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Arg side-chain-backbone interactions evidenced in model peptides by 17O-NMR spectroscopy
V Tsikaris1, A Troganis, V Moussis
1Department of Chemistry, Section of Organic Chemistry and Biochemistry, University of Ioannina, 451 10 Ioannina, Greece. btsikari@cc.uoi.gr
Abstract:
The guanidinium group of arginine possesses a variety of biochemical functions, either by participating in direct interactions in recognition processes, or by stabilizing secondary structures. Three model compounds, selectively (17)O enriched, Ac-Arg-Ala-[(17)O]Pro-NH(2) (1), Piv-Arg-Pro-[(17)O]Gly-NH(2) (2) (C-terminal segment of the luteinizing hormone releasing hormone), and Piv-Nle-Pro-[(17)O]Gly-NH(2) (3), were prepared and studied by (17)O-nmr spectroscopy. A direct hydrogen-bonded interaction between the Arg side chain and the carbonyl main chain carboxy-terminus was found, thus confirming the tendency of Arg to participate in proton-acceptor functions.