Oxidation of proline decreases immunoreactivity and alters structure of barley prolamin
Xin Huang1, Tuula Sontag-Strohm1, Frederick L Stoddard1
1Department of Food and Environmental Sciences, University of Helsinki, Agnes Sjöberginkatu 2, PL 66, Helsinki FI-00014, Finland.
Abstract:
Elimination of celiac-toxic prolamin peptides and proteins is essential for Triticeae products to be gluten-free. Instead of enzymatic hydrolysis, in this study we investigated metal-catalyzed oxidation of two model peptides, QQPFP, and PQPQLPY, together with a hordein isolate from barley (Hordeum vulgare L.). We established a multiple reaction monitoring (MRM) LC-MS method to detect and quantify proline oxidation fragments. In addition to fragmentation, aggregation and side chain modifications were identified, including free thiol loss, carbonyl formation, and dityrosine formation. The immunoreactivity of the oxidized hordein isolate was considerably decreased in all metal-catalyzed oxidation systems. Cleavage of peptides or protein fragments at the numerous proline residues partially accounts for the decrease. Metal-catalyzed oxidation can thus be used in the modification and elimination of celiac-toxic peptides and proteins.
Related Concept Videos
Protein Denaturation
Amyloid Fibrils
Amyloid deposits were observed as early as 1639 in the liver and the spleen. In 1854, Rudolph Virchow performed iodine staining,...
Protein Folding Quality Check in the RER
Covalently Linked Protein Regulators
These groups modify specific amino acids in a protein....
Oxidation of Alcohols
The process of oxidation in a chemical reaction is observed in any of the three forms:
Protein Modifications in the RER
Broadly, these modifications can be categorized into four main categories — glycosylation, formation of disulfide bonds, assembly of protein subunits, and specific proteolytic cleavages like removal of signal...


