PEPTIDE-SYNTHESIS AT HIGH-PRESSURE - ACTIVATION VOLUME OF A PEPTIDE COUPLING, SYNTHESIS OF A GLUTATHIONE DERIVATIVE

From the pressure-induced rate enhancement the activation volume of th e peptide coupling 1 with the sodium salt of glycine 2 leading to the corresponding dipeptide derivative 3 was determined to be strongly neg ative (Delta V-not equal = -(19.3 +/- 0.5) cm(3)mol(-1) at 51.7 degree s C, CH3OH). This finding indicates that an association with the devel oping of charges proceeds in the rate-determining transition state. Th e pressure-induced peptide coupling was exploited to synthesize a deri vative (12a, b) of glutathione (gamma-Glu-Cys-Gly), a biologically imp ortant tripeptide, starting from either glycine or glutamic acid.