EXPERIMENTAL AND THEORETICAL VIBRATIONAL STUDIES OF THE AMINO-ACID L-ASPARAGINE IN SOLUTION

Raman spectroscopy and the self-consistent reaction field (SCRF) theor y were used to study structural and vibrational features of the amino acid L-asparagine in H2O and D2O solutions. Ab initio methodology at t he RHF/6-31 + G level were used to evaluate the minimum energy struct ure, quadratic force field, vibrational wavenumbers and infrared inten sities of this molecule in a polar medium. Raman spectra from aqueous solutions of asparagine and its ND,+ and ND, deuterated isotopomers we re recorded and a general assignment of the measured bands was propose d on the basis of the isotopic shifts. The results were successfully s upported by a scaled 6-31 + G/SCRF quantum-mechanical force field. (C ) 1997 John Wiley & Sons, Ltd.