300905 Study Guide - Final Guide: Tissue Transglutaminase, Coeliac Disease, Deamidation

• School: UWS
• Department: University of Western Sydney
• Course: 300905
• Professor: anonymous

Document Summary

Tissue transglutaminase modifies gluten peptides into a form that may stimulate the immune system more effectively. These peptides are modified by ttg in two ways: deamidation, transamidation. Deamidation is the reaction by which a glutamate residue is formed by cleavage of the epsilon-amino group of a glutamine side chain. Transamidation, which occurs three times more often than deamidation, is the cross-linking of a glutamine residue from the gliadin peptide to a lysine residue of ttg in a reaction that is catalysed by the transglutaminase. Crosslinking may occur either within or outside the active site of the enzyme. The latter case yields a permanently covalently linked complex between the gliadin and the ttg. This results in the formation of new epitopes believed to trigger the primary immune response by which the autoantibodies against ttg develop. Stored biopsies from people with suspected coeliac disease have revealed that autoantibody deposits in the subclinical coeliacs are detected prior to clinical disease.