Ultrafast Dynamics of Resonance Energy Transfer in Cryptochrome

摘要

Cryptochrome,a recently discovered blue-light photoreceptor,synchronizes the circadian rhythm in animals and regulates growth and development in plants.It is highly homologous to photolyase in sequence,a well-studied photoenzyme for repairing damaged DNA.Both are flavoproteins containing two noncovalently bound chromophores.One chromophore is a flavin-adenine dinucleotide (FAD) as a key cofactor to carry out initial biological function upon photoexcitation,and the other is a pterin in the form of meth-enyltetrahydrofolate (MTHF) as a light-harvesting antenna to enhance biological efficiency.In vivo,it is believed that in both proteins the flavin is in the fully reduced FADH~_ form,but during purification,it is oxidized to FADH or FAD.The resonance energy transfer from MTHF to both FADH and FADH~- in Escherichia coli photolyase has been well characterized.