Pitfalls in the detection of citrullination and carbamylation

Publication date: Available online 2 December 2017 Source:Autoimmunity Reviews Author(s): M.K. Verheul, P.A. van Veelen, M.A.M. van Delft, A. de Ru, G.M.C. Janssen, T. Rispens, R.E.M. Toes, L.A. Trouw Carbamylation and citrullination are both post-translational modifications against which (auto)antibodies can be detected in sera of rheumatoid arthritis (RA) patients. Carbamylation is the chemical modification of a lysine into a homocitrulline, whereas citrullination is an enzymatic conversion of an arginine into a citrulline. It is difficult to distinguish between the two resulting amino acids due to similarities in structure. However, differentiation between citrulline and homocitrulline is important to understand the antigens that induce antibody production and to determine which modified antigens are present in target tissues. We have observed in literature that conclusions are frequently drawn regarding the citrullination or carbamylation of proteins based on reagents that are not able to distinguish between these two modifications. Therefore, we have analyzed a wide spectrum of methods and describe here which method we consider most optimal to distinguish between citrulline and homocitrulline. We have produced several carbamylated and citrullinated proteins and investigated the specificity of (commercial) antibodies by both ELISA and western blot. Furthermore, detection methods based on chemical modifications, such as the anti-modified citrulline-“Senshu” m...
Source: Autoimmunity Reviews - Category: Allergy & Immunology Source Type: research