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Light‐generated Paramagnetic Intermediates in BLUF Domains †
Author(s) -
Weber Stefan,
Schroeder Claudia,
Kacprzak Sylwia,
Mathes Tilo,
Kowalczyk Radoslaw M.,
Essen LarsOliver,
Hegemann Peter,
Schleicher Erik,
Bittl Robert
Publication year - 2011
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.2010.00885.x
Subject(s) - flavin group , flavoprotein , rhodobacter sphaeroides , cofactor , chemistry , flavin adenine dinucleotide , photochemistry , photolyase , electron paramagnetic resonance , biochemistry , nuclear magnetic resonance , dna , enzyme , photosynthesis , physics , dna repair
Blue‐light sensitive photoreceptory BLUF domains are flavoproteins, which regulate various, mostly stress‐related processes in bacteria and eukaryotes. The photoreactivity of the flavin adenine dinucleotide (FAD) cofactor in three BLUF domains from Rhodobacter sphaeroides , Synechocystis sp . PCC 6803 and Escherichia coli have been studied at low temperature using time‐resolved electron paramagnetic resonance. Photoinduced flavin triplet states and radical‐pair species have been detected on a microsecond time scale. Differences in the electronic structures of the FAD cofactors as reflected by altered zero‐field splitting parameters of the triplet states could be correlated with changes in the amino‐acid composition of the various BLUF domains’ cofactor binding pockets. For the generation of the light‐induced, spin‐correlated radical‐pair species in the BLUF domain from Synechocystis sp. PCC 6803, a tyrosine residue near the flavin’s isoalloxazine moiety plays a critical role.