Penning T, Burczynski M, Jez J, Hung C, Lin H, Ma H, et al. Human 3alpha-hydroxysteroid dehydrogenase isoforms (AKR1C1-AKR1C4) of the aldo-keto reductase superfamily: functional plasticity and tissue distribution reveals roles in the inactivation and formation of male and female sex hormones. Biochem J. 2000;351:67-77 pubmed
..These studies are in stark contrast with those in rat where only a single AKR with positional- and stereo-specificity for 3alpha-hydroxysteroids exists. ..
Penning T, Burczynski M, Jez J, Lin H, Ma H, Moore M, et al. Structure-function aspects and inhibitor design of type 5 17beta-hydroxysteroid dehydrogenase (AKR1C3). Mol Cell Endocrinol. 2001;171:137-49 pubmed
..With regards to transition state analogs steroid carboxylates and pyrazoles may be preferred while 3alpha, 17beta or 20alpha-spiro-oxiranes may act as mechanism-based inactivators. ..