title: The effect of some anions on the spectral properties of bovine ceruloplasmin.
abstract: The effect of binding of N3-, SCN-, OCN-, and F- to bovine ceruloplasmin (Cp) has been studied in detail using absorption, circular dichroic (CD), and electron paramagnetic resonance (EPR) spectroscopies. With the addition of increasing amounts of N3-, SCN-, and OCN- to a Cp solution, the intensity of the band at 614 nm at first increased several percent and then decreased gradually as at least one type I copper was reduced and/or as the type I copper was changed to type II copper. Concomitantly, new bands appeared at 430 and 365 nm for N3-, 435 and 380 nm for SCN-, and about 390 nm for OCN-. A conformational change in the protein induced by the binding of N3-, SCN-, and OCN- to the type II and type III coppers led to the change in the CD spectra. The observed increase of the band at about 430 nm was attributed to the change occurring at the type I copper site. On the other hand, the band at about 370 nm may come from a charge transfer of coordinated anions to the Cu(II) ion. Fluoride ion did not induce the appearance of the band at around 430 and 370 nm, but the parallel component of the type II copper EPR signal was split upon the binding of two fluoride ions to the copper ion.
mesh_terms: D000818:Animals; D000838:Anions; D002417:Cattle; D002570:Ceruloplasmin / Q000378:metabolism*; D002942:Circular Dichroism; D004578:Electron Spin Resonance Spectroscopy; D011485:Protein Binding; D011487:Protein Conformation
chemical_list: D000838:Anions; D002570:Ceruloplasmin