In this work we show that it is possible to prepare and study a cobalt-substituted hemoglobin—a coboglobin (Cb).—and that this reconstituted metalloprotein exhibits reversible oxygen binding. The effect of the protein environment on Co(II)-protoporphyrin IX is directly observed by esr measurements on deoxy- and oxy-Cb and by oxygen uptake measurements, all of which may be compared with similar measurements on the free metalloporphyrin. Reversing our point of view, we compare oxygen binding to Cb with that of hemoglobin, and thus investigate the relationship of the metal atom and metaloxygen binding to such characteristics of the nature proteins as cooperative oxygen uptake.
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