Background: Alcohol dehydrogenases (ADHs) which are belong to Oxidoreductase family, can convert alcohol to aldehyde. Several subunits exist in ADH is divided into two main groups including catalytic domain and coenzyme binding domain. The catalytic domain would be linked to zinc atom and the second zinc has a role in protein structure. This study aimed to examine the effect of zinc on the benzyl alcohol dehydrogenase (BADH) in Rhodococcus sp.

Materials and Methods: The recombinant BADH was purified by NI-NTA column using AKTA prime. The biochemical characteristics of the protein were determined based on NAD-NADH reaction at 340 nm. The amino acid alignments and protein structure of BADH were evaluated.

Results: The BADH has this potential to use many aromatic hydrocarbons such as toluene and benzyl alcohol as a substrate and convert them to benzaldehyde which was detected by Gas Chromatography- Mass Spectrophotometry. The optimal activity of enzyme was obtained at Zinc concentration of 1.2 mM. The lack of Zinc (Zn²⁺) led to no BADH activity. At optimal temperature of 25°C and pH lower than 6.0, both activity and the amount of Zinc in BADH were decreased. Based on amino acid alignment, a metallo-structure was shown in the BADH and there were two zinc ion binds in each molecule as a cofactor.

Conclusion: The BADH from Rhodococcus sp is a zinc-dependent alcohol dehydrogenase, which is related to a diverse group of proteins such as mammalian ADH (class I), zinc-dependent alcohol dehydrogenase and formaldehyde dehydrogenase.