Infrared Spectroscopic Study of $C_7$ Intramolecular Hydrogen Bonds in Peptides

Rao, Pulla and Balaram, P and Rao, CNR (1983) Infrared Spectroscopic Study of $C_7$ Intramolecular Hydrogen Bonds in Peptides. In: Biopolymers, 22 (9). pp. 2091-2104.

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Abstract

The ir-spectra in the N-H stretching region of Piv-Pro-NHMe and Boc-Pro-NHMe have been studied in carbon tetrachloride and chloroform solutions over a wide range of concentrations. Based on the concentration dependence of the N-H stretching bands, it has been shown that the characteristic N-H stretching band due to the $C_7$ intramolecular hydrogen bond is around 3335 ${cm}^{-1}$. Intermolecular hydrogen bonding also occurs to a small extent in these peptides, giving rise to a slight concentration dependence of the N-H stretching bands. The band around 3335 ${cm}^{-1}$ need not necessarily be due to $C_7$ hydrogen bonds alone as proposed by Tsuboi et al. or to intermolecular hydrogen bonding alone as proposed by Maxfield et al.; this conclusion is supported by studies on Boc-Leu-NHMe, which undergoes only intermolecular hydrogen bonding We have shown that Z-Aib-Aib-OMe and Z-Aib-Ala-OMe form $C_7$ intramolecular hydrogen bonds in addition to $C_5$ intramolecular hydrogen bonds. The present studies also show that all the peptides studied exist in more than one conformation in solution.

Item Type:	Journal Article
Additional Information:	Copyright for this article belongs to John Wiley & Sons, Inc.
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	15 Mar 2005
Last Modified:	19 Sep 2010 04:18
URI:	http://eprints.iisc.ernet.in/id/eprint/2901

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