Coverage of HDX-MS of FIXa–FVIIIa complex. HDX-MS experiments involved 9 time points, and changes in deuterium uptake were rated as prominent when all 9 time points displayed a reduction in deuterium uptake per peptide of ≥0.35 Da for the entire peptide. These were mapped on FIXa sequence in red. Changes were rated moderate when 4 to 8 time points showed reduction by ≥0.35 Da were mapped in yellow. No appreciable change was designated by peptides with less than 3 time points with ≥0.35 Da difference in deuterium uptake. FIXa numbering is assigned underneath the sequence, with chymotrypsin numbering between brackets. FIXa domains and regions are also indicated. Gla residues are indicated in black bold characters. Glycosylation sites are shown in red.