title: Activity and stability of an entrapped-cell system for the Delta(1)-dehydrogenation of steroids in organic media.
abstract: Whole Arthrobacter simplex cells entrapped in kappa-carra-geenan or in two types of polyurethane foam, or adsorbed on silanized Celite, were tested for the Delta(1)-dehydrogenation of hydrocortisone and its derivatives in organic media. Catalytic activity and stability levels were evaluated for the immobilized cells in buffer with 2.5% (vol/vol) methanol, and in three buffer-saturated solvents (n-octan-1-ol, n-decan-1-ol, and chloroform). The addition of glutamate to the immobilization support stabilized the activity of the immobilized cells in the tested organic media. The system with polyurethane (HYPOL6100)-entrapped cells (with coimmobilized glutamate) in n-decan-1-ol provided the highest long-term activity levels. Several factors involved in the polyurethane-entrapment procedure were also studied.
authors.affiliation: Laboratório de Engenharia Bioquímica, Instituto Superior Técnico, Lisbon, Portugal.
authors.forename: H M
authors.initials: HM
authors.lastname: Pinheiro
authors.forename: J M
authors.initials: JM
authors.lastname: Cabral