The nature of the nitric oxide complexes of lipoxygenase

Abstract

The NO complex of lipoxygenase with EPR signals near g = 4.0 is an S = 3/2 system with D ≈ 15 cm −1 similar to Fe 2+-EDTA-NO. This may result from antiferromagnetic coupling of axial ( D ⪢ E) high spin ferrous iron to NO. The other NO complex of lipoxygenase, with EPR signals below g e, may result from rhombic high spin ferrous iron coupled to NO with D > J. The quenching of both signals by a hydroperoxy derivative of linoleic acid probably represents replacement of NO by an oxygen ligand.