Proteins Proteins are the most complex of the three basic nutrients. They consist of very large molecules consisting of carbon, hydrogen, oxygen, and nitrogen. The nitrogen atoms are contained in structures called amino groups. An amino group connected to a carboxylic acid is called an amino acid. Proteins consist of long chains of amino acids, folded back onto themselves in a deliberate manner and held in position with hydrogen bonds.
Protein molecules are sensitive to heat.
When heated to temperatures above about 180 deg. F, they become denatured . A denatured protein is one in which the hydrogen bonds have been broken, causing the protein to coagulate. A good example of a denatured protein is an egg white that has been cooked. The amino acids are still present in a denatured protein, so cooking proteins does not reduce their nutritional value.