Functional consequences of an arginine180 to glutamine mutation in factor IX Hilo.

摘要: Factor IX Hilo is a variant factor molecule that has no detectable coagulant activity. The defect in arises from point mutation the gene such protein Arg180 converted to Gln. Activation of by Xla was monitored using fluorescent active site probe p-aminobenzamidine. Normal showed complete activation one hour as determined measuring increase fluorescence when p-aminobenzamidine bound activated IX. even after 24 hours, indicating not exposed. Polyacrylamide gel electrophoresis cleaved light chain plus larger peptide with molecular weight equivalent heavy covalently linked an peptide. Amino terminal amino acid sequencing cleavage only at Arg145-Ala146, Gln180-Val181 bond and thus presence patient plasma responsible for having very long ox brain prothrombin time characteristic severe hemophilia Bm. Patient had 100 seconds Thrombotest kit, significantly prolonged over normal control value 45 seconds. When depleted immunoaffinity column, decreased 41 added back plasma, same affinity or CRM- B patient, prolonged. We conclude Gln results cannot be Xla. Further, our data suggest interacts components extrinsic pathway give time.