Oxidation of putrescine and cadaverine derivatives by diamine oxidases

A range of putrescine and cadaverine derivatives has been synthesized and assayed as substrates for the diamine oxidases from pea seedlings and pig kidney. KM and Vmax data are reported, mainly for the pea enzyme. N-Alkylputrescines and C-alkylcadaverines are generally poorer substrates than the parent compounds with up to 4500-fold reduction in Vmax. There is significantly less variation in KM values, indicating that the binding site of the pea enzyme is relatively non-specific and that enzymic specificity lies at the catalytic stage. This suggests that poor substrates might act as convenient, short-lived inhibitors of diamine oxidases.