Abstract
A native globin from the dimeric hemoglobin, hemoglobin I, of the mollusc Scapharca inaequivalvis has been obtained with the acid-acetone method. The globin has a lower sedimentation coefficient than the native protein at neutral pH; its reconstitution product with natural heme has the same physicochemical and functional properties as the native protein, proto- and meso-cobalt hemoglobin I have been prepared and characterized, proto-Cobalt hemoglobin I binds oxygen reversibly with a lower affinity and a lower cooperativity than native hemoglobin I; thus, the changes in the functional properties brought about by substitution of iron with cobalt are similar to those observed in human hemoglobin A. The EPR spectra of deoxy-proto-cobalt hemoglobin I and of the photolysis product of oxy-meso-cobalt hemoglobin I indicate that two histidine residues are the apical heme ligands. The broad signal at g = 2.38 in deoxy-proto-cobalt hemoglobin I points to a constrained structure of the heme site in this derivative which results from a distorted coordination of the hindered proximal histidine. A similar structure has been proposed previously for the α chains in deoxy-cobalt hemoglobin A.
Original language | English |
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Pages (from-to) | 215-220 |
Number of pages | 6 |
Journal | Biochimica et Biophysica Acta (BBA)/Protein Structure and Molecular |
Volume | 704 |
Issue number | 2 |
DOIs | |
Publication status | Published - 1982 Jun 4 |
Externally published | Yes |
Keywords
- (Scapharca)
- Fe-porphyrin
- Hemoglobin
- Metalloprotein
- Reconstituted dimer
ASJC Scopus subject areas
- Structural Biology
- Biophysics
- Biochemistry
- Molecular Biology