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Structure and conformation of Arg 8 vasopressin modified analogs
Author(s) -
PodstawkaProniewicz Edyta,
Sobolewski Dariusz,
Prahl Adam,
Kim Younkyoo,
Proniewicz Leonard M.
Publication year - 2012
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.2986
Subject(s) - chemistry , raman spectroscopy , raman scattering , crystallography , molecule , colloid , aqueous solution , inorganic chemistry , analytical chemistry (journal) , organic chemistry , physics , optics
Fourier‐transform Raman and infrared spectra were acquired for four arginine vasopressin (AVP) analogs containing L ‐diphenylalanine (Dpa): [Dpa 2 ]AVP, [Cpa 1 ,Dpa 2 ]AVP, [Dpa 3 ]AVP, and [Cpa 1 ,Dpa 3 ]AVP (where Cpa denotes 1‐mercaptocyclohexaneacetic acid). We compared and analyzed these spectra. In addition, the Raman spectra were compared to the corresponding surface‐enhanced Raman scattering spectra recorded in an aqueous silver colloidal dispersion. Silver colloidal dispersions prepared by the simple borohydride reduction of silver nitrate were used as substrates. The geometry of these molecules etched on the silver surface was deduced from the observed changes in the intensity enhancement, breadth, and shift in wavenumber of the Raman bands in the spectra of the bound versus free species. Based on the obtained data, adsorption mechanisms were proposed for each case, and the suggested adsorbate structures were compared. All the molecules were thought to adsorb onto a silver surface via a phenyl ring, free electron pairs on the sulfur atom, and CO and CONH‐bonds. However, the orientation of these fragments on the colloidal silver surface and the strength of the interactions with this surface are different. For [Dpa 3 ]AVP and [Cpa 1 ,Dpa 3 ]AVP, a strong interaction among the—CCN‐peptide fragment and the colloidal silver surface occurs. Copyright © 2011 John Wiley & Sons, Ltd.