... perturbation of the electronic absorbanceproperties of the chromophore without affecting the coordination number or the spin state of the haem-iron, and the quenching of the 1H-NMR relaxivity. Values of Kdfor ... affect the coordinationstate of haem iron (see Fig. 2), His242 does not appear to bea likely candidate for the axial haem bonding.CONCLUSIONS The effect of ibuprofen and warfarin on the electronicabsorption ... advantage of electronic absorption spectroscopy,EPR spectroscopy and 1H-NMR relaxometry [7,8,10,21,22].Here, the effect of ibuprofen and warfarin on the electronicabsorption spectroscopic and 1H-NMR-relaxometric...