Factor VIII of Small Molecular Weight and its Aggregation

Summary. Work on the disaggregation of factor VIII into sub‐units has been extended and it is shown that factor VIII of small molecular weight may be aggregated to a high molecular weight species probably identical to the nod unreacted factor. In addition some practical modifications were introduced to improve yield and reproducibility. The reaction of dithiothreitol and high concentrations of saline were compared using both human and bovine factor VIII. Small factor VIII which was produced had a molecular weight of 230 000 and the act of disaggregation illustrated a clear difference in behaviour between active factor VIII and factor VIII related antigen. These results may be considered to oppose the hypothesis that factor VIII related antigen is the protein carrier of factor VIII.