hydroxylysine and trimethyllysine

Topics: Aldehydes; Animals; Betaine; Carnitine; Humans; Hydroxylysine; Lysine; Organ Specificity; Rats; Species Specificity

Topics: Amines; Animals; Betaine; Carnitine; Hydroxylysine; Lysine; Rats

Rats injected with N6-[Me-3H]trimethyl-lysine excrete in the urine five radioactively labelled metabolites. Two of these identified metabolites are carnitine and 4-trimethylammoniobutyrate. A third metabolite, identified as 5-trimethylammoniopentanoate, is not an intermediate in the biosynthesis of carnitine; the fourth and major metabolite, N2-acetyl-N6-trimethyl-lysine, is not a precursor of carnitine. The remaining metabolite (3-hydroxy-N6-trimethyl-lysine) is converted into trimethylammoniobutyrate and carnitine by rat liver slices and into trimethylammoniobutyrate by rat kidney slices. In rat liver and kidney-slice experiments, radioactivity from DL-N6-trimethyl-[1-14C]lysine and DL-N6-trimethyl-[2-14C]lysine was incorporated into N2-acetyl-N6-trimethyl-lysine and 3-hydroxy-N6-trimethyl-lysine, but not into trimethylammoniobutyrate or carnitine. A procedure was devised to purify milligram quantities of 3-hydroxy-N6-trimethyl-lysine from the urine of rats injected chronically with N6-trimethyl-lysine (100 mg/kg body wt. per day). The structure of 3-hydroxy-N6-trimethyl-lysine was confirmed chemically and by nuclear-magnetic-resonance spectrometry [Novak, Swift & Hoppel (1980) Biochem. J. 188, 521--527]. The sequence for carnitine biosynthesis in liver is: N6-trimethyl-lysine leads to 3-hydryxy-N6-trimethyl-lysine leads to leads to 4-trimethylammoniobutyrate leads to carnitine.

Topics: Animals; Carbon Radioisotopes; Carnitine; Chemical Phenomena; Chemistry; Chromatography, Thin Layer; Hydroxylysine; Kidney; Liver; Lysine; Models, Biological; Rats; Tritium

(1)H and (13)C nuclear-magnetic-resonance spectroscopy and functional-group analysis were used to determine the molecular structure of an isolated metabolite (II(b)) of trimethyl-lysine as 3-hydroxy-N(6)-trimethyl-lysine, an important intermediate in the conversion of trimethyl-lysine into trimethylammoniobutyrate and carnitine [Hoppel, Cox & Novak (1980) Biochem. J.188, 509-519]. Functional-group analysis revealed the presence of a primary amine and reaction of metabolite (II(b)) with periodate yielded 4-N-trimethylammoniobutyrate as a product, showing 2,3-substitution on the molecule and suggesting that the 3-substitution on the molecule may be an alcohol ([unk]CH-OH), amine ([unk]CH[unk]-NH(2)) or carbonyl ([unk]C=O) functional group. (1)H integration ratios, (1)H and (13)C chemical-shift data and (1)H and (13)C signal multiplicities from the sample (II(b)) were used to complete the identification of metabolite (II(b)) as 3-hydroxy-N(6)-trimethyl-lysine. For example, the proton multiplet at delta 4.2p.p.m. and doublet at delta 4.1p.p.m., positions representative of amine or alcohol substitution on methylene carbon atoms, integration ratios of 1:1:2:9:4 and a positive ninhydrin test suggest 3-hydroxy-N(6)-trimethyl-lysine as the molecular structure for metabolite (II(b)). (13)C chemical-shift data obtained from the sample (II(b)) and compared with several model compounds (trimethylammoniohexanoate, trimethyl-lysine and 3-hydroxylysine) resulted in generation of the spectrum of the metabolite and allowed independent identification of metabolite (II(b)) as 3-hydroxy-N(6)-trimethyl-lysine. The (1)H spectrum of erythro- and threo-3-hydroxylysine are presented for comparison, and the (1)H and (13)C n.m.r. spectra of the erythro-isomer support this analysis.

Topics: Carbon Radioisotopes; Hydroxylysine; Lysine; Magnetic Resonance Spectroscopy; Molecular Conformation; Tritium