Impact of the N5-proximal Asn on the thermodynamic and kinetic stability of the semiquinone radical in photolyase.

ABSTRACT: Flavoproteins can dramatically adjust the thermodynamics and kinetics of electron transfer at their flavin cofactor. A versatile regulatory tool is proton transfer. Here, we demonstrate the significance of proton-coupled electron transfer to redox tuning and semiquinone (sq) stability in photolyases (PLs) and cryptochromes (CRYs). These light-responsive proteins share homologous overall architectures and FAD-binding pockets, yet they have evolved divergent functions that include DNA repair, photomorphogenesis, regulation of circadian rhythm, and magnetoreception. We report the first measurement of both FAD redox potentials for cyclobutane pyrimidine dimer PL (CPD-PL, Anacystis nidulans). These values, E(1)(hq/sq) = -140 mV and E(2)(sq/ox) = -219 mV, where hq is FAD hydroquinone and ox is o

SUBMITTER: Damiani MJ 

PROVIDER: S-EPMC3039355 | biostudies-literature | 2011 Feb

REPOSITORIES: biostudies-literature