Abnormal Fibrinogens IJmuiden (BβArg14→Cys) and Nijmegen (BβArg44→Cys Form Disulfide-Linked Fibrinogen-Albumin Complexes

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 89; no. 8; pp. 3478 - 3482
• Main Authors: Koopman, Jaap, Haverkate, Frits, Grimbergen, Jos, Engesser, Luzia, Novakova, Irena, Anton F. J. A. Kerst, Lord, Susan T.
• Format: Journal Article
• Language: English
• Published: National Academy of Sciences of the United States of America 15.04.1992
• Subjects: Albumins; Antibodies; Biochemistry; Blood plasma; Dimers; Disulfides; Gels; Molecular weight; Molecules; Venoms
• ISSN: 0027-8424; 1091-6490

The molecular defects in two congenital abnormal fibrinogens, IJmuiden and Nijmegen, were determined by sequence analysis of genomic DNA amplified by the polymerase chain reaction. Both fibrinogens were heterozygous, IJmuiden having a BβArg14→Cys substitution and Nijmegen having a BβArg44→Cys substitution. Clotting induced by thrombin or Reptilase was impaired in both fibrinogens, indicating defective fibrin polymerization. Immunoblot analysis of both purified fibrinogens demonstrated that some of the abnormal molecules were linked by disulfide bonds to albumin. In addition, abnormal high molecular weight fibrinogen complexes with Mrs between 600,000 and 700,000 were present. Fibrinogen-albumin and high molecular weight complexes were also detected in the patients' plasmas. Quantative analysis demonstrated that of the total plasma fibrinogen in the IJmuiden patient, 20% was linked to albumin and 10% was present as high molecular weight complexes. In plasma Nijmegen, 13% was linked to albumin and 15% was present as high molecular weight complexes. These results demonstrate that the additional abnormal cysteine in fibrinogens IJmuiden and Nijmegen resulted in the formation of disulfide-linked complexes with other proteins, predominantly albumin. We also found that a significant fraction of the abnormal fibrinogen molecules contained free sulfhydryl groups. These findings complicate interpretation of functional studies of these altered fibrinogens.