Scheme 1. A potential reaction mechanism of canavanine-γ-lyase: starting with free canavanine, PLP-canavanine aldimine (1) formation, quinonoid (2) formation, canavanine ketimine (3) formation, elimination of hydroxyguanidine resulting in vinylglycine ketimine (4), water addition yielding homoserine ketimine (5), homoserine aldimine (6) formation, and release of homoserine by reformation of PLP-imine with the internal lysine. Wavelengths indicate UV-Vis maxima in UV-Vis data shown in Fig. S8 (ESI†) next to reaction intermediates that could potentially cause the observed absorption.
