Covalent bond formation between amino acids and lignin: Cross-coupling between proteins and lignin.

Highlights: [•] The reaction of aromatic amino acids with intermediates of lignin biosynthesis was examined. [•] Products formed from reaction of amino acids with intermediates of lignin biosynthesis were identified by mass spectroscopy. [•] Amino acid adducts were formed with Tyr, Thr and Cys through a reaction of the side-chain with the quinone methide. [•] The cross-coupling was also shown to occur at the protein level. [•] These results show how peptide linkages can be introduced into the lignin polymer. [Copyright &y& Elsevier]