H-1-Nmr Studies on Arginine Tripeptides - Evidence for Guanidinium C-Terminal Carboxylate Interactions
(EN)
Tsikaris, V.
(EN)
Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας
(EL)
Tsikaris, V.
(EN)
Guanidinium-C -terminal carboxylate interactions are involved in the establishment of the secondary structure of various biologically active peptide sequences. The conformational properties of a series of arginine-containing tripeptides, L-Arg-X-Gly (X = L-Ala, Val, Leu), in DMSO solutions at physiological pH, have been studied by means of 1D and 2D H-1-NMR spectroscopy. Measurements of the chemical shifts, NOE effects and temperature coefficients showed that the ArgN(epsilon)H and ArgN(eta)H-2 groups form two hydrogen bonds with the C-terminal carboxylate moiety, whereas the ArgN(alpha)-terminal nitrogen is in the amino state. Our results point out the significant contribution of the C-terminal carboxylate group, at physiological pH, in the stabilization of the Arg side-chain structure in peptides simultaneously containing arginine residues and carboxy terminal sequences.
(EN)
