title: 11 alpha-hydroxylation of progesterone using modified alginate-immobilized cells.
abstract: The major disadvantage of using alginate-immobilized Aspergillus ochraceus for 11 alpha-hydroxylation of progesterone is its instability in phosphate solutions. In this study, different gel-hardening methods were used to improve the stability of alginate gels. Addition of Fe3+ and Fe2+ ions increased the activity of hydroxylation, but Fe2+ was not a good gelling agent. Replacement of CaCl2 by FeCl3 as the gelling agent increased the activity of the immobilized cells by about 33%. Hardening the alginate-immobilized cells with polyacrylamide (PAA) increased their stability in a 0.1 M phosphate buffer from 0.35 h to over 36 h. The productivity was increased by a factor of 1.8 compared to those without hardening, and the maximum yield was also increased from 84.3% to 90.8%. The physical properties and biocatalytic characteristics of PAA-hardened, immobilized cells were found to be feasible for application in a steroid bioconversion system.
authors.affiliation: Department of Chemical Engineering, National Tsing Hua University, Hsinchu, Taiwan, Republic of China.
authors.forename: K C
authors.initials: KC
authors.lastname: Chen
authors.forename: W S
authors.initials: WS
authors.lastname: Yin
authors.forename: C
authors.initials: C
authors.lastname: Tiu
authors.forename: J Y
authors.initials: JY
authors.lastname: Houng
mesh_terms: D000180:Acrylic Resins; D000464:Alginates; D001235:Aspergillus ochraceus / Q000201:enzymology* / Q000502:physiology; D002021:Buffers; D002413:Cations, Divalent / Q000494:pharmacology; D003577:Cytochrome P-450 Enzyme System; D004800:Enzymes, Immobilized; D005656:Fungal Proteins / Q000378:metabolism*; D005782:Gels; D020723:Glucuronic Acid; D006603:Hexuronic Acids; D006863:Hydrogen-Ion Concentration; D006900:Hydroxylation; D007501:Iron / Q000494:pharmacology; D008863:Microspheres; D011374:Progesterone / Q000378:metabolism*; D013172:Spores, Fungal; D013250:Steroid Hydroxylases / Q000378:metabolism*; D013696:Temperature; D000099166:Polyacrylamides
chemical_list: D000180:Acrylic Resins; D000464:Alginates; D002021:Buffers; D002413:Cations, Divalent; D003577:Cytochrome P-450 Enzyme System; D004800:Enzymes, Immobilized; D005656:Fungal Proteins; D005782:Gels; D020723:Glucuronic Acid; D006603:Hexuronic Acids; D007501:Iron; D011374:Progesterone; D013250:Steroid Hydroxylases; D000099166:Polyacrylamides; C074514:steroid 11-alpha-hydroxylase