The occurrence of εN-methyllysine in human urine

1. 1. An unknown ninhydrin-positive compound was detected in human urine when the basic fraction was analysed by ion exchange chromatography and by two-dimensional paper chromatography. The unknown metabolite and ε- N-methyllysine showed similar properties when examined by these techniques. 2. 2. Fractions from the ion exchange column were analysed by high-voltage electrophoresis and by paper chromatography in three solvent systems. The metabolite was identified as ε- N-methyllysine. 3. 3. The mean level in urine from five normal subjects was 39.4μmoles/24h, when estimations were made on hydrolysed urine. Values on unhydrolysed urine were somewhat lower. 4. 4. The excretion of ε- N-methyllysine did not diminish appreciably after starvation suggesting that the metabolite is mainly of endogenous origin. 5. 5. It is postulated that urinary ε- N-methyllysine originates from breakdown of histories.