Light absorption and paramagnetic susceptibility of the derivatives of horse and Chironomus methemoglobins and of horse metmyoglobin
Scheler, W.; Schoffa, G.; Jung, F.
Biochemische Zeitschrift 329(3): 232-246
1957
ISSN/ISBN: 0366-0753 PMID: 13522700 Document Number: 3151
Light absorption maxima and extinction coefficients are reported for methemoglobin obtained from horse oxyhemoglobin and the larvae of Chironomus plumosus and metmyoglobin from the musculature of the horse heart. The following derivatives were studied: F , water, formate, acetate, OCN-, SCN-, OH-, NO2-, SeCN-, imidazole, CN-and N3-. All methemoglobin compounds may be arranged in one series on the basis of their light absorption, of which fluoride and cyanide methemoglobin are the extreme spectral types. The Soret band of porphyrin and hemoglobin possesses an oscillation intensity of approximately 1. The paramagnetic susceptibility is reported for all compounds studied. A strict correlation exists between the position of the absorption maximum of the violet band (Soret band) and the susceptibility. A less distinct relationship exists between the position of the green and red bands and the susceptibility. With decreasing susceptibility of a methemoglobin derivative, its maxima are shifted toward longer wave-lengths. The higher the susceptibility of the complex, the more intensive is the red band. The mutual exchange between protein and ferriheme decreases in the following order: hemoglobin, Chironomus hemoglobin, myoglobin. Pauling's hypothesis of a concrete number of free electrons for individual methemoglobin derivatives has been rejected. The varying susceptibilities of methemoglobin compounds is believed due to varying proportions of one completely co-valent and one completely ionic iron complex.
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