As a Transport Protein

Proteins are compounds that are beneficial to humans, one of which is for the transport process in which a protein that plays a role is twofold, namely hemoglobin and myoglobin in which plays the same but different placements in the blood of the one in the muscle cells but their functions the same as the binding of oxygen and circulate or in transport
Hemoglobin is metaloprotein (iron-containing protein) in red blood cells that serves as a carrier of oxygen from the lungs throughout the body, in mammals and other animals. Hemoglobin is also the bearer of carbon dioxide back to the lungs to the body exhaled. Hemoglobin molecule consists of globin, Apoprotein, and four heme groups, an organic molecule with an iron atom. Mutations in these genes lead to a class of proteins hemoglobin decreased disease called hemoglobinopathy, among which the most common is sickle cell anemia and thalassemia,
Myoglobin is a monomeric protein tertiary function is to keep a back up oxygen in skeletal muscle cells (striated muscle). Protein is made up of approximately 154 amino acid sequence and contains a single heme group (porphyrin chains containing one iron atom). Gena which encodes the protein myoglobin consists of three exons. Myoglobin protein is composed of eight alpha chain named after the Latin alphabet (A through H). Myoglobin structure was first determined in 1958 by John Kendrew and his friends, so in 1962 he received the Nobel Prize in chemistry.
Unlike hemoglobin which has four heme groups, myoglobin has only a single heme group that binds oxygen intracellular function. Cluster heme is bound by a histidine side chain, ie the chain near the histidine (proximal) that bind heme directly in the chain of hydrophobic proteins and histidine far (distal), which serves to stabilize the heme is bound oxygen.