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Peptide Chirality Sensing by a Cyclodextrin–Polythiophene Conjugate
Author(s) -
Fukuhara Gaku,
Inoue Yoshihisa
Publication year - 2012
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201201294
Subject(s) - chemistry , enantiomer , circular dichroism , chirality (physics) , polythiophene , cyclodextrin , aqueous solution , dipeptide , conjugate , stereochemistry , cotton effect , peptide , crystallography , organic chemistry , polymer , conductive polymer , mathematical analysis , biochemistry , chiral symmetry breaking , physics , mathematics , quantum mechanics , nambu–jona lasinio model , quark
A new cyclodextrin–polythiophene conjugate ( CDPT ) has been prepared by attaching permethyl‐α‐cyclodextrins to polythiophene (PT) through a hexamethylene tether. Circular dichroism spectral examination of CDPT revealed that only a weak positive Cotton effect (Δ ε =0.1 M −1 cm −1 ) was induced at the main band of the PT in dimethyl sulfoxide and similarly weak bisignate signals in pure and aqueous methanol solutions, which indicates that the α‐cyclodextrins appended to PT with a long tether are ineffective in inducing a homochiral structure in the PT backbone. Nevertheless, enantiomeric amino acids and dipeptides added to an aqueous methanolic solution of CDPT caused chirality‐dependent hypochromic changes in the UV/Vis spectra, which enabled us to sense these species and quantitatively determine the enantioselectivity by observing the difference in absorbance upon interaction with pairs of enantiomers. Enantiomeric d,d / l,l ‐dipeptide pairs rather than D / L ‐amino acid pairs were better differentiated in general, the highest dd / ll selectivity of 13.7 being observed for Phe‐Phe.