Spectral analysis of Fe(III)-complex reduction by hemoglobin: possible mechanisms of interaction.

1. Hemoglobin is capable of electron transfer to Fe(III)-complexes of ATP, EDTA, NTA, and citrate leading to formation of reduced Fe(II) and its concurrent release from these chelating compounds as evident in the formation of a Fe(II)-Tris 2,2' bipyridine complex. 2. Multi-component analysis of kinetic spectra in the visible region (700-500 nm) has permitted a determination of the effect of various chelating molecules bound to Fe(III), pH, the effects of ionic strength, temperature, and the molecular nature of the Fe(III)-complex on reaction rates. 3. We have examined and compared the reactivities of normal adult hemoglobin A (alpha 2 beta 2) to reduce these Fe(III)-complexes and suggest possible mechanism(s) for the electron transfer process.