EPR Spectroscopy of soybean lipoxygenase-1: Description and quantification of the high-spin Fe(III) signals

摘要: The interaction of soybean lipoxygenase-1 with 13-Ls-hydroperoxy-9-cis,11-trans-octadecadienoic acid, the product enzymic dioxygenation linoleic results in formation either a yellow or purple coloured enzyme form depending on amount used. composition high-spin Fe(III) signals EPR spectra both forms has been studied and EPR-visible iron determined by integration simulation. Sets g values species building up signal around 6 are derived from third-order perturbation calculation exact numerical diagonalization spin Hamiltonian describing system. these calculations generally applicable to systems having S = 5/2. native, colourless is almost EPR-nondetectable. shows complex which consists contributions at least three different ligand symmetry. corresponds approx. 75% total content. roughly same but ratio between not as enzyme. This also an additional 4.3 large amplitude relatively low integrated intensity (approx. 10% content). consistent suggested mechanism catalytic function lipoxygenase was based qualitative (De Groot, J.J.M.C., Veldink, G.A., Vliegenthart, J.F.G., Boldingh, J., Wever, R. van Gelder, B.F. (1975) Biochim. Biophys. Acta 377, 71--79).