The fate of alpha and epsilon lysine amino groups in rat liver in vitro (author's transl)

The fate of alpha and epsilon lysine amino groups has been explored in rat liver homogenate by means of L-lysine labelled selectively in the two positions. alpha-15NH2 and epsilon-15NH2 are rapidly incorporated into the amino group of glutamic acid and it seems at first that both transaminations occur simultaneously. But the reversible transfer of the amino group between alpha-aminoadipic acid and glutamic acid, determined by means of labelled alpha-aminoadipic acid, proceeds swiftly, and the incorporation of alpha-15NH2 from the corresponding labelled lysine in glutamic acid may be easily explained by epsilon-transamination and saccharopine formation. The direct transamination of the alpha-amino group of L-lysine is most improbable and might be limited to some microorganisms and to epsilon-N-substituted lysine derivatives.