title: Potentiometric and spectroscopic studies on the copper(II) complexes of rat amylin fragments. The anchoring ability of specific non-coordinating side chains.
abstract: Copper(ii) complexes of peptides modelling the sequence of the 17-22 residues of rat amylin have been studied by potentiometric, UV-Vis, CD and ESR spectroscopic methods. The peptides were synthesized in N-terminally free forms, NH2-VRSSNN-NH2, NH2-VRSSAA-NH2, NH2-VRAANN-NH2, NH2-VRSS-NH2, NH2-SSNN-NH2, NH2-SSNA-NH2 and NH2-AANN-NH2, providing a possibility for the comparison of the metal binding abilities of the amino terminus and the -SSNN- domain. The amino terminus was the primary ligating site in all cases and the formation of only mononuclear complexes was obtained for the tetrapeptides. The thermodynamic stability of the (NH2, N(-), N(-)) coordinated complexes was, however, enhanced by the asparaginyl moiety in the case of NH2-SSNN-NH2, NH2-SSNA-NH2 and NH2-AANN-NH2. Among the hexapeptides the formation of dinuclear complexes was characteristic for NH2-VRSSNN-NH2 demonstrating the anchoring ability of the -SSNN- (SerSerAsnAsn) domain. The complexes of the heptapeptide NH2-GGHSSNN-NH2 were also studied and the data supported the above mentioned anchoring ability of the -SSNN- site.
authors.affiliation: Department of Inorganic and Analytical Chemistry, University of Debrecen, H-4010, Debrecen, Hungary. varnagy.katalin@science.unideb.hu.
authors.forename: Ágnes
authors.initials: Á
authors.lastname: Dávid
authors.forename: Csilla
authors.initials: C
authors.lastname: Kállay
authors.forename: Daniele
authors.initials: D
authors.lastname: Sanna
authors.forename: Norbert
authors.initials: N
authors.lastname: Lihi
authors.forename: Imre
authors.initials: I
authors.lastname: Sóvágó
authors.forename: Katalin
authors.initials: K
authors.lastname: Várnagy
mesh_terms: D000818:Animals; D001665:Binding Sites / Q000502:physiology; D056831:Coordination Complexes / Q000737:chemistry* / Q000378:metabolism; D003300:Copper / Q000032:analysis* / Q000737:chemistry* / Q000378:metabolism; D058228:Islet Amyloid Polypeptide / Q000032:analysis* / Q000737:chemistry* / Q000378:metabolism; D011199:Potentiometry / Q000379:methods; D051381:Rats; D013056:Spectrophotometry, Ultraviolet / Q000379:methods
chemical_list: D056831:Coordination Complexes; D058228:Islet Amyloid Polypeptide; D003300:Copper