H-dependent multimolecular complex formation with PRT and Lys. (A-B) Schematic representation of PF4 and H interactions as previously reported.5 PF4 in solution, in the absence of H, shows minimal light aborption (left side of curve in panel A) and displays positive charge (top part of curve in panel B). With increasing amounts of H (x-axis), charge neutralization occurs resulting in complexes of increasing size (peak in panel A) and neutral charge (inflection point in panel B). Addition of H beyond the concentration required for peak complexes results in complexes of reduced size (right side of curve in panel A) and increasingly negative charge (bottom of curve in panel B). (C-D) PRT (250-31 μg/mL) was incubated with increasing concentrations of H. Light absorption (panel C) and ζ-potential (panel D) were measured. E-F: Lys (1000-125 μg/mL) was incubated with increasing concentrations of H. Light absorption (panel E) and ζ-potential (panel F) were measured. Data are representative of 3 or more independent experiments.