Synthesis and characterization of a series of novel glutamic gamma-N-15-anilide dipeptides

The preparation of a series of novel Cbz-Gln-Gly dipeptide derivatives is r eported, wherein the gamma-carboxamide groups of the glutamine side chains have been modified to gamma-N-15-anilides which are substituted in the para position with -NO2, -Cl, -H, -CH3, -OCH3, and -N(CH3)(2). Characterization of the free anilines (pK(a) values and N-15 NMR chemical shifts) and corre sponding gamma-anilides (N-15 NMR chemical shifts and FTIR wavenumbers) is also reported. Correlation of these physicochemical data to Hammett substit uent parameters (sigma(para)) is discussed. These novel dipeptide derivativ es should prove to be generally useful for structure-function enzymology st udies of gamma-glutamyl transferring enzymes.