mofegiline and aminoacetone

Increase in methylglyoxal is thought to be involved in different pathological conditions. Deamination of aminoacetone by semicarbazide-sensitive amine oxidase (SSAO) leads to production of methylglyoxal. We have synthesized aminoacetone and developed a novel HPLC procedure for its quantitative determination. The urinary excretion of aminoacetone is approximately 20-30 microg/mouse/day, and the concentration is about 0.5 microg/g in mouse liver and small intestine. SSAO inhibitor increases aminoacetone levels in both tissues and urines. Results confirm that aminoacetone is an endogenous substrate for SSAO. However, data also indicate that deamination is not the only catabolic pathway for aminoacetone.

Topics: Acetone; Allyl Compounds; Amine Oxidase (Copper-Containing); Amino Acids; Animals; Anion Exchange Resins; Butylamines; Chromatography, High Pressure Liquid; Chromatography, Ion Exchange; Enzyme Inhibitors; Fluorenes; Intestinal Mucosa; Intestines; Liver; Male; Mice; Pyruvaldehyde; Rats; Rats, Wistar; Reproducibility of Results

Methylglyoxal, a toxic aldehyde, has been reported to be increased in diabetes and has been claimed to be related to diabetic complications. Aminoacetone, an intermediate in the metabolism of threonine and glycine, has been proposed to be an endogenous substrate for semicarbazide-sensitive amine oxidase (SSAO). Methylglyoxal is the product. An HPLC procedure for the determination of SSAO activity toward aminoacetone in vitro is described. It was observed in previous assays that methylglyoxal formed via deamination of aminoacetone was quite unstable and led to erroneous results. o-Phenylenediamine (o-PD) was therefore employed for derivatization of methylglyoxal. o-PD does not affect SSAO activity and can be included in the enzyme reaction mixture for continuous trapping of methylglyoxal. This can avoid the loss of methylglyoxal during incubation. Deamination of aminoacetone by human umbilical artery SSAO was confirmed with this improved assay. The values of Km and Vmax, are 125.9 +/- 20.5 microM and 332.2 +/- 11.7 nmol/h/mg protein, respectively. Deamination of aminoacetone was nearly completely inhibited by 1 mM semicarbazide and 1 microM MDL-72974A, a potent selective SSAO inhibitor, whereas MAO inhibitors clorgyline (1 mM) and deprenyl (1 mM) had no inhibitory effect.

Topics: Acetone; Allyl Compounds; Amine Oxidase (Copper-Containing); Benzylamines; Butylamines; Catalysis; Chromatography, High Pressure Liquid; Clorgyline; Deamination; Enzyme Inhibitors; Humans; Kinetics; Monoamine Oxidase Inhibitors; Phenylenediamines; Pyruvaldehyde; Selegiline; Semicarbazides; Umbilical Arteries