title: Determination of a binding site of Cu and Ni metal ions with oxytocin peptide by electrospray tandem mass spectrometry and multiple mass spectrometry.
abstract: The structures of a [Ni(II), Cu(II)- - -oxytocin] complex were investigated by electrospray ionization-mass spectrometry in positive mode. The fragmentation patterns of the [Ni(II), Cu(II) + OT](2+) complex were analyzed by tandem mass spectrometry and multiple mass spectrometry in the gas-phase. Conformations of metalII ion binding to oxytocin (OT) have been studied to explain the biological activity difference in the physiological solution. The [Ni(II) + OT](2+) and [Cu(II) + OT](2+) complexes were observed as the main ions in MS spectra. The Cys1-Tyr2-Ile3-Gln4 sequence of oxytocin is suggested to be a binding site for the [Ni(II) + OT](2+) gas-phase complex and Ile3-Gln4-Asn5-Cys6 sequence for the [Cu(II) + OT](2+) gas-phase complex. The specific binding site of CuII ion in the [Cu(II) + OT](2+) complex is explained as a reason of the negligible effect on the [Cu(II)- - -oxytocin] biological activity in aqueous solution.
authors.affiliation: Department of Applied Chemistry, Kumoh National Institute of Technology, 1 Yangho-Dong, Gumi 730-701, Republic of Korea.
authors.forename: Hye-Jin
authors.initials: HJ
authors.lastname: Jeong
authors.forename: Ho-Tae
authors.initials: HT
authors.lastname: Kim
mesh_terms: D001665:Binding Sites; D002413:Cations, Divalent; D003300:Copper / Q000737:chemistry / Q000378:metabolism; D015394:Molecular Structure; D009532:Nickel / Q000737:chemistry / Q000378:metabolism; D010121:Oxytocin / Q000737:chemistry* / Q000378:metabolism; D012996:Solutions; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry; D014867:Water
chemical_list: D002413:Cations, Divalent; D012996:Solutions; D014867:Water; D010121:Oxytocin; D003300:Copper; D009532:Nickel