Studies of cyanide binding to myeloperoxidase by electron paramagnetic resonance and magnetic circular dichroism spectroscopies

摘要: Abstract The techniques of magnetic circular dichroism (MCD) and absorbance spectroscopy have been used to monitor titrations oxidized myeloperoxidase with CN − , at room temperature, over the Soret, visible near-infrared regions spectrum. Electron paramagnetic resonance measurements also made between 10–30 K. MCD unbound enzyme possesses a bi-signate band 1000 nm, similar those seen other high-spin haemoproteins. On addition this is replaced by positive 1500 which assigned low-spin haem. This switch in spin state was observed EPR signals g 7.09 5.17 titrating away 2.58, 2.33 1.81. Significant changes were apparent even ratios /haem less than one. Integrations spectra bave check spectrum extinction coefficients, measured Soret bands evidence found for more one binding process. cyanide-bound from 350 700 nm strongly suggests that haem closely related ring chlorin type.