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Structural properties of bombesin‐like peptides revealed by surface‐enhanced Raman scattering on roughened silver electrodes
Author(s) -
Podstawka Edyta
Publication year - 2008
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.21047
Subject(s) - chemistry , raman spectroscopy , electrode , raman scattering , crystallography , fourier transform infrared spectroscopy , analytical chemistry (journal) , stereochemistry , organic chemistry , chemical engineering , physics , optics , engineering
Abstract This work presents a Fourier‐transform absorption infrared, Fourier‐transform Raman, and surface‐enhanced Raman scattering (SERS) study of the following peptides belonging to the bombesin‐like family: phyllolitorin, [Leu 8 ]phyllolitorin, NMB, NMC, and PG‐L. The SERS study was undertaken to understand the adsorption mechanism of bombesin‐like peptides on an electrochemically roughened silver electrode surface and to show changes in the adsorption mechanism with alterations in amino acids and small tertiary structures. The SERS spectra presented here shows bands mainly associated with the Trp 8 residue vibrations. The presence of mainly pyrrole coring vibrations for phyllolitorin and [Leu 8 ]phyllolitorin and mainly benzene coring modes for NMB and NMC indicated that these groups interact with the roughened silver electrode surface. Furthermore, N 1 C 8 and C 3 C 9 bonds of the PG‐L indole ring seemed to have nearly a vertical orientation on the electrode surface. In addition, distinct vibrations of the CS fragment were observed in the SERS spectra of [Leu 8 ]phyllolitorin and PG‐L. The strong enhancement of the ν(CO) vibration in the [Leu 8 ]phyllolitorin SERS spectrum yielded evidence that the intact CO bond(s) bind strongly to the silver electrode surface, whereas NMC, phyllolitorin, and NMB were located near the silver surface. This finding was supported by the presence of the ν(CC O ) mode. The amide I band observed at 1642 and 1634 cm −1 for NMB and NMC, respectively, and the Raman amide III band seen in the 1282–1249 cm −1 range for all peptides except PG‐L, indicate that the strongly hydrogen‐bonded α‐helical conformation and random‐coil structure are favored for binding to the surface. © 2008 Wiley Periodicals, Inc. Biopolymers 89: 980–992, 2008. This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com