The Glutamate Isomerase Reaction: Studies on the Incorporation of Solvent Hydrogen

Abstract

The source of the hydrogen atom that is transferred between the BETA - carbon of glutamate and the methyl carbon of BETA -methylaspartate in the giutamate isomerase reaction was studied by carrying out the coupled isomerase and BETA -methylaspartase reactions in the presence of tritium- or deuterium- labeled water. In the decomposition of glutamate only about 0.1 atom of hydrogen from the solvent was incorporated per mole of mesaconate formed, and this small amount can be attributed to side reactions. In the synthesis of BETA - methylaspartate from mesaconate and ammonia, approximately 1 mole of solvent hydrogen is incorporated, whereas in the conversion of BETA -methylaspartate to glutamate no more hydrogen is taken up. The results indicate that a free proton is not involved in the glutamate isomerase reaction. (auth)