Site-directed PEGylation of A1 domain residues and effect on prothrombin processing. (A) Cartoon representation of full-length pseutarin C, colored as in Figure 2, indicating the positions of mutated and PEGylated residues on the A1 domain, shown as magenta balls. (B) Effects of both Cys mutation and PEGylation on thrombin generation were tested by chromogenic (top) and SDS-PAGE (bottom) assays (labeled as in Figure 2). II, prothrombin; F1.2-L, F1.2+light chain; IIa-H, thrombin heavy chain; mAu, milli–absorbance unit.