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Harry A. Frank
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NIH Postdoctoral Fellow, University of California at
Berkeley, 1977-80
Ph.D., Boston University, 1977
B.S., Memphis State University, 1972
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Our research is focusing on the important
class of biological pigments known as carotenoids. These
are long-chain, conjugated, π-electron molecules,
typified by β-carotene and lycopene, that provide
an abundance of coloration in nature.
Carotenoids are unique in that their
diversity of function is unmatched by any of the other
class of naturally-occurring pigments. In humans, carotenoids
play an important role as biological antioxidants against
many chronic health disorders. In plants, algae, and
photosynthetic bacteria, carotenoids operate efficiently
in regulating photosynthetic energy transport and in
protecting the systems from reactions with active oxygen
species. Carotenoids also inhibit harmful reactions
resulting from the photosynthetic apparatus being oversaturated
with light.
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The Roles of Carotenoids
in Photosynthesis
There are many different roles carotenoids
play in photosynthesis. These include: Light-harvesting,
photoprotection, singlet oxygen scavenging, excess energy
dissipation, protein structure stabilization, energy
flow regulation, and redox function. A major goal of
our research on carotenoids is to understand how these
molecules are able to carry out these diverse functions.
Information on the structures of carotenoids from X-ray
and electron diffraction and nuclear magnetic resonance
(NMR) techniques are being used to help pinpoint specific
molecular features that control the photochemical and
nonphotochemical processes in which carotenoids participate.
Because it is not possible to deduce the mechanisms
of the functions of carotenoids solely on the basis
of their structures, information from molecular spectroscopic
techniques that probe the dynamics and energetics of
carotenoids are needed to augment the structural data.
Hence, we are using absorption, fluorescence, fluorescence
excitation, and ultrafast transient optical spectroscopy
to elucidate the mechanisms of the reactions carotenoids
undergo. In addition to the optical studies, magnetic
resonance spectroscopy is being used in our lab to determine
the structures, geometries, identities, and dynamics
of carotenoids involved in photosynthetic energy transport
and to determine the nature of their interactions with
chlorophyll. |
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