The Structure and Properties of Globular Proteins

Stereodrawing of the molecule of Glycera hemoglobin. The positions of the alpha carbon atoms are shown, connected by straight rods. The heme group is also shown. [From E. A. Padlan and W. E. Love, Journal of Biological Chemistry 249, 4067 (1974).] 

The two kinds of chains are rather similar about half of the residues are the same in corresponding loci (note deletion of His between loci 1 and 2 in the alpha chain). Some invertebrate hemoglobins consist of molecules with only one kind of chain. 

The experimental values agree well with this expression. 

One possibility is that the heme-heme interactions are so strong that there are no intermediates in appreciable concentration between Hb and 

Another simple assumption is that the hemes interact very strongly with one another in pairs, with no interaction between the pairs. The corresponding equilibrium expression 

---