Synthesis and in vitro enzyme activity of an oxa analogue of azi-DAP

The synthesis of a novel epoxide inhibitor 6 of meso-DAP epimerase was achieved. A new and convenient assay for meso-DAP epimerase was devised which is a considerable improvement on previously reported assay methods. This assay was used to determine the inhibitory properties of 6. The epoxide 6 shows limited competitive inhibition vs. meso-DAP epimerase, but clear time dependent inhibition indicative of the expected covalent attachment at the active site. Epoxide 6, although an effective inhibitor of meso-DAP epimerase, was unstable at pH 7.3 in aqueous buffer, being hydrolysed to the corresponding diol.