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HPLC and HPLC-MS analysis of urinary N(epsilon)-monomethyl-lysine
1Department of Pharmacology and Pharmacotherapy, Semmelweis University, H-1089 Budapest, Nagyvárad tér 4, Hungary.
Abstract:
Administration of (14)C-labelled L-deprenyl to rats results in the urinary elimination of a 14C-labelled compound. The 9-fluorenylmethoxycarbonyl chloride-reacted urine sample is fractionated by high-performance liquid chromatography (HPLC) on an octadecyl silica stationary phase. N(epsilon)-Monomethyl-lysine is identified in the fraction containing the majority of the radioactivity. Structural elucidation is carried out using HPLC-mass spectrometry in atmospheric pressure chemical ionization mode. Identification of the 14C-labelled fragment in Ne-monomethyl-lysine is an experimental proof that an N-methylated amino acid is generated by transmethylation from a well-known drug. This type of transmethylation may have basic importance in the positive side effects of certain drugs.
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