Engineering of a skin-fiber-opening enzyme for sulfide-free leather beam house operation through xenobiology†
The leather industry contributes significantly to the Indian economy; however, it is encountering several environmental regulation challenges due to heavy pollution caused through the discharge of enormous amounts of liquid and solid hazardous waste. Environmental regulation is forcing the leather industry to adopt cleaner and greener production practices. There has been considerable research emphasis on alternative enzyme-based pre-tanning processes, but most of the enzymatic processes result in inferior quality due to the lower enzymatic activity under harsh conditions. In this study, for the first time, next-generation rational enzymatic evolution has been attained through a greener approach for leather processing by combining computational and xenobiology approaches. The next-generation rational engineering of α-1,4-glycosidic hydrolase resulted in a novel xenobiocatalyst with an additional hydroxyl group in the protein core used for green leather processing. It remarkably enhanced the catalytic efficiency (up to 120-fold higher than that of the wild-type) and turnover rate with chondroitin sulfate, a predominant glycosaminoglycan present in the extracellular matrix of skin, resulting in expeditious skin fiber opening (10 min) without damaging the network. The evolved biocatalyst significantly reduced the chemical oxygen demand, and the total solid effluent load was found to be 8.5 and 22 kg t−1 as compared to the traditional chemical method (13 and 53 kg t−1). Furthermore, the release of chromium and water usage (three times less) were also minimized compared to in the case of the conventional method.