Recombinant kininogen. (A) Schematic diagrams of human LK (top) and HK (bottom) showing domain structure and the disulfide bond connecting the N- and C-termini. The bradykinin sequence is contained within the common D4 domain. (B) Sequence of bradykinin (top; light blue) and kallidin (middle; green) in wild-type (WT) kininogens. Also shown is the position of Lys at position 379 in the HK and LK variants HK-Lys³⁷⁹ and LK-Lys³⁷⁹, respectively (bottom; red). The asterisk indicates a proline residue (Pro³⁸³) that becomes oxidized during expression or purification of the recombinant kininogens (supplemental Figure 5). (C) Sodium dodecyl sulfate– polyacrylamide gel electrophoresis of purified plasma-derived and recombinant kininogens. Samples (2 μg) of plasma-derived HK or LK (PL), recombinant HK/LK-Met³⁷⁹ (WT), and recombinant HK/LK-Lys³⁷⁹ (379) underwent electrophoresis on an 8% polyacrylamide nonreducing gel, followed by staining with Coomassie blue. Positions of the molecular mass standard in kilodaltons are shown at the left of the figure.