Synthesis and Testing of Heterocyclic Analogs of Diaminopimelic Acid (DAP) as Inhibitors of DAP Dehydrogenase and DAP Epimerase

Abstract

Substrate analogues were synthesized and examined as inhibitors of diaminopimelic acid (DAP) dehydrogenase from Bacillus sphaericus and of DAP epimerase from Escherichia coli. These enzymes produce meso-DAP (3) (a precursor for L-lysine and for peptidoglycan) from L-tetrahydrodipicolinic acid (1) and ll-DAP (2), respectively. The epimerase was purified by an improved procedure and confirmed to require both carboxyl and both amino groups for substrate recognition using deuterium-exchange experiments with DAP isomers, L-lysine, D-lysine, L-a-aminopimelate, and racemic -aminopimelate. An imidazole analogue of DAP, (2S)-2-amino-3-(4-carboxyimidazol-1 -yl)propanoic acid (4), was synthesized by condensation of benzyl imidazole-4-carboxylate (8) with JV-benzyloxycarbonyl(Cbz)-Lserine jS-lactone (9) (product structure confirmed by X-ray analysis) followed by hydrogenolytic deprotection. Two other analogues, (2S,J'/?)-2-amino-3-(3-carboxy-2-isoxazolin-5-yl)propanoic acid (5) and its 5'S diastereomer 6, were prepared by condensation of methyl jV-Cbz-L-allylglycinate (13) with methyl chlorooximidoacetate ( 14) followed by separation of isomers and deprotection with N aOH and MeaSiCl/Nal. Similar condensation of ethyl chlorooximidoacetate with ethylene and of 14 with ethyl acrylate generated isoxazolines, which were saponified to 2-isoxazoline-3-carboxylic acid (25) and 2-isoxazoline-3,5-dicarboxylic acid (26), respectively. None of the compounds show significant inhibition of DAP epimerase or DAP dehydrogenase with the exception of 6, which is a potent and specific inhibitor of DAP dehydrogenase. At pH 7.5 or 7.8, compound 6 shows competitive inhibition (X¡ = 4.2 µ ) with tetrahydrodipicolinic acid (1) for the forward reaction and noncompetive inhibition (X¡ = 23 µ ) with meso-(3) for the reverse process.Preliminary tests for antimicrobial activity demonstrate that 6 inhibits the growth of B. sphaericus, which relies exclusively on DAP dehydrogenase to produce 3.

A convenient and efficient synthesis of (S)-lysine and (S)-arginine homologues via olefin cross-metathesis

“…Reaction of 5 with half an equivalent of the protected allylglycine derivative 6 16 and Grubbs' ruthenium catalyst I in an analogous manner to reported cross-metatheses of allylglycines 17,18 afforded 7 in moderate yield (69%) as a mixture of E/Z stereoisomers. It is interesting to note that a homo-dimer of the protected allylglycine 6 was not observed as sometimes reported for similar cross-metathesis conditions with allylglycine derivatives.…”

Effect of analogues of diaminopimelic acid on the meso‐diaminopimelate‐adding enzyme from Escherichia coli

“…There has been growing interest in the design and synthesis of A2pm analogues, some of which have been assayed either for antibacterial activity (see [3] for a recent example) or for a specific effect on the epimerase [4][5][6][7][8][9], the decarboxylase [9][10][11], the dehydrogenase [5,8,9] or less frequently the A2pm-adding enzyme [12][13][14][15]. Herein we take *Corresponding author.…”

Microbial enantioselective removal of the N-benzyloxycarbonyl amino protecting group

“…Allylglycine enantiomers and their N-protected derivatives have been used as general synthetic intermediates for the access to glutamic acid side chain homologues [18], lysine and arginine homologues [19] or isoxazoline derived amino acids [20]. When Cbz-dl-allylglycine was incubated in preparative conditions with 7C1 lyophilized powder, in optimized conditions, hydrolysis stopped at 50% conversion as expected (see Supplementary Material, Fig.…”