Res. Chem. Intermed.
, Vol. 28, No. 7–9, pp. 795–815 (2002)
Also available online - www.vsppub.com
Photoinduced charge transfer in helical polypeptides
VALENTINE I. VULLEV
and GUILFORD JONES, II
Department of Chemistry and the Photonics Center, Boston University, Boston MA 02215, USA
Abstract—Investigation of electron transfer in synthetic polypeptides provides an important probe
of how charge entrainment is mediated in redox-active proteins, including photosynthetic reaction
centers. Interest in this eld has focused increasingly on experimental probes of photoinducedelectron
transfer kinetics and thermodynamics, and the in uence of various features of polypeptide templates
(e.g. the hydrogen bonding network, the permanent dipole moment for ®-helices) that assemble redox
groups for long range charge transfer. A review of the various approaches is presented here with
attention to heliogenic peptides and the mediation of photoinduced charge entrainment.
In natural light-harvesting systems, the initial transduction of absorbed radiation en-
ergy into charge ow is attained via photoinduced electron transfer. Gaining insight
into how charge entrainment is mediated in protein or polypeptide environments is
important, not only for a deeper mechanistic understanding of the light cycle of pho-
tosynthesis, but also for better comprehension of processes involved in other natural
redox systems. For two decades research interest in electron transfer in photoactive
polypeptides has been steadily growing (for reviews see [1–3]), largely in uenced
by the capabilities of peptides to adopt well ordered secondary and tertiary struc-
The photosynthetic reaction center (RC) is the most vital component of the light
harvesting apparatus of higher plants and numerous microorganisms. It is where
light energy is converted into the energy of charge-separated states and where
electron entrainment is initiated. There are two main approaches in photosynthesis
research: (1) a direct study of the various natural photosynthetic reaction centers and
To whom correspondence should be addressed.
Present address: Department of Chemistry and Chemical Biology, Harvard University,Cambridge,
MA 02138, USA.