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

Abstract

A series of derivatives for both the arthropod [Limulus polyphemus] and mollusk (Busycon canaliculatum) hemocyanin biopolymers was prepared; the derivatives contain a small fraction of EPR-detectable half-met [Cu(II) Cu(I)] sites dispersed among the nondetectable oxy binuclear copper active sites. Upon deoxygenation, large changes in the EPR 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 by these spectral changes as the hemocyanins go from a relaxed to a tensed quaternary structure are discussed.