A comparison of aqueous solvent models used in the calculation
of the Raman and ROA spectra of L-alanine

K.J. Jalkanen^a,* , R.M. Nieminen^a , K. Frimand^b , J. Bohr^b , H. Bohr^b , R.C. Wade ^c,1 , E. Tajkhorshid ^d,2 , S. Suhai ^d

a Laboratory of Physics, Helsinki University of Technology, P.O. Box 1100, Otakaari 1 M, FIN-02015 HUT, Finland
b Department of Pysics, The Technical University of Denmark, DK-2800 Lyngby, Denmark
c European Molecular Biology Laboratory, Postfach 10.2209, Meyerhofstr. 1, D-69012 Heidelberg, Germany
d Department of Molecular Biophysics, German Cancer Research Center, Im Neuenheimer Feld 280, D-69120 Heidelberg, Germany

Received 4 September 2000

Abstract
This paper presents a quantum description of L-alanine in aqueous solution predicting the Raman and Raman optical activity (ROA) spectra.
We have investigated theoretically the chiral sensitive spectroscopic method of ROA as a probe for secondary structural features.
We have utilized the Becke 3LYP/6-31G* description to determine the geometries and Hessians [Theoretical and Computational Genome
Research, Plenum Press, New York, 1997, p. 225; J. Phys. Chem. B 102 (1998) 5899; Chem. Phys. 225 (2000) 165], and have calculated
the Becke 3LYP/6-31G* level electric dipole-electric quadrupole polarizability derivatives further required to obtain the ROA spectra
have also been calculated. The Raman scattering and ROA spectral simulations for the various structures are compared with the
experimentally measured spectra and previously reported spectral simulations. The combination of Raman and ROA spectroscopy is
shown to be as sensitive to secondary structural changes as its sister combination of vibrational absorption and vibrational circular
dichroism and thus offers a complementary source of information when investigating the secondary structural and chiral features of biomolecules.

* Corresponding author. Present address:
Steinbeis-Transferzentrum Genominformatik, Im Neuenheimer Feld 370/42, 69120 Heidelberg, Germany
E-mail address: kjj@hugo.hut.fi (K.J. Jalkanen)

1 Present address:
European Media Laboratory, Schloss-Wolfsbrunnenweg 33, D-69118 Heidelberg, Germany
2 Present address:
Theoretical Biophysics Group, Beckman Institute for Advanced Science and Technology,
405 N. Mathews, Urbana, IL 61801, USA.

Chemical Physics 265 (2001) 125-151