CROSS-LINKING OF A SYNTHETIC PARTIAL-LENGTH (1-28) PEPTIDE OF THE ALZHEIMER BETA A4 AMYLOID PROTEIN BY TRANSGLUTAMINASE/

Cerebral deposits of beta/A4 amyloid protein is a pathologic sign of A lzheimer's disease. A synthetic partial-length (1-28) peptide of this protein contains one glutamine and two lysine residues. Here we show t hat this peptide can be a substrate of transglutaminase, which catalyz es cross-linking between glutamine and lysine residues in peptides, by demonstrating the formation of multimeric peptides due to the action of this enzyme. A modified (Lys28 to L-norleucine) version of the synt hetic peptide was also cross-linked, but another modified version (Lys 16 to L-norleucine) was very poorly cross-linked, indicating that Lys1 6 is involved exclusively in the cross-linking of the partial-length p eptide catalyzed by transglutaminase.