ABSTRACT
Amino acids are organic compounds that contain the basic amine group, NH2, and the acid carboxyl group, COOH. The general formula for amino acids is
For most amino acids the R represents a complex organic group; in glycine, the R represents H (hydrogen). Amino acids are usually known by their common rather than chemical names. For instance glycine, with the structural formula H2N-CH2-COOH, is known chemically as amino acetic acid. For a discussion of the structure of amino acids, consult Harborne (1984) and Bhushan and Martens (1996). In living aqueous systems, amino acids exist predominantly as dipolar ions referred to as “zwitterions” and represented by the formula
Because of the ionic charge, separation of amino acids from inorganic salts may be difficult (Scott, 1969) and requires considerable sample cleanup as described in Chapter 4. Amino acids are soluble in water, but some are less soluble than others. Alcoholic 0.5 M HCl should be used to prepare solutions of amino acids that are only sparingly soluble in water.
