A study of the oxidation of 3:4-dihydroxyphenyl-<i>N</i>-methylalanine with reference to its possible function as a precursor of adrenaline

Abstract

THE close structural relationship which adrenaline bears to two amino-acids which are found in proteins suggests that either of them may logically be re- garded as its parent substance. These two amino-acids, phenylalanine and tyrosine, possess almost the same carbon skeleton as adrenaline and might give rise to the latter by successive oxidation, methylation of the nitrogen atom and loss of CO2. Investigators have from time to time unsuccessfully attempted to demonstrate a synthesis of adrenaline in this manner. Hall6 [1906] exposed the adrenal glands freshly removed from the body to solutions of tyrosine and by gravimetric assay claimed to have obtained an augmentation in adrenaline content. Ewins and Laidlaw [1910] repeated and extended the experiments of Halle, applying specific biological methods to the estimation of adrenaline. It was conclusively shown that no stage requisite to the synthesis of adrenaline from tyrosine is brought about under these conditions. The failure to obtain direct evidence of such by the action of surviving adrenal tissue does not mean that the intact organ cannot accomplish this synthesis or that the hypothesis as to the gross chemical mechanism is wrong; neither is there any evidence to suggest that all or even part of these requisite changes need take place within the adrenal gland.