Explain how hemoglobin/myoglobin bind O 2 . What roles do the heme group, Fe2+ , twoconserved his3dine residues and several nearby hydrophobic amino acids play

Hemoglobin and myoglobin are proteins that bind to oxygen and are crucial for life. They are found in the red blood cells and muscle cells respectively. The process of oxygen binding involves several components including the heme group, Fe2+, two conserved histidine residues, and several nearby hydrophobic amino acids.

1. Heme Group: The heme group is a complex molecule that contains an iron atom (Fe2+) at its center. This iron atom is the actual site where oxygen binds. The heme group is embedded within the protein structure of hemoglobin and myoglobin.

2. Fe2+ (Iron): The iron atom in the heme group can form a bond with oxygen. When oxygen is not bound, the iron atom is in a high spin state. When oxygen binds, it causes the iron atom to transition to a low spin state, pulling it into the plane of the heme, which triggers the conformational changes in the protein structure.

3. Histidine Residues: There are two histidine residues that play crucial roles in oxygen binding. The first, called the proximal histidine, is directly bonded to the iron atom. The second, called the distal histidine, is not bonded to the iron but is close to the oxygen binding site. The distal histidine helps stabilize the bound oxygen molecule.

4. Hydrophobic Amino Acids: Several hydrophobic amino acids are located near the heme group. These amino acids help to create a hydrophobic environment that is important for the stability of the heme group and for the conformational changes that occur when oxygen binds.

In summary, oxygen binding to hemoglobin and myoglobin is a complex process that involves the interaction of the heme group, iron, histidine residues, and hydrophobic amino acids. The binding of oxygen triggers conformational changes in these proteins, allowing them to carry out their function of oxygen transport and storage.