Discovery of new inhibitor for the protein arginine deiminase type 4 (PAD4) by rational design of α-enolase-derived peptides

• Main Authors: Ahmad Nadzirin, Izzuddin, Leow, Adam Thean Chor, Salleh, Abu Bakar, Abdul Rahman, Mohd Basyaruddin, Tejo, Bimo Ario
• Format: Article
• Language: English
• Published: Elsevier 2021
• Online Access: http://psasir.upm.edu.my/id/eprint/96755/1/ABSTRACT.pdf; http://psasir.upm.edu.my/id/eprint/96755/; https://www.sciencedirect.com/science/article/pii/S1476927121000542
• Institution: Universiti Putra Malaysia

Rheumatoid arthritis (RA) is an inflammatory autoimmune disease affecting about 0.24 % of the world population. Protein arginine deiminase type 4 (PAD4) is believed to be responsible for the occurrence of RA by catalyzing citrullination of proteins. The citrullinated proteins act as autoantigens by stimulating an immune response. Citrullinated α-enolase has been identified as one of the autoantigens for RA. Hence, α-enolase serves as a suitable template for design of potential peptide inhibitors against PAD4. The binding affinity of α-enolase-derived peptides and PAD4 was virtually determined using PatchDock and HADDOCK docking programs. Synthesis of the designed peptides was performed using a solid phase peptide synthesis method. The inhibitory potential of each peptide was determined experimentally by PAD4 inhibition assay and IC50 measurement. PAD4 assay data show that the N-P2 peptide is the most favourable substrate among all peptides. Further modification of N-P2 by changing the Arg residue to canavanine [P2 (Cav)] rendered it an inhibitor against PAD4 by reducing the PAD4 activity to 35 % with IC50 1.39 mM. We conclude that P2 (Cav) is a potential inhibitor against PAD4 and can serve as a starting point for the development of even more potent inhibitors.