CEREAL DIETARY PROTEINS WITH SITES FOR CROSS-LINKING BY TRANSGLUTAMINASE

The ability of several cereal proteins to act as substrates for transglutaminase purified from guinea pig liver was investigated. Among the various dietary proteins tested, wheat glutelins and gliadins, as well as purified A-gliadin, were found to be the most effective acyl donor substrates for transglutaminase. In particular, these proteins seemed to be able to produce not only γ(glutamyl) spermidine adducts but also polymeric complexes, probably through intermolecular ε(γ-glutamyl)lysine crosslinks. In the case of A-gliadin, the single lysyl residue occurring in the amino acid sequence (Lys-186) is supposed to act as acyl acceptor site. The peptic-tryptic fragments of gliadins and prolamines of different origin behaved as transglutaminase substrates similarly to native gliadin, mostly in giving rise to large Mr polymers. These results are consistent with the hypothesis that animal transglutaminase may be involved in the metabolism of cereal dietary proteins, or of their peptide fragments, when present either in the intestinal lumen or in the mucosal cells. © 1990.