Short‐chain dehydrogenases/reductases (SDRs) are enzymes of great functional diversity.
Even at sequence identities of typically only 15–30%, specific sequence motifs are
detectable, reflecting common folding patterns. We have developed a functional assignment
scheme based on these motifs and we find five families. Two of these families were known
previously and are called 'classical'and 'extended'families, but they are now distinguished at
a further level based on coenzyme specificities. This analysis gives seven subfamilies of …