The Oxidative Demethylation of Sarcosine to Glycine

The coupled feeding of sarcosine (N-methylglycine) and benzoic acid, like the coupled feeding of glycine and benzoic acid, results in the excretion of hippuric acid at a rate greater than that when benzoic acid is fed alone (1). When sarcosine containing an excess of N16 is fed to rats, the isotope content of the amino acids of the tissues is almost identical with that of animals fed glycine containing N16. The isotope concentration in the glycine from the tissue proteins is high, while that of the other amino acids is much lower (2). These findings have indicated that sarcosine can be converted to glycine by direct demethylation without deamination. In the present work it has been shown that broken cell preparations of the livers of several species, as well as surviving liver slices, can perform this conversion. The demethylation is an oxidative process in which 1 mole of sarcosine reacts with 1 atom of oxygen with the production of 1 mole of glycine and 1 mole of formaldehyde. The mechanism is shown in the accompanying formula.