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Experimental and theoretical Raman and surface‐enhanced Raman scattering study of cysteine
Author(s) -
Diaz Fleming Guillermo,
Finnerty Justin J.,
CamposVallette Marcelo,
Célis Freddy,
Aliaga Alvaro E.,
Fredes Carlos,
Koch Rainer
Publication year - 2009
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.2175
Subject(s) - raman spectroscopy , raman scattering , cysteine , materials science , x ray raman scattering , chemistry , optics , physics , biochemistry , enzyme
Abstract Raman spectra in solid and 1 M solution of L ‐cysteine and surface‐enhanced Raman scattering (SERS) spectra of this molecule in the zwitterionic form, by using colloidal silver nanoparticles, have been recorded. Density functional theory with the B3LYP functional was used for the optimizations of the ground state geometries and simulation of the vibrational spectrum of this amino acid. The SERS spectrum with a large silver cluster as a model metallic surface was simulated for the first time. Taking into account the experimental and calculated Raman and SERS vibrations and the corresponding assignments, as well as a comparison of force constants and geometrical parameters between the free zwitterion cysteine and the one in the presence of the colloidal silver nanoparticles, we can confirm the presence of gauche (P H ) and trans (P N ) rotamers in the solid state, the formation of a SS bond in the solution state, the dissociation of the peptide bond and mixing of rotamers because of the SERS effect, and the relative importance of the interaction of sulphyldryl, NH 3 + , and carboxylate groups with the metallic surface. Copyright © 2009 John Wiley & Sons, Ltd.