Conformational flexibility related to enzyme activity: evidence for a dynamic active-site gatekeeper function of Tyr(215) in Aerococcus viridans lactate oxidase.

ABSTRACT: L-Lactate oxidase (LOX) belongs to a large family of flavoenzymes that catalyze oxidation of α-hydroxy acids. How in these enzymes the protein structure controls reactivity presents an important but elusive problem. LOX contains a prominent tyrosine in the substrate binding pocket (Tyr(215) in Aerococcus viridans LOX) that is partially responsible for securing a flexible loop which sequesters the active site. To characterize the role of Tyr(215), effects of substitutions of the tyrosine (Y215F, Y215H) were analyzed kinetically, crystallographically and by molecular dynamics simulations. Enzyme variants showed slowed flavin reduction and oxidation by up to 33-fold. Pyruvate release was also decelerated and in Y215F, it was the slowest step overall. A 2.6-Å crystal structure of Y215F in comp

SUBMITTER: Stoisser T 

PROVIDER: S-EPMC4908395 | biostudies-literature | 2016 Jun

REPOSITORIES: biostudies-literature