Introduction-Proteins are a diverse group of substances built from smaller building blocks called amino acids. There are many types of proteins and many functions. Proteins are used for connective tissues providing structural integrity and strength. Proteins are used in the manufacture of genetic materials, hormone production, and cell organelles. Proteins are used for the production of immunoglobulins (antibodies), which protect us from pathogens which might otherwise harm us. There are thousands of uses for the amino acids derived from the protein we obtain in our diet. There are also thousands of protein products manufactured by the body from dietary protein.
To understand why the possibility of nearly an infinite number of proteins exists, let鈥檚 briefly view the chart below illustrating the 20 amino acids that are used by humans.
The 20 biologically active amino acids. There are more amino acids in nature. However, humans utilize only these 20. Amino acids can be bonded together forming a chain. This chain is referred to as a polypeptide (Greek. poly, many: peptide, the bond between the amino acids).
We can take any single amino acid and combine it with a different one, or even the same amino acid. If this process of addition is repeated, we now have a chain of amino acids. This chain is known as a protein, or polypeptide. When viewing the above chart, it鈥檚 not so important at this stage to learn their stuctures, but rather the almost infinite number of possibilities that these amino acids can be mixed and combined to make new proteins. Remember, that changing a single amino acid in the protein chain, completely changes the protein. In medicine, we can see this catastrophic event occuring by single amino acid substitution, by discussing sickle cell anaemia.