THERAPEUTIC FRAGMENTS OF VON WILLEBRAND FACTOR

Processes for preparing aqueous solutions of cysteine-altered von Willebrand Factor fragment which are substantially free of aggregate and capable of therapeutic use for treating thrombosis are provided. The claimed process comprises providing an aqueous solution of vWF fragment and denaturant and containing undesired contaminants, said solution having an acidic pH; separating said contaminants from said solution by contacting said solution with an affinity chromatography medium to which said vWF fragments adhere; eluting said vWF fragment from said affinity chromatography medium in the presence of the denaturant; and separating the eluted fragment from said denaturant while maintaining the aqueous solution of the fragment at a pH of about 2.5 to less than about 5.5 to increase monomerization of, and decrease aggregation of, said fragment, thereby forming an aqueous solution of vWF fragment which is substantially free of aggregate.