Molecular defects of factor IX Chicago-2 (Arg 145----His) and prothrombin
Madrid (Arg 271----cys): arginine mutations that preclude zymogen
activation
DL Diuguid, MJ Rabiet, BC Furie and B Furie
Division of Hematology/Oncology, New England Medical Center, Boston, MA
02111.
Factor IX Chicago-2 and prothrombin Madrid were purified from patients with
hemophilia B and congenital dysprothrombinemia, respectively. Each protein
displays defects in zymogen activation secondary to the failure to cleave
one of the sessile bonds whose cleavage is necessary for full coagulant
activity. These proteins were isolated by immunoaffinity chromatography
using conformation-specific antibodies directed at either factor IX or
prothrombin. Factor IX Chicago-2 is cleaved abnormally by factor XIa,
yielding a pattern consistent with the failure to cleave the sessile bond
between Arg 145 and Ala 146. Prothrombin Madrid is cleaved abnormally by
factor Xa, yielding a pattern consistent with the failure to cleave the
sessile bond between Arg 271 and Thr 272. Peptide mapping was performed on
reduced and alkylated factor IX, factor IX Chicago-2, prothrombin, and
prothrombin Madrid, and the hydrolysates were separated by high-performance
liquid chromatography. The mutant peptide in factor IX Chicago-2 was
identified by automated Edman degradation as residues 143 through 188 of
factor IX, and had a histidine substituted for arginine at residue 145. The
mutant peptide identified in prothrombin Madrid corresponds to residues 267
through 285 of prothrombin and has the substitution of cysteine for
arginine at residue 271. These mutations, each occurring at arginines, are
identical to those in factor IX Chapel Hill and prothrombin Barcelona.
These results suggest that a limited repertoire of point mutations, many
affecting arginine residues, may be responsible for hereditary defects of
the vitamin K-dependent proteins in patients with normal antigen levels.
Volume 74,
Issue 1,
pp. 193-200,
07/01/1989
Copyright © 1989 by The American Society of Hematology
