Bioinformatics Based Investigation on the Assortment of Industrially Accessible Azodyes with Azoreductase Enzyme of Pseudomonas putida

Azo dyes are the most widely applied chemical dyes that have also raised great concerns for
environmental contamination and human health issues. There has been an increased interest in
discovering new novel bioremediation strategies to degrade azo dyes for environmental issues and
also economic purposes. Azoreductase are key enzymes evolved in nature capable of degrading the
azo dyes. As azoreductase enzyme is a key enzyme in degrading these azo dyes, they are good and
potential candidates for industrial wastewater treatment and environmental restoration. The initial
critical step of reduction of azo bond during the metabolism of azo dyes is catalysed by a group of
NADH and FAD dependant enzyme called azoreductase. Although several azoreductase have been
identified from microorganisms and partially characterized, very little is known about the structural
basis of the substrate specificity and the nature of catalysis. Azoreductase enzyme of Pseudomonas
putida has a wider broad spectrum of substrate specificity and capable of degrading a wide variety of
azo dyes. In the present study, the crystal structure of the enzyme from PDB and 10 azo dyes from
NCBI PubChem compound were retrieved and their interactions were studied. These azo dyes were
then docked with the FMN-dependent NADH-azoreductase enzyme to analyse the binding affinity of
the azo dyes with the enzyme and predict the catalytic sites. Consequently, the catalytic residues of
FMN-dependent and NADH dependent enzyme were then analysed in terms of properties including
function, hydrogen bonding and flexibility. The results suggest that Ala-114, Phe-172 and Glu-174
play a predominant role as catalytic site residues in the enzyme. Furthermore, the approach
emphasis on predicting the active sites of this enzyme where substrates can bind in order to give a
better understanding of the biodegradation of some of the commercially important azodyes mediated
by azoreductase. These results will pave way for further increase in azoreductase activity and for
better understanding of the dye degradation pathway. In addition to it, the different types of azo
reductases can be further biochemically characterized for their novelty in near future.