Comparison of whole blood, plasma and nails as monitors for the dietary intake of selenium

Haem peroxidases are globular proteins with an iron-porphyrin complex as prosthetic group. They catalyze the oxidation of substrate by peroxides, frequently via free-radical intermediates. The catalytic cycle involves changes in the redox states of the prosthetic group, that can be monitored by changes in the intense absorption spectra. During the past decades, considerable scientific effort has been put into the elucidation of the mechanisms of reactions catalyzed by these enzymes. Radiation-chemical techniques have made an important contribution by providing information on the redox states of the enzymes and their interconversions, as well as on the properties of the free-radical intermediates involved.