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Updated: Jul 18, 2026

Metabolic Pathway Confirmation and Discovery Through 13C-labeling of Proteinogenic Amino Acids
Published on: January 26, 2012
2-Keto-4-methylthiobutyrate, an intermediate in the methionine salvage pathway, is a good substrate for CtBP1
Younes Achouri1, Gaëtane Noël, Emile Van Schaftingen
1Université catholique de Louvain, Christian de Duve Institute of Cellular Pathology, Avenue Hippocrate 75, B-1200 Brussels, Belgium. younes.achouri@bchm.ucl.ac.be
Abstract:
In the present work, we have studied the kinetic properties of the catalytic domain of CtBP1, a co-repressor belonging to the d-2-hydroxyacid dehydrogenase family and known to reduce pyruvate in the presence of NADH. CtBP1 acted on a variety of alpha-keto acids, for which it displayed biphasic curves with inhibition at elevated concentrations, as observed with other dehydrogenases of the same family. Based on catalytic efficiencies, the best substrate was 2-keto-4-methylthiobutyrate, an intermediate of the methionine salvage pathway. It was about 20-fold better than 2-ketoisocaproate and glyoxylate, and 80-fold better than pyruvate. From these data we conclude that 2-keto-4-methylthiobutyrate may be an important regulator of CtBP activity, possibly linking gene repression to the activity of the methionine salvage and spermine synthesis pathways.
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