Effect of various analogues of D-glutamic acid on the D-glutamate-adding enzyme from Escherichis coli

Twenty-four analogues of D-glutamic acid were tested as substrates or inhibitors of the D-glutamate-adding enzyme from Escherichia coli. The best substrates were, in decreasing order of specific activity, D-erythro-4-methylglutamic acid, D-erythro- methylglutamic acid, DL-homocysteic acid, (±)-trans-1-amino-3-carboxy-cyclopentanecarboxylic acid and (±)-trans-1-amino-3-carboxy-cyclohexanecarboxylic acid. Among the different stereoisomers, only the D-erythro isomers for methylglutamic acids, and the trans isomers for the cyclic analogs, were substrates. Apart from the D-erythro-3 and 4-methylglutamic acids and DL-homocysteic acid, none of the examined compounds significantly inhibited the addition of radioactive D-glutamic acid to UDP-N-acetylmuramyl-L-alanine.