iron containing proteins

Last reviewed 01/2018

• haemoglobin
  • most of the iron in the body is present in the erythrocytes as haemoglobin, a molecule composed of four units, each containing one heme group and one protein chain
  • structure of haemoglobin allows it to be fully loaded with oxygen in the lungs and partially unloaded in the tissues (e.g., in the muscles)
    
    
• myoglobin
  • the iron-containing oxygen storage protein in the muscles, myoglobin, is similar in structure to haemoglobin but has only one heme unit and one globin chain
    
    
• cytochromes
  • several iron-containing enzymes, the cytochromes, also have one heme group and one globin protein chain. These enzymes act as electron carriers within the cell and their structures do not permit reversible loading and unloading of oxygen
  • their role in the oxidative metabolism is to transfer energy within the cell and specifically in the mitochondria
  • other key functions for the iron-containing enzymes (e.g., cytochrome P450) include the synthesis of steroid hormones and bile acids; detoxification of foreign substances in the liver; and signal controlling in some neurotransmitters, such as the dopamine and serotonin systems in the brain
    
    
• ferritin and haemosiderin
  • iron is reversibly stored within the liver as ferritin and hemosiderin whereas it is transported between different compartments in the body by the protein transferrin
    • haemosiderin is the body's insoluble iron store
      
      
• lactoferrin
  • bacteriostatic properties
  • found in various sources including milk, secretions, neutrophils