title: Copper(II) complexes of Neobelliera Bullata Trypsin Modulating Oostatic Factor and its analogues.
abstract: The stoichiometry, stability constants and solution structure of the complexes formed in the reaction of copper(II) with hexapeptide NPTNLH, i.e. the Neobelliera Bullata Trypsin Modulating Oostatic Factor (Neb-TMOF), and its analogues DPTNLH, Ac-NPTNLH and Ac-DPTNLH have been determined by potentiometric, UV-visible, CD and EPR spectroscopic methods. Upon raising pH for Ac-NPTNLH and Ac-DPTNLH peptides, copper(II) coordination starts from the imidazole nitrogen of the His(6); afterwards three deprotonated amide nitrogens are progressively involved in metal ions coordination. In a wide pH range of 4.5-8.5 for the NPTNLH and DPTNLH ligands the CuL complex dominates with the imidazole nitrogen of His(6) coordinated to form a macrochelate. The N-terminal amino group of the NPTNLH and DPTNLH peptides takes part in the coordination of the metal ion in the CuL, CuH(-1)L and CuH(-2)L complexes. However, at pH above 9 the CuH(-3)L complex with the {N(Im),3N(-)} coordination mode is formed. For the CuH(-2)L complex the spectroscopic data clearly indicate the 4N {NH(2), CO or COO(-), 2N(-), N(Im)} bonding mode with the axial coordination of the N-terminal amine group to the metal ion.
authors.affiliation: Faculty of Chemistry, University of Wrocław, Joliot-Curie 14, 50-383 Wroclaw, Poland. TerKow@wchuwr.chem.uni.wroc.pl
authors.forename: Teresa
authors.initials: T
authors.lastname: Kowalik-Jankowska
authors.forename: Lukasz
authors.initials: L
authors.lastname: Biega
authors.forename: Mariola
authors.initials: M
authors.lastname: Kuczer
authors.forename: Danuta
authors.initials: D
authors.lastname: Konopińska
mesh_terms: D003300:Copper / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007301:Insect Hormones / Q000737:chemistry*; D008024:Ligands; D015394:Molecular Structure; D009842:Oligopeptides / Q000737:chemistry*; D009942:Organometallic Compounds; D011199:Potentiometry; D013057:Spectrum Analysis
chemical_list: D007301:Insect Hormones; D008024:Ligands; D009842:Oligopeptides; D009942:Organometallic Compounds; C094891:prothoracicostatic hormone, Neobellieria bullata; D003300:Copper