The effects of guanidine HCl on proteolytic susceptibility of the recombinant vWF. (A) Difference in size reduction kinetics, represented by increased normalized peak distance on densitometric tracings of an SDS 1.5% agarose gel, of purified recombinant WT vWF in 1.25 mol/L guanidine HCl (WT/gdn, □) or R834W vWF mutant in TBS (R834W, •) incubated with 1 U/mL proteinase. The reaction was stopped at designated intervals by 10 mmol/L EDTA and SDS agarose gel electrophoresis was performed. (B) Guanidine HCl-dependent size reduction, represented by increased normalized peak distance on densitometric tracings of SDS 1.5% agarose gels. Purified recombinant WT vWF (▪) and R834W vWF mutant (□) were treated with designated concentrations of guanidine HCl before incubation with the plasma proteinase at 1/10 dilution. The reaction was stopped at 30 minutes by 10 mmol/L EDTA. *P < .05, **P < .2.