Reconstitution in vitro of the components and conditions required for the oxidative cross‐linking of extracellular proteins in French bean (Phaseolus vulgaris L.)

Oxidative cross linking of three (hydroxy)proline-rich cell wall proteins, known to be immobilised during the elicitor-induced oxidative burst in French bean cells, was modelled using peroxidases with cysteine or H2O2. Further reconstitution of the homologous system was achieved with a 46 kDa bean cell-wall peroxidase using conditions known to appertain in cell walls prior to the immobilisation. Thus, cell wall alkalinisation and secretion of a reductant have been reconstituted by addition of apoplastic fluid to the wall proteins and the 46 kDa peroxidase with resultant cross-linking. This is the first demonstration of the oxidative cross-linking of cell wall glycoproteins without the addition of external H2O2.