Structure and Function of the enzymes belonging to the SDR (Short-chain Dehydrogenase/Reductase) Family

A group of short-chain dehydrogenases/reductases (SDR) has recently been identified. These enzymes utilize NAD (H) or NADP (H) as cofactors and exhibit a wide variety of substrate specificities. Crystal structure analyses have been completed for some of these enzymes, but none of them have targeted the ternary (enzyme-coenzyme-substrate analogue) complexes.We have recently solved the crystal structures of the ternary complex (with NAD (H) ) of 7α-hydroxysteroid dehydrogenase from E. coli and that (with NADP (H) ) of mouse lung carbonyl reductase. These two structures enabled us to discuss the catalytic mechanism and the origin of coenzyme specificities (NAD (H) or NADP (H) ) common to the enzymes of the SDR family.