Binuclear Electron-Paramagnetic-Resonance Signals of Arthropodan Methaemocyanins in the Presence of Nitrite
The deoxy- and oxyderivatives of haemocyanin are diamagnetic; in the oxyderivative the copper(II) ions in the binuclear copper site are strongly magnetically coupled. A strong interaction between the two copper(II) ions in a copper pair is favoured when only very few atoms form a superexchange pathway leading to a coupling of the unpaired spins. The copper(II) ions can also be magnetically coupled as a function of their distance and thus give rise in electron paramagnetic resonance (EPR) to a broad triplet signal near g = 2 and a weakly allowed signal at half field near g = 4, as observed for Helix pomatia methaemocyanin with acetate at pH 5.7 (1, 2).
KeywordsNitrogen Monoxide Electron Paramagnetic Resonance Electron Paramagnetic Resonance Spectrum Electron Paramagnetic Resonance Signal Receiver Gain
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