Characterization of a protein-generated O₂ binding pocket in PqqC, a cofactorless oxidase catalyzing the final step in PQQ production.

ABSTRACT: PQQ is an exogenous, tricyclic, quino-cofactor for a number of bacterial dehydrogenases. The final step of PQQ formation is catalyzed by PqqC, a cofactorless oxidase. This study focuses on the activation of molecular oxygen in an enzyme active site without metal or cofactor and has identified a specific oxygen binding and activating pocket in PqqC. The active site variants H154N, Y175F,S, and R179S were studied with the goal of defining the site of O(2) binding and activation. Using apo-glucose dehydrogenase to assay for PQQ production, none of the mutants in this "O(2) core" are capable of PQQ/PQQH(2) formation. Spectrophotometric assays give insight into the incomplete reactions being catalyzed by these mutants. Active site variants Y175F, H154N, and R179S form a quinoid intermediate (Fi

SUBMITTER: RoseFigura JM 

PROVIDER: S-EPMC4002361 | biostudies-literature | 2011 Mar

REPOSITORIES: biostudies-literature