Abstract:
Animals exposed to foreign organic compounds have developed "detoxication mechanisms" to eliminate such compounds from their bodies. These mechanisms seem to be isolated from normal metabolic functions in the animals concerned and maybe special biochemical defence mechanisms. Aromatic carboxylic acids are an example of these foreign compounds. They are unique in being practically the only compounds excreted by animal bodies with amino acids, although they may also be detoxified as glycosides. This occurs most frequently with glycine, although a variety of amino acids are used including ornithine, glutamine, glutamic acid, arginine, aspartic acid, serine and taurine. (Williams 1963, Smith 1969).
One amino acid is usually used predominantly when whole animal experiments are performed using relatively large doses of the foreign compound (e.g. 500 mg/kg benzoic acid). This particular peptide is often characteristic of a taxonomic group and has been used as the basis of comparative studies. (Smith 1964). Glycine, although used widely has little taxonomic value as this mechanism is found in most vertebrates, most insects and some crustaceans. (Smith 1964). However ornithine is confined to a few families of birds and reptiles (Baldwin, Robinson and Williams 1960, Smith 1958). In the one animal a variety of amino acids may be detected in the conjugates formed especially where low doses are used or detection techniques can pick up small amounts of conjugates. (Hitchcock and Smith 1966, Essac and Cassida 1968).
