Partners and International Organizations
(English)
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A, B, CZ, DK, FIN, F, D, GR, H, IRL, I, IL, MT, NL, N, PL, P, E, S, CH, GB
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Abstract
(English)
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Glutamate mutase is a coenzyme B12 dependent enzyme that catalyses the conversion of (S)-glutamate to (2S,3S)-3-methylaspartate, a reaction which represents the first step in the fermentation of glutamate to acetate and butyrate in many clostridia. The active site of the enzyme contains three arginine residues that interact with the carboxylate groups of the substrate. The rearrangement has no precedent in organic chemistry therefore making the development of models relevant. New receptors for dicarboxylates containing three guanidinium groups were prepared. The new compounds mimic the espace arrangement of arginine groups in the active site of the B12-dependent enzyme. Binding studies were carried out with the new receptors in order investigate the binding abilities of the model substrate-active site mimic. Isothermal titration calorimetry was used to determine the stoichiometry and the association constant of the trisguanidinium receptors to dicarboxylates (L-glutamate, glutarate, trans-glutaconate) and citrate. The model compounds are able to bind two molecules of dicarboxylates. The strength of binding depends on the relative orientation of the guanidinium groups.
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