and 7-ketocholesterol', Journal of Steroid Biochemistry and Molecular Biology, 252. Available at: 10.1016/j.jsbmb.2025.106774