Dityrosine crosslinking of 33-mer gliadin oligomers. Towards understanding gliadin related disorders

HERRERA, M.G; AMUNDARAIN., M. J; COSTABEL. M.D; SEWALD. N.; DODERO.V.I

Congreso; Biointeractomics from Bimolecular interactions to networks; 2016

Gliadin is highly immunogenic protein which is not completely digested by humans. After proteolytic degradation, a resistant 33-mer peptide, LQLQPF(PQPQLPY) remains intact, reaching the gut epithelium. This 33-mer gliadin fragment is considered as one of the most important immunological modulator peptides responsible for celiac disease. Although the immunological response observed in the chronic phase of celiac disease is well characterized, the initiation of the inflammatory events is still obscure. Recently, we reported that 33-mer oligomerizes under physiological conditions, forming spherical oligomers and fibrils.Molecular dynamics Simulations showed that it is possible to generate a covalent ortho-ortho coupling of two tyrosine residues between two 33-mer fragments. Moreover, we present the formation of dityrosine cross-links in 33-mer gliadin peptide catalyzed by horseradish peroxidase and by UV irradiation. It was identified not only 33-mer dityrosine dimer but also stabilized 33-mer oligomers. We have investigated the structural and morphological characteristics of the stabilized dityrosine oligomers by a combination of fluorescence spectroscopy, SDS gel electrophoresis, circular dichroism and electron microscopy. Although, our experiments are in vitro they revealed new features of 33-mer gliadin peptide and the occurrence of dityrosine cross-links under oxidative conditions could represent an important event in gliadin related disorders.