Amino Acids and Mutations

The Twenty Common Amino Acids Found in Proteins

The R group of each amino acid is circled in green. The R group contributes the unique properties of each of the different amino acids. A protein's three dimensional shape is a result of the interactions between the R groups of amino acids in different parts of the chain. These interactions include ionic bonds, hydrogen bonds, disulfide bonds, and hydrophobic interactions.

One amino acid substitution in a hemoglobin protein causes Sickle Cell Anemia
The function of normal human red blood cells, which are disk-shaped, is to transport oxygen from the lungs to the other organs of the body. Each red blood cell contains millions of molecules of hemoglobin that carries the oxygen. A slight change in the order of the amino acids in the hemoglobin molecule (valine substituted for glutamine), which has only 146 amino acids, causes sickle-cell disease. Abnormal hemoglobin molecules stick together and crystallize deforming the red blood cells. The deformed blood cells then clog tiny blood vessels impeding the flow of blood. Sickle-cell anemia kills about 100,000 people per year in the US.
Normal hemoglobin (eight out of the 146 amino acid units of normal hemoglobin)
Val	His	Leu	Thr	Pro	Glu	Glu	Lys
Sickle-cell hemoglobin (the same section as above as found in Sickle-cell hemoglobin)
Val	His	Leu	Thr	Pro	Val	Glu	Lys
Good red blood cells						Sickle cell blood cells pictures from: www.cc.nih.gov/ccc/ ccnews/nov99/