The metabolism of lysine

Abstract

The ingestion of large amts. of [iota]-( +) -lysine hydrochloride by the rat produced a greatly increased excretion of urea (or of NH3 if the HCl was not neutralized with NaHC03). Hence, apparently both N atoms were ultimately converted into urea. [iota]-( [long dash] )-Lysine was excreted largely unchanged. A method for measuring the formation or disappearance of lysine in tissue slices with a specific bacterial decarboxylase showed that the kidney demethylates [epsilon]-methyl-lysine to lysine. d-Amino acid oxidase oxidizes [epsilon]-acetyl- and [epsilon]-benzoyl-d-lysine, but is inactive towards lysine. Ornithine oxidized slightly more rapidly than its [delta]-acetyl derivative. [iota]-Amino acid oxidase attacks [epsilon]-acetyl-[iota]-lysine slowly but does not affect [iota]-lysine. The probable intermediate steps in the metabolism of lysine are discussed.