title: Modeling of fluorescence quenching by lutein in the plant light-harvesting complex LHCII.
abstract: Photoprotective non-photochemical quenching (NPQ) in higher plants is the result of the formation of energy quenching traps in the light-harvesting antenna of photosystem II (PSII). It has been proposed that this quenching trap is a lutein molecule closely associated with the chlorophyll terminal emitter of the major light-harvesting complex LHCII. We have used a combination of time-dependent density functional theory (TD-DFT) and the semiempirical MNDO-CAS-CI method to model the chlorophyll-lutein energy transfer dynamics of the highly quenched crystal structure of LHCII. Our calculations reveal that the incoherent "hopping" of energy from Chla612 to the short-lived, dipole forbidden 2(1)A(g)(-) state of lutein620 accounts for the strong fluorescence quenching observed in these crystals. This adds weight to the argument that the same dissipative pathway is responsible for in vivo NPQ.
authors.affiliation: The School of Biological and Chemical Sciences, Queen Mary, University of London , Mile End Road, London E1 4NS, U.K.
authors.forename: C D P
authors.initials: CD
authors.lastname: Duffy
authors.forename: J
authors.initials: J
authors.lastname: Chmeliov
authors.forename: M
authors.initials: M
authors.lastname: Macernis
authors.forename: J
authors.initials: J
authors.lastname: Sulskus
authors.forename: L
authors.initials: L
authors.lastname: Valkunas
authors.forename: A V
authors.initials: AV
authors.lastname: Ruban