Mechanistic reappraisal of early stage photochemistry in the light-driven enzyme protochlorophyllide oxidoreductase.

ABSTRACT: The light-driven enzyme protochlorophyllide oxidoreductase (POR) catalyzes the reduction of protochlorophyllide (Pchlide) to chlorophyllide (Chlide). This reaction is a key step in the biosynthesis of chlorophyll. Ultrafast photochemical processes within the Pchlide molecule are required for catalysis and previous studies have suggested that a short-lived excited-state species, known as I675*, is the first catalytic intermediate in the reaction and is essential for capturing excitation energy to drive subsequent hydride and proton transfers. The chemical nature of the I675* excited state species and its role in catalysis are not known. Here, we report time-resolved pump-probe spectroscopy measurements to study the involvement of the I675* intermediate in POR photochemistry. We show that I6

SUBMITTER: Heyes DJ 

PROVIDER: S-EPMC3458894 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature