All proteins are polymers of amino acids, which are bifunctional organic compounds that contain both an amino group and a carboxylate group. Differences in the R groups of amino acids cause differences in the properties of amino acids and proteins. The presence of both amino groups and carboxyl groups in amino acids makes it possible for amino acids to exist in several ionic forms, including the form of a zwitterion. The zwitterion is a dipolar form in which the net charge on the ion is zero. Reaction of Amino Acids.
Amino acids can undergo reactions characteristic of any functional group in the molecule.
More than 200 peptides have been shown to be essential to the proper functioning of the human body. Hormones and enkephalins are among the peptides for which functions have been identified. Characteristics of Proteins. Proteins are large polymers of amino acids. Acidic and basic properties of proteins are determined by the acidic or basic character of the R groups of the amino acids comprising the protein.