We isolated isodityrosine, a diphenyl ether linked amino acid, from cell wall hydrolysates
and from two tryptic peptides of extensin. Determination of the molecular weights, net
charges and composition of the peptides indicated that isodityrosine (IDT) can form a short
intramolecular linkage in sequences consisting of:

Crude extensin precursors were isolated by salt-elution of intact tomato (Lycopersicon
eswlentum) cells cultured on MET medium at 27℃ for 8 d. Monomeric (oligomer-free
monomer, OFM) and oligomeric (monomer-free oligomer, MFO) extensin were separated on
a Bio-Rex 70 (100~ 200 mesh) column (90× 1.5 cm) and purified further by Superose-6 fast
protein liquid chromatography (FPLC). Extensin oligomers crosslinked (EOC) in vitro by a
crude extensin peroxidase were also purified via FPLC. IDT and tyrosine contents of …