An Alternative Proposal for the Reaction Mechanism of Light-Dependent Protochlorophyllide Oxidoreductase.

ABSTRACT: Light-dependent protochlorophyllide oxidoreductase is one of the few known enzymes that require a quantum of light to start their catalytic cycle. Upon excitation, it uses NADPH to reduce the C₁₇-C₁₈ in its substrate (protochlorophyllide) through a complex mechanism that has heretofore eluded precise determination. Isotopic labeling experiments have shown that the hydride-transfer step is very fast, with a small barrier close to 9 kcal mol^-1, and is followed by a proton-transfer step, which has been postulated to be the protonation of the product by the strictly conserved Tyr189 residue. Since the structure of the enzyme-substrate complex has not yet been experimentally determined, we first used modeling techniques to discover the actual substrate binding m

SUBMITTER: Silva PJ 

PROVIDER: S-EPMC9778109 | biostudies-literature | 2022 Feb

REPOSITORIES: biostudies-literature