Medium- and short-chain dehydrogenase/reductase gene and protein families : Structure-function relationships in short-chain alcohol dehydrogenases

The structure-function relationships of alcohol dehydrogenases from the large family of short-chain dehydrogenase/reductase (SDR) enzymes are described. It seems that while mammals evolved with a medium-chain alcohol dehydrogenase family (MDR), fruit flies utilized an ancestral SDR enzyme. They have modified its function into an efficient alcohol dehydrogenase to aid them in colonizing the emerging ecological niches that appeared around 65 million years ago. To the scientific community, Drosophila has now served as a model organism for quite some time, and Drosophila alcohol dehydrogenase is one of the best-studied members of the SDR family. The availability of a number of high-resolution structures, accurate and thorough kinetic work, and careful theoretical calculations have enabled an understanding of the structure-function relationships of this metal-free alcohol dehydrogenase. In addition, these studies have given rise to various hypotheses about the mechanism of action of this enzyme and contribute to the detailed knowledge of the large superfamily of SDR enzymes.