<prompt> In hemoglobin, iron is bound toHistidineLeucineIsoleucineValine  <response>: 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. 