title: Binding study of metal ions to S100 protein: 43Ca, 25Mg, 67Zn and 39K n.m.r.
abstract: The interactions of the S100 protein (S100) with metal cations such as Ca2+, Mg2+, Zn2+ and K+ were studied by the metal n.m.r. spectroscopy. The line widths of 43Ca, 25Mg, 67Zn and 39K n.m.r. markedly increased by adding all S100s. A broad 43Ca n.m.r. band of Ca(2+)-S100a solution was not affected by Zn2+ and K+, while it was greatly decreased by adding Mg2+. The 43Ca n.m.r. spectra of Ca(2+)-S100a0 and -S100b solutions consisted of two slow-exchangeable signals which corresponded to Ca2+ bound to two environmentally different sites of the S100a0. These two 43Ca n.m.r. signals were not affected by Zn2+ and K+. The line width of broad 25Mg n.m.r. band of the Mg(2+)-S100 solution greatly decreased by adding Ca2+, while it did not change by adding Zn2+ and K+. Further, the addition of Ca2+, Mg2+ and K+ did not affect the line width of the 67Zn n.m.r. of the Zn(2+)-S100 solutions. These findings suggest that: (1) Mg2+ binds to all S100s, and at least one of the Mg2+ binding sites of S100 molecule is the same as the Ca2+ binding site; (2) Zn2+ binds to S100s, although the binding site(s) is/are different from Ca(2+)- or Mg(2+)-binding site(s), and the environment of Zn2+ nuclei will not change even though Ca2+ binds to S100s.
authors.affiliation: Department of Functional Polymer Science, Faculty of Textile Science and Technology, Shinshu University, Ueda, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Ogoma
authors.forename: H
authors.initials: H
authors.lastname: Kobayashi
authors.forename: T
authors.initials: T
authors.lastname: Fujii
authors.forename: Y
authors.initials: Y
authors.lastname: Kondo
authors.forename: A
authors.initials: A
authors.lastname: Hachimori
authors.forename: T
authors.initials: T
authors.lastname: Shimizu
authors.forename: M
authors.initials: M
authors.lastname: Hatano
mesh_terms: D000818:Animals; D001665:Binding Sites; D001921:Brain / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D007477:Ions; D008274:Magnesium / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008670:Metals / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism; D013552:Swine; D015032:Zinc / Q000378:metabolism
chemical_list: D002135:Calcium-Binding Proteins; D007477:Ions; D008670:Metals; D008274:Magnesium; D015032:Zinc; D011188:Potassium; D002118:Calcium