ABSTRACT
This chapter discusses the relationship between structure and function in hydroxysteroid dehydrogenases (HSD). It is only in the last decade that the role of HSD in regulating the actions of steroids has been appreciated. This mechanism for regulating steroid hormone action was uncovered in several laboratories studying various aspects of high blood pressure. The Homology program was used to model a 255-residue segment of 11β-HSD and a helix F of 17β-HSD on the S. hydrogenans 20β-HSD template. Several lines of evidence—sequence analysis, mutagenesis studies, and the solved 3D structure of homologs of 11β-HSD—indicate that the nucleotide binding site in these enzymes has many similarities to that in other classes of dehydrogenases. Knowledge of structure-activity relationships for the binding site on steroid dehydrogenases will be helpful in identifying novel compounds from plants and other sources that could be useful in regulating steroid dehydrogenases.
