Effects of anions, Ca2+, Mg2+, and aliphatic alcohols on the reaction of hemocyanin with cyanide.

The reaction between Carcinus maenas hemocyanin and cyanide has been used for probing protein conformation in the presence of perturbants such as various anions, cations (Ca2+, Mg2+), and aliphatic alcohols. The kinetic parameters of the reaction are strongly affected by these agents, suggesting that the induced conformational modifications change the reactivity of the active site toward exogenous ligands. Different patterns are observed according to the perturbant used. As indicated by the mathematical treatment of the kinetic curves the affinity of the active site for CN- and O2 is affected much more than the rate constant of copper removal.