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Raman and surface‐enhanced Raman studies of α‐aminophosphinic inhibitors of metalloenzymes
Author(s) -
Podstawka E.,
Dra̧g M.,
Oleksyszyn J.
Publication year - 2009
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.2299
Subject(s) - raman spectroscopy , chemistry , crystallography , ring (chemistry) , surface enhanced raman spectroscopy , benzene , raman scattering , aminopeptidase , molecule , substrate (aquarium) , adsorption , stereochemistry , leucine , organic chemistry , amino acid , biochemistry , physics , oceanography , optics , geology
Here, we report the nature of new di‐α‐amino (L 1 –L 3 ) and α‐amino‐α‐hydroxyphosphinic (L 4 –L 6 ) acids, which are considered potential inhibitors of the aminopeptidase N, adsorbed on a colloidal silver surface by means of surface‐enhanced Raman scattering (SERS) spectroscopy. In order to reveal the adsorption mechanism of these species from their SERS spectra, Fourier‐transform Raman (FT‐RS) spectra of these nonadsorbed molecules were measured. By examining the enhancement, shift in wavenumbers, and changes in breadth of the SERS bands due to the adsorption process, we revealed that the tilted compounds interact with the colloidal silver substrate mainly through the benzene ring, amino group, and phosphinic moiety in the following way. The benzene ring of L 2 and L 3 is ‘standing up’ on the colloidal silver surface, and the CN bond is almost vertical to it, while the tilt angle between the OPO bond and this surface is greater than 45°. On the other hand, for L 1 , L 4 , and L 5 , the aromatic ring and CN bond are arranged more or less tilted, and the tilt angle between the OPO bond and the silver substrate is smaller than 45°. The elongation of the bond to the benzene ring, the L 6 case, produces an almost horizontal orientation of the benzene ring and the OPO bond on the silver nanoparticles. For these ligands, the complement inhibition IC 50 tested in vitro using porcine kidney leucine aminopeptidase was correlated mainly with the behavior of the OPO and CCHN fragments on the silver surface. Copyright © 2009 John Wiley & Sons, Ltd.