Propionate, a source of β-alanine, is an inhibitor of β-alanine methylation in Limonium latifolium, Plumbaginaceae

The origin of beta-alanine was investigated in Limonium latifolium (Plumbaginaceae), an angiosperm species that methylates beta-alanine to beta-alanine betaine, an osmoprotective compound. The hypothesis that propionate metabolism leads to beta-alanine in L. latifolium was tested using radiotracer labeling techniques. 2-[C-14]-Propionate was supplied to leaf and root tissues. Following incubation for defined periods, radiolabel was identified in beta-alanine. However, in both the tissues, little radioactivity was found in the methylated derivatives of beta-alanine namely N-methyl beta-alanine, N,N-dimethyl beta-alanine and beta-alanine betaine, suggesting that propionate was inhibitory to beta-alanine methylation. This conclusion was confirmed by in vitro assays wherein propionate was found to be highly inhibitory to beta-alanine N-methyltransferase activity in a leaf protein fraction.