Two tyrosine residues, Tyr-108 and Tyr-503, are responsible for the deprotonation of phenolic substrates in vanillyl-alcohol oxidase.

ABSTRACT: A number of oxidoreductases from the VAO/para-cresol methylhydroxylase flavoprotein family catalyze the oxidation of para-substituted phenols. One of the best-studied is vanillyl-alcohol oxidase (VAO) from the fungus Penicillium simplicissimum For oxidation of phenols by VAO to occur, they must first be bound in the active site of the enzyme in their phenolate anion form. The crystal structure of VAO reveals that two tyrosine residues, Tyr-108 and Tyr-503, are positioned to facilitate this deprotonation. To investigate their role in catalysis, we created three VAO variants, Y108F, Y503F, and Y108F/Y503F, and studied their biochemical properties. Steady-state kinetics indicated that the presence of at least one of the tyrosine residues is essential for efficient catalys

SUBMITTER: Ewing TA 

PROVIDER: S-EPMC5582857 | biostudies-literature | 2017 Sep

REPOSITORIES: biostudies-literature