One Of Life's Great Proteins V Hemoglobin
Hemoglobin is a protein, which is one of the four basic biological molecules of life. Proteins have many functions and are versatile molecules. They are important for building and repairing cells and tissues and also as enzymes that are used in catabolic processes within an organism. Hemoglobin is the main substance of the red blood cell and it helps red blood cells carry oxygen from the air in our lungs to all the parts of our body. The other three molecules of life are carbohydrates, lipids, and nucleic acids. Proteins can also be called polypeptide chains because they are made up of subunits, amino acids that are linked with peptide bonds. Since hemoglobin has such an importance to the function in our bodies it has an importance in our society as well. In order to understand how and why hemoglobin is essential one must understand the chemistry behind this molecule.
There are thousands of different polypeptides due to the variety of amino acid arrangements in forming chains. Amino acids are organic compounds that have an amino group, a hydrogen atom, and a carboxyl group attached to an asymmetric carbon (a carbon that has four different groups attached to it with covalent bonds). In all amino acids these three groups are always present. It is the fourth group that always differs and makes all of the different amino acid structures. This group is known as the R group because it changes for every amino acid. There are 20 basic amino acids that are found in proteins the simplest being glycine (R group = H). See Figure 1 for a view of the amino acid structure. The number and arrangement of these amino acids is what determines different polypeptides. The carboxyl group of one amino acid bonds with the amino group of another amino acid to form a polypeptide with a peptide bond.
Every amino acid can be classified as either polar or non-polar and consequently hydrophobic or hydro...