Pb. Lukins, Single-molecule electron tunneling spectroscopy of the higher plant light-harvesting complex LHC II, BIOC BIOP R, 256(2), 1999, pp. 288-292
Citations number
26
Categorie Soggetti
Biochemistry & Biophysics
Journal title
BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS
Electronic spectroscopy of a single biological molecule is demonstrated wit
h similar to 4 Angstrom spatial resolution. The light-harvesting complex II
(LHC II), in the ground and photo-excited states, was studied using scanni
ng tunneling microscopy and spectroscopy of intact Photosystem II complexes
, analysis of the spectra indicates that the main mechanisms of tunneling b
etween the STM tip and the surface involve delocalized electronic states of
the LHC II and local vibronic states associated with C=C, C=O, C-H, N-H, a
nd O-H groups near the LHC II surface. Conduction within the bulk LHC II is
then due to ohmic and hopping conduction as well as tunneling between amin
o acid residues. Light activation of LHC II occurs via a photoconductive ra
ther than a photovoltaic mechanism. There is a dramatic light-induced incre
ase in the electronic density of states indicating a light-induced enhancem
ent of energy and electron delocalization which is important for the effici
ent and rapid transfer of excitation energy from LHC II to the Photosystem
II reaction center. (C) 1999 Academic Press.