IngentaConnect Electrospray ionization mass spectrometry identification of fibri...

Authors: Fellowes, Andrew P.¹; Brennan, Stephen O.¹; Ridgway, Hayley J.¹; Heaton, David C.²; George, Peter M.¹

Source: British Journal of Haematology, Volume 101, Number 1, April 1998 , pp. 24-31(8)

Abstract:

Fibrinogen Banks Peninsula was identified in the mother of a patient referred for investigation following recurrent epistaxis. Coagulation tests revealed prolonged thrombin and reptilase times and a decreased functional fibrinogen level. Thrombin-catalysed release of fibrinopeptides A and B was normal, and no abnormalities were detected by DNA sequencing of the regions encoding the thrombin cleavage sites in the Aα and Bβ genes. Reducing SDS-PAGE and reverse-phase HPLC analysis of purified fibrinogen chains were normal, as was electrospray ionization mass spectrometry (ESI-MS) analysis of isolated Aα and Bβ chains. However ESI-MS revealed a mass of 48 345 D for the isolated γ chains, 31 D less than the measured mass of control chains (48 376 D). Since normal and abnormal γ chains were not resolved, this implies a 60-62 D mass decrease in 50% of the molecules. A 60 D decrease was confirmed when DNA sequencing indicated heterozygosity for a mutation of Tyr→Cys at codon 280 of the γ chain gene. Fibrin monomer polymerization revealed a delayed lag phase and reduced final turbidity and although factor XIIIa crosslinking of fibrinogen was normal, it is likely that this delay is due to impaired D:D self association. Recent crystallographic studies show residues γ280 and γ275 make contact across the D:D interface, suggesting a similar mechanism for the polymerization defects in fibrinogens Banks Peninsula and Tokyo II (γ275Arg→Cys).

Keywords: dysfibrinogenaemia; gamma chain; electrospray mass spectrometry; PCR; defective polymerization

Document Type: Original article

DOI: 10.1046/j.1365-2141.1998.00663.x

Affiliations: 1: Molecular Pathology Laboratory, 2: Department of Haematology, Canterbury Health Laboratories, Christchurch, New Zealand

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Electrospray ionization mass spectrometry identification of fibrinogen Banks Peninsula (γ280Tyr→Cys): a new variant with defective polymerization