Vibrational Spectroscopic Analysis of L,D-Dipeptides |
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Authors: | Vaman M. Naik Indrin Chetty † |
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Affiliation: | Department of Natural Sciences , The University of Michigan-Dearborn , Dearborn, MI, 48128, USA |
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Abstract: | Raman and infrared spectra of Boc-D-Leu-L-Leu-OMe, Boc-L-Ile-D-aIle-OMe and its N-deuterated derivative have been obtained. Normal mode frequencies on the models of these dipeptides have been calculated and the conformationally sensitive amide I, II, III and V modes are compared with the experimentally observed frequencies. The calculated frequencies are in good agreement with the observed frequencies. It is observed that the amide frequencies in these dipeptides are not very sensitive to their backbone conformation. This is in contrast to the well established conformational dependence of the amide modes in peptides, polypeptides and proteins. The normal mode calculations on these peptides also show absence of mixing in amide I and II modes, and hence lack of appreciable splitting in these modes due to transition dipole coupling. |
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Keywords: | Raman spectra IR spectra Boc-(D-Leu-L-Leu)-OMe Boc-(L-Ile-D-alle)-OMe amide modes vibrational assignment |
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