(3R) and (3S) 3-deoxy-3-fluoro-7-phospho-D-arabino hept-2-ulosonic acids (3R and 3S-3F-DAHP) the 3-fluoro analogues of DAHP were synthesized from the corresponding 2-deoxy-2-fluoro hexose-6-phosphates. 3R- and 3S-3F-DAHP were tested as substrates for 3-dehydroquinate synthetase from E. coli. Determination of kinetic parameters showed that their apparent Km and Vm were in the same order of magnitude for these two compounds. Further conversion of 3R- and 3S-3F-DAHP into (6R) and (6S) 6-fluoro dehydroshikimate and (6R) and (6S) 6-fluoro shikimate, respectively, was investigated and results are discussed.

Chemical Phenomena↗

PubMedDate not supplied

Conformational study in water by NMR and molecular modeling of cyclic glutamic acid analogues as probes of vitamin K dependent carboxylase.

The conformational analysis of four glutamic acid analogues containing a cyclopentyl or cyclohexyl ring, substituted in position 1 by a BOC protected amino group and a methyl ester group and in position 3 by a free carboxylate group, has been carried out in an aqueous environment, by 1H and 13C NMR spectroscopy, and molecular dynamics (MD). Their structural properties were under investigation for a structure-activity relationship analysis to determine the preferred conformation in the carboxylase active site. For each compounds, resulting conformations from NMR and MD data were analyzed and classified according to the dihedral angles chi 1 and chi 2, the distances and the spatial distribution involving charged or substituted C- and N-terminal groups. A reduced number of conformational families were found to be in qualitative agreement with NMR and MD data. A comparison between these different classes of the active and nonactive derivatives was achieved.

Animals↗

PubMedDate not supplied

An enzymatic synthesis of 4-methyl-L-glutamic acid diastereoisomers.

(2S,4R)-"erythro"- and (2S,4S)-"threo"-4-methylglutamic acids have been prepared by glutamate dehydrogenase-catalyzed reductive amination of 2-keto-(R,S)-4-methylglutaric acid, in the presence of NH4+ ions, NAD+, and a NADH recycling system (ethanol-alcohol dehydrogenase), followed by separation by anion-exchange chromatography. Nuclear magnetic resonance, electrophoretic, chromatographic, and optical properties of both isomers are reported, together with the conditions leading to the four-carbon epimerization.

Animals↗