Mechanismus der basischen hydrolyse von oligopeptid-4-nitro-aniliden

Oligopeptide-4-nitroanilide alkaline hydrolysis mechanism has been studied in a wide pH-range. In the log k_b vs pH-profile we have identified three different ranges. In the $\text{k}{}_2\text{k}{}_{-1}$ controlled range a stereoelectronic control of the cleavage of the tetrahedral intermediate has been observed m the case, a α-substituent is available for interaction with groups on the tetrahedral carbon atom. In the k₃/k_-1- and in the k₁-range of the hydrolysis no mechanistically differences exist between oligopeptide-4-nitroanilides and acet-4-nitroanilides. Kinetic-D-isotope effects are consistent with the postulated mechanism of hydrolysis.