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Updated: Jun 19, 2026

Measurement of Factor V Activity in Human Plasma Using a Microplate Coagulation Assay
Published on: September 9, 2012
Factor VIII/von Willebrand factor protein. Galactose a cryptic determinant of von Willebrand factor activity
Abstract:
The normal Factor VIII/von Willebrand factor protein has the ability to agglutinate or aggregate normal platelets in the presence of ristocetin (von Willebrand factor activity). Removal of greater than 95% of the sialic acid from this protein by neuraminidase did not affect the von Willebrand factor or procoagulant activity. However, oxidation of the penultimate galactose of the asialo Factor VIII/von Willebrand factor protein with galactose oxidase resulted in a progressive loss of von Willebrand factor activity with no effect on procoagulant activity. Reduction of the 6-aldehydo intermediate by potassium borohydride caused full regeneration of von Willebrand factor activity. These studies confirm the identification of the intact penultimate galactose moiety as a critical determinant of von Willebrand factor activity.
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