Preparation and spectroscopic studies of cobalt(II)-substituted cucumber basic blue protein "plantacyanin"

The cobalt(II) derivative of cucumber basic blue copper protein "plantacyanin" has been prepared. The visible absorption, circular dichroic and magnetic circular dichroic spectra of Co(II)-plantacyanin are similar to those of Co(II)-plastocyanin, indicating that the stereochemistry of Co(II) is tetrahedral and at least one cysteinyl ligand around Co(II) ion is responsible for the strong charge transfer bands at 331 and ca. 390 nm.