Abstract
Synthesis of γ-glutamyl-L-3, 4-dihydroxyphenylalanine from a γ-glutamyl donor (glutathione or glutamine) and DOPA (L-3, 4-dihydroxyphenylalanine) was examined making use of the partially purified γ-glutamyltranspeptidase from a bacterium, Proteus mirabilis. The optimum pH for γ-glutamyl-DOPA synthesis from glutathione was 9.5 to 11 and the amount of peptide produced increased with the glutathione concentration. The best conditions for γ-glutamyl-DOPA synthesis were investigated and 13mg/ml of γ-glutamyl-DOPA was synthesized with a yield of 6.7% of the substrate, glutathione. The product was isolated from a large scale reaction mixture and the structure determined by physicochemical analyses; PMR spectrometry, mass spectrometry and IR spectrometry. γ-Glutamyl-DOPA synthesis was also performed with glutamine as the γ-glutamyl donor.
