ABSTRACT
Alcohol dehydrogenases (ADHs) are oxidoreductases that break down alcohol. They catalyze the oxidation of a variety of substrates, which is followed by the reduction of appropriate electron acceptors, most commonly NAD+/NADP+, FAD or FMN. Alternatively, one or more hydride ions are transferred from substrates to oxidizing cofactors/electron acceptors. They are predominantly metalloproteins, which are conjugated proteins with zinc as a prosthetic group engaged in the conversion of aliphatic and aromatic alcohols to their respective aldehydes (reversibly or irreversibly). It plays a critical part in the electron transfer chain or the respiratory chain pathway. ADHs are commonly utilized as biocatalysts for the dynamic and kinetic resolution of racemic substrates, as well as the manufacture of enantiomerically pure compounds. These enzymes also help to protect us from free radicals that can react with the biomolecules in our cells. They serve a key function in the prevention of acidosis and the formation of lignin in plants. Human ADH is a classic example of an MDR superfamily Zn-containing dimer. ADH is further categorized into seven categories, ADH1–7, based on the amount of sequence similarity and enzymatic characteristics. The embryonic expression and substrate specificity of each of the seven ADH are distinct. Zinc, serine (OH-Ser 48), histidine (His 51, 67), isoleucine (C=O-Ile 269) and cysteine make up the active site of ADH (Cys 46 and 174). This chapter highlights the differential role of ADH as well as mode of action. It includes several physiological functions such as skin and other epithelial cell growth, drug metabolism, reactive chemical defense, stress survival and so on. The importance of ADH in industries, healthcare, diagnostics, environmental monitoring and genetic engineering has been summarized with the goal of better understanding ADH's future possibilities in biotechnology.
