VIBRATIONAL FREQUENCIES OF CYSTEINE AND SERINE ZWITTERIONS - AN AB-INITIO ASSIGNMENT

The vibrational frequencies of cysteine and serine zwitterions are eva luated using ab initio methods at the 4-31G level. The calculated fre quencies along with the corresponding potential energy distributions a re used to assign the IR and Raman spectra of the zwitterions of L-cys teine and D,L-serine. The calculated Raman activities, IR intensities along with the experimental Raman optical activities of these amino ac ids are used as aids in the assignments. The similarities and differen ces between the spectra of these amino acids are highlighted.