Tyramine oxidase is the enzyme responsible for the oxidative deamination of tyramine. It was the first enzyme for oxidative deamination that was found to be present in the body. Research for the detection of the enzyme responsible for oxidative deamination began, in 1877, with Oswald  Schmiedeberg’s findings that orally administered benzylamine, a monoamine, to dogs, was deaminated and excreted in the urine as benzoylglycin (hippuric acid). It continued in 1910 by Ewins and Laidlaw’s demonstration that both endogenous monoamines, tyramine, a phenylalkylamine, and tryptamine, and indoleamine, were deaminated and excreted in the urine as p-hydroxyphenylacetic acid and indoleacetic acid, respectively. However, it was only 28 years later, in 1928, that Mary Hare had shown the presence of “tyramine oxidase”, the enzyme responsible for oxidative deamination of the monoamine, tyramine, in the liver. Today, the term “tyramine oxidase” is of history.   In 1937, Blaschko, Richter and Schlossman discovered that tyramine oxidase,  noradrenaline oxidase and aliphatic amine oxidase are the same enzyme, and in 1938, by Zeller’s separation of diamine oxidase from “amine oxidase”, tyramine oxidase became part of the monoamine oxidase enzyme system.

Blaschko H, Richter D, Schlossmann H. The oxidation of adrenaline and other amines. Biochemical Journal 1937; 31: 2187-96

Ewins AJ, Laidlaw PP. The fate of parahydroxyphenylethylamine in the organism. Journal Physiology 1910; 41:78-87.

Hare MLC. Tyramine oxidase I. A new enzyme system in the liver.  Biochemical Journal 1928; 22:968-79.

Schmiedeberg O. Über das Verhaltniss des Ammoniaks und der primären Monoaminbasen zur Harnstoffbildung im Thierkörper. Archiv für experimentelle Pathologie und Pharmakologie 1877; 8:1-14.

Zeller EA. Über den enzymatischen Abbau von Histamin und Diaminen. Helvetica Chimica Acta 1938; 21:881-90

Joseph Knoll

June 5, 2014