The Bombay Technologist

Design of Enzymatic Systems for Redox Reactions

Tanmay P. Gharat

Chemical Engineering Department

Keywords: Oxidases, Tyrosinase, Glucose Oxidase, p-Cresol, Glucose, Gluconic Acid, Catechol, p-Benzoquinone, Immobilization.

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Abstract

Oxidases are enzymes capable of carrying out redox reactions involving molecular oxygen and have huge industrial potential. Their applications usually involve additional agents that can prevent deactivation of enzyme and recover the final product. Tyrosinase and Glucose oxidase (GOX) are two such oxidases, capable of using molecular oxygen and oxidising monophenols such as p-cresol, and glucose, respectively to 4-methyl-quinone and gluconic acid. The o-quinone, so formed can function as electron acceptor for GOX, thereby reducing poisoning of the enzyme and also converting it to catechol derivative. The present work, therefore, attempts to integrate the two enzymes and their reactions resulting in 4-methyl catechol and gluconic acid as end-products. The methodology involves study of immobilized GOX for conversion of glucose in oxygen saturated and oxygen-depleted p-benzoquinone solutions, followed by studies with 4-methyl orthobenzoquinone and finally integration into the tyrosinase reaction system. Immobilized on suitable resin, GOX shows 80% conversion of glucose in oxygen-depleted benzoquinone solutions with gluconic acid and hydroquinone as products, both in batch and column modes. Studies are being carried out to extend the system to other catechol.