SDR: Structure, mechanism of action, and substrate recognition

Short-chain dehydrogenases/reductases (SDR) constitute a large protein fami ly. The SDR family now includes more than 1,000 enzymes from humans, mammal s, insects and bacteria, and exhibits a wide variety of substrate specifici ty for steroids, retinoids, prostaglandins, sugars, alcohols and other smal l molecules. These enzymes have a residue identity level of 15-30 %. Much h as been done in the last decade to understand the structure-function relati onships in the SDR enzymes. This review summarizes recent progress of struc tural and functional studies of the enzymes belonging to the SDR family (X- ray crystal structure analyses and site-directed mutagenesis studies). Base d on these studies, the three-dimensional structure, catalytic mechanism, c oenzyme specificity, and substrate specificity of the SDR enzymes are discu ssed.