In hemoglobin, iron is bound to
The iron atom of hemoglobin has six coordinated bonds : (i) Four bonds are formed between the iron and nitrogen atoms of porphyrin ring system; (ii) Fifth bond is formed between the nitrogen of histidine (proximal histidine: HisF8) of globin; and (iii) Sixth bond is formed with oxygen.
Histidine
Leucine
Isoleucine
Valine