the heme methyl contact shift pattern has 1-methyl and 5-methyl shifts furthest downfield in both chains and the individual subunits of the intact hemoglobin in both the cyanide- and azide-ligated species , which is consistent with a dominant rhombic perturbation due to the proximal his-f8 imidazole pi bonding in the known structure for human adult hemoglobin .
C2350441
subunits
C0019046
hemoglobin