Studies on the structure of hemoglobin: III. Physiochemical properties of reconstituted hemoglobins

Abstract Artificial hemoglobins have been reconstituted from native human globin and the following hemes: mesoheme, deuterheme, chloroheme (or Spriographis heme) and hematoheme. All these differ from protoheme in the side chains of the porphyrin ring at position 2 and 4. Some physical and physiochemical properties of thse hemoglobins have been determined. The spectral properties were similar to those of protohemoglobin. The sedimentation coefficients of all these hemoglobins had values near to 4.0 S. The stability to heat and alkali denaturation decreased in the order: proto-, meso-, deutero-, and hematohemoglobin. The O 2 equilibrium of these unnatural hemoglobins also differed from that of protohemoglobin, being characterized by a decrease of the heme-heme interactions. The results have been correlated with the decrease in affinity of the various modified hemes for globin and suggest that the vinyl groups of the heme play an important role in determining the conformation of the hemoglobin molecule.