Heterogeneity of 11 beta-hydroxysteroid dehydrogenase type 1/microsomal carbonyl reductase (11 beta-HSD/CR) in guinea pig tissues. Purification of the liver form suggests modification in the cosubstrate binding site

11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) and xenobiotic carbonyl reductase activities were determined in guinea pig tissue microsomes. The d ata indicate the presence of a NADP(H) dependent form, distinct from the kn own type I isozyme. Purification of 11 beta-HSD-1 from liver microsomes res ulted in two distinct peaks, resolved by dye-ligand chromatography, indicat ing differences in the cosubstrate binding site. Immunoblot analysis using anti 11 beta-HSD-1 antibodies reveals the presence of similar structural de terminants between the enzyme forms. Both have an apparent molecular mass o f 32 kDa, suggesting protein modifications occurring in the type 1 isozyme which account for the differences in chromatographic behaviour. (C) 2000 El sevier Science Ireland Ltd. All rights reserved.