Fig. 1.

Requirements of PAD for reducing agents. a Microtitre plates coated with human fibrinogen were incubated for 3 h at RT with CaCl₂-containing buffer alone, a pool of synovial fluid (SF) from four patients with RA (33 % v/v in buffer) or a pool of serum from five healthy donors (33 % v/v in buffer). rhPAD2 and rhPAD4, mixed at a molar ratio of 1:1, and 1 mM dithiothreitol (DTT) were added as indicated. The catalytic activity of rhPADs was measured by an ELISA detecting citrullination of fibrinogen by means of the mAb 20B2, and is expressed as optical density (OD). b Individual activities of rhPAD2 and rhPAD4 at various concentrations of reduced glutathione (GSH) in buffer containing 10 mM CaCl₂. All data represent the mean and range of duplicate measurements. rhPAD recombinant human peptidylarginine deiminase