Oxyhemoglobin absorption spectra

Fig. 2. Absorption spectra of compounds formed upon addition of nitrite to oxyhemoglobin (Watts and Faulkner, 1953). Ferricyanide and the lower concentration of nitrite produce the typical absorption spectrum of methemoglobin. The curve obtained with the higher concentration of nitrite probably represents a mixture of...

Fia. 5. Changes in the absorption spectrum of oxyhemoglobin brought about by ascorbic acid (Riedesel and Watts, 1952). All solutions except the original oxyhemoglobin were stored for 3 hours at 46° C. (113° F.) before reading. 

B. Oxyhemoglobin plus 0.02% nitrite. This is the typical absorption spectrum of methemoglobin. Solution is brown in color. 

D. Oxyhemoglobin plus 0.02% nitrite and 0.1% ascorbic acid. Typical absorption spectrum of nitric oxide hemoglobin. Bright red. 

The absorption spectrum of oxyhemoglobin is markedly different from that of hemoglobin. The former has two sharp well-defined absorption bands between D and E, while the latter has only one. Such differences in the absorption spectra cannot be explained on the grounds of a difference in state, nor in the degree of dispersion of the hemoglobin. Rather it indicates a change in the chemical composition of the two substances. 

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