Preparation of a spectral probe derivative of the hemocyanin biopolymer: effects of allosteric interactions on the coupled binuclear copper active site.

A series of derivatives for both the arthropod and mollusc hemocyanin biopolymers has been prepared; the derivatives contain a small fraction of electron paramagnetic resonance-detectable half-met [Cu(II) CU(I)] sites dispersed among the non-detectable oxy binuclear copper active sites. Upon deoxygenation, large changes in the electron paramagnetic resonance signal of these half-met spectral probe derivatives are observed, which are further adjusted by the heterotropic effectors Ca2+ and H+. The active site structural changes indicated that these spectral changes as the hemocyanins go from a relaxed to a tensed quaternary structure are then discussed.