Active site chemistry of lysyl oxidase.

The bimolecular reduction of the Cu(II)-based enzyme lysyl oxidase with two inorganic reductants, tris bipyridylchromium(II) and (1,3,6,8,10,13,16,19)-octaazabicyclo (6,6,6)eicosanecobalt(II) has been examined at various ionic strength and [H+] conditions. The electrochemical properties of the enzyme have also been examined. The results show that Cu(II) is the redox site in the enzyme and has E 1/2 = 0.05 +/- 0.005 V against SCE. The observed rate constants, kobs, for the reduction of the enzyme by either Cr(bpy)32+ or Co(sep)2+ at any concentration of the reductant increased with the ionic strength of the medium. The ionic strength dependence of kobs has been analyzed in terms of the charge of the active site being 1 +.