The Chemical Mechanism of The Oxidative Deamination of Amino Acids by Catechol and PolYPHENOLASE

Abstract

The continuous deamination of certain amino acids by the system catechol-polyphenolase takes place through intensely colored intermediate compounds. These intermediates are formed by the combination of equimolecular proportions of o-quinone with amino acids or secondary amines. They are presented as structural homologs of adrenochrome or halla-chrome and probably of Szent-Gyorgyi''s tyrin (1925). It is suggested that the continuous deamination is brought about through condensation of the color compound with one further molecule of a suitable amino acid and rearrangement and hydrolysis into keto acid and substituted amino phenol. It is supposed that the latter is re-oxidized with liberation of ammonia and regeneration of the o-quinonoid color compound. A formulation of the chemical mechanism is tentatively proposed and individual steps of the reaction are compared with observations made in the oxidation of amino acids by other polyketo compounds like alloxan and isatin. The conditions and limitations of the reaction are discussed.