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Fibrinogen Seattle releases half the normal amount of fibrinopeptide B
Abstract:
Fibrinogen Seattle, a clinically silent, slow-clotting dysfibrinogen, releases 50% of the normal amount of fibrinopeptide B as assessed by amino acid analysis. The reduced dysfibrin exhibited equal quantities of chains with B beta- and beta-charge mobility on polyacrylamide gel electrophoresis in 2 M urea at low pH. By these same techniques, the release of fibrinopeptide A was normal. Clots formed by repolymerizing the thrombin and batroxobin dysfibrin monomers showed a maximal turbidity that was lower than normal. Fibrinogen Seattle was indistinguishable from normal fibrinogen by radial immunodiffusion and immunoelectrophoresis. Degradation by plasmin and transamination by factor XIIIa were normal. The characteristics of fibrinopeptide release by fibrinogen Seattle distinguish it from other reported dysfibrinogens.
Insights
Fibrinogen Seattle is a slow-clotting dysfibrinogen that releases half the normal amount of fibrinopeptide B. This unique characteristic distinguishes it from other dysfibrinogens.
Area of Science:
- Biochemistry
- Hematology
- Molecular Biology
Background:
- Dysfibrinogenemia is a group of inherited bleeding disorders characterized by abnormal fibrinogen function.
- Fibrinogen Seattle is a rare dysfibrinogen variant presenting with clinically silent, slow clot formation.
- Understanding the molecular defects in dysfibrinogen variants is crucial for diagnosing and managing bleeding disorders.
Purpose of the Study:
- To characterize the molecular defect in Fibrinogen Seattle.
- To investigate the fibrinopeptide release patterns and clot formation properties of Fibrinogen Seattle.
- To compare Fibrinogen Seattle with normal fibrinogen and other dysfibrinogen variants.
Main Methods:
- Amino acid analysis to quantify fibrinopeptide release.
- Polyacrylamide gel electrophoresis (PAGE) in 2 M urea at low pH to assess chain mobility.
- Turbidity measurements to evaluate clot formation kinetics.
- Radial immunodiffusion and immunoelectrophoresis for immunologic comparison.
- Assays for plasmin degradation and factor XIIIa transamination.
Main Results:
- Fibrinogen Seattle released 50% of normal fibrinopeptide B, while fibrinopeptide A release was normal.
- Electrophoresis revealed equal quantities of B beta- and beta-chains, suggesting altered B beta-chain processing.
- Repolymerized Fibrinogen Seattle monomers formed clots with lower maximal turbidity compared to normal fibrinogen.
- Fibrinogen Seattle was immunologically indistinguishable from normal fibrinogen and exhibited normal degradation and transamination.
Conclusions:
- Fibrinogen Seattle exhibits a unique defect in fibrinopeptide B release, distinguishing it from other dysfibrinogens.
- The altered fibrinopeptide release impacts clot structure and function, leading to slower clotting times.
- Fibrinogen Seattle serves as a model for understanding structure-function relationships in fibrinogen.