title: Discovery of a new class of inhibitors for the protein arginine deiminase type 4 (PAD4) by structure-based virtual screening.
abstract: BACKGROUND
  Rheumatoid arthritis (RA) is an autoimmune disease with unknown etiology. Anticitrullinated protein autoantibody has been documented as a highly specific autoantibody associated with RA. Protein arginine deiminase type 4 (PAD4) is the enzyme responsible for catalyzing the conversion of peptidylarginine into peptidylcitrulline. PAD4 is a new therapeutic target for RA treatment. In order to search for inhibitors of PAD4, structure-based virtual screening was performed using LIDAEUS (Ligand discovery at Edinburgh university). Potential inhibitors were screened experimentally by inhibition assays.
  
  
  RESULTS
  Twenty two of the top-ranked water-soluble compounds were selected for inhibitory screening against PAD4. Three compounds showed significant inhibition of PAD4 and their IC50 values were investigated. The structures of the three compounds show no resemblance with previously discovered PAD4 inhibitors, nor with existing drugs for RA treatment.
  
  
  CONCLUSIONS
  Three compounds were discovered as potential inhibitors of PAD4 by virtual screening. The compounds are commercially available and can be used as scaffolds to design more potent inhibitors against PAD4.
authors.affiliation: Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Malaysia.
authors.forename: Chian Ying
authors.initials: CY
authors.lastname: Teo
authors.forename: Steven
authors.initials: S
authors.lastname: Shave
authors.forename: Adam Leow Thean
authors.initials: AL
authors.lastname: Chor
authors.forename: Abu Bakar
authors.initials: AB
authors.lastname: Salleh
authors.forename: Mohd Basyaruddin Bin Abdul
authors.initials: MB
authors.lastname: Rahman
authors.forename: Malcolm D
authors.initials: MD
authors.lastname: Walkinshaw
authors.forename: Bimo A
authors.initials: BA
authors.lastname: Tejo
mesh_terms: D018501:Antirheumatic Agents / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D001172:Arthritis, Rheumatoid / Q000201:enzymology*; D019295:Computational Biology / Q000379:methods*; D055808:Drug Discovery / Q000379:methods*; D004791:Enzyme Inhibitors / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D006801:Humans; D006867:Hydrolases / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000737:chemistry; D008024:Ligands; D011487:Protein Conformation; D000080002:Protein-Arginine Deiminase Type 4; D000076342:Protein-Arginine Deiminases; D013329:Structure-Activity Relationship
chemical_list: D018501:Antirheumatic Agents; D004791:Enzyme Inhibitors; D008024:Ligands; D006867:Hydrolases; C000629235:PADI4 protein, human; D000080002:Protein-Arginine Deiminase Type 4; D000076342:Protein-Arginine Deiminases