Dynamic Determination of Active-Site Reactivity in Semiquinone Photolyase by the Cofactor Photoreduction.

ABSTRACT: Photolyase contains a flavin cofactor in a fully reduced form as its functional state to repair ultraviolet-damaged DNA upon blue light absorption. However, after purification, the cofactor exists in its oxidized or neutral semiquinone state. Such oxidization eliminates the repair function, but it can be reverted by photoreduction, a photoinduced process with a series of electron-transfer (ET) reactions. With femtosecond absorption spectroscopy and site-directed mutagenesis, we completely recharacterized such photoreduction dynamics in the semiquinone state. Comparing with all previous studies, we identified a new intramolecular ET pathway, determined stretched ET behaviors, refined all ET time scales, and finally evaluated the driving forces and reorganization energies for eight elementar

SUBMITTER: Liu Z 

PROVIDER: S-EPMC3985926 | biostudies-literature | 2014 Mar

REPOSITORIES: biostudies-literature