Copper(II) Schiff-base complexes and apoglobin stability

N,N'-Propylene-bis-(N-salicylidene)copper(Cu(Salprn)) explicitly stabilizes apomyoglobin. The optical spectrum of this copper(II) Schiff-base complex of apomyoglobin arises from the electronic excitations of pi*-O-Salprn-->dx (2)-y(2) and N-Salprn-->dx(2)-y(2). Shifts of these transitions with respec t to those of the parent complex may be;a consequence of hydrophobic solvat ochromism or binding of an additional ligand. ESR parameters imply no chang e in the identity of the first coordination sphere around the copper, while hydrophobic solvatochromism cannot be excluded. Combination of copper(II) Schiff-base complex with apomyoglobin does not inhibit the ability of apomy oglobin to extract hemin from the main component of Glycera dibranchiata he moglobin Hemin replaces the copper complex, and the value of the apparent f irst-order rate constant varies with time. The mechanism involves dissociat ive and associative interchange pathways. Values of rate constants for tran sfer of hemin to copper(II) Schiff-base apomyoglobin complex, as well as th e change of concentration with time are evaluated. (C) 1999 Elsevier Scienc e Inc. All rights reserved.