Tong-Yi Dou1, Hong-Wei Luan, Xing-Bao Liu, Shi-Yang Li, Xun-Fu Du, Ling Yang. 1. Laboratory of Pharmaceutical Resource Discovery, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457, Zhongshan Road, Dalian, 116023, Liaoning, People's Republic of China.
Abstract
OBJECTIVES: To find extracellular biocatalysts that can specifically and efficiently remove the C-7 xylosyl group from 7-xylosyltaxanes. RESULTS: A Cellulosimicrobium cellulans strain F16 that can remove the C-7 xylosyl group from 7-xylosyltaxanes was isolated from the root soil of an old Taxus yunnanensis tree. Using corn cob as sole carbon source, the maximum 7-xylosyl-10-deacetylpaclitaxel β-xylosidase activity of 9.6 U l(-1) was achieved. The β-xylosidase could be trapped by a ceramic tubular membrane (pore size 50 nm), and exhibited an apparent molecular weight much greater than 500 kDa. Under optimized conditions, 3.75 l cell-free culture medium transformed 2 grams 7-xylosyltaxane mixtures to their corresponding aglycones within 3 h, with a conversion >98%. CONCLUSION: This is the first report that C. cellulans can produce extracellular β-xylosidases capable of removing the C-7 xylosyl group from 7-xylosyltaxanes.
OBJECTIVES: To find extracellular biocatalysts that can specifically and efficiently remove the C-7 xylosyl group from 7-xylosyltaxanes. RESULTS: A Cellulosimicrobium cellulans strain F16 that can remove the C-7 xylosyl group from 7-xylosyltaxanes was isolated from the root soil of an old Taxus yunnanensis tree. Using corn cob as sole carbon source, the maximum 7-xylosyl-10-deacetylpaclitaxel β-xylosidase activity of 9.6 U l(-1) was achieved. The β-xylosidase could be trapped by a ceramic tubular membrane (pore size 50 nm), and exhibited an apparent molecular weight much greater than 500 kDa. Under optimized conditions, 3.75 l cell-free culture medium transformed 2 grams 7-xylosyltaxane mixtures to their corresponding aglycones within 3 h, with a conversion >98%. CONCLUSION: This is the first report that C. cellulans can produce extracellular β-xylosidases capable of removing the C-7 xylosyl group from 7-xylosyltaxanes.