Sum rules and determination of exciton coupling using absorption and circular dichroism spectra of biological polymers
- aDepartment of Chemistry, Tulane University, New Orleans LA 70118; and
- bDepartment of Chemistry, Northwestern University, Evanston IL 60208
-
Edited by George C. Schatz, Northwestern University, Evanston, IL, and approved November 25, 2008 (received for review August 27, 2008)
Abstract
Optical spectra of biological polymers contain important information about their structure and function in living organisms. This information can be accessed by extracting an optical interaction of monomers, i.e., their exciton coupling, from experimental data. This coupling is sensitive to molecular structure, geometry, and conformation and can be used to characterize them. However, the accurate determination of exciton coupling in important biological molecules is difficult because inhomogeneous broadening smears out the monomer interaction. We suggest a way to overcome this problem by applying exact sum rules. These sum rules are derived by establishing a straightforward relationship between integral characteristics of absorption and circular dicroism spectra, and exciton coupling. Exciton coupling between AT pairs in native DNA conformation is estimated by applying these sum rules to DNA hairpin optical spectra as V0 ∼ 0.035 eV in agreement with the earlier numerical calculations.
Footnotes
- 1To whom correspondence should be addressed. E-mail: aburin{at}tulane.edu
-
Author contributions: A.L.B. designed research; A.L.B., M.H., and F.D.L. performed research; A.L.B., M.E.A., M.H., and F.D.L. analyzed data; and A.L.B. wrote the paper.
-
The authors declare no conflict of interest.
-
This article is a PNAS Direct Submission.
- © 2009 by The National Academy of Sciences of the USA
