Conformation of Fibrinogen: Calorimetric Evidence for a Three-Nodular Structure
AUTOR(ES)
Donovan, John W.
RESUMO
Solutions of fibrinogen show two endothermal (denaturing) transitions, at 61° and at 100°, when heated in a differential scanning calorimeter. Similar transitions are observed for a mixture of the fragments D and E obtained by limited proteolysis of fibrinogen. Isolated fragment E shows only a single transition, at 97°. The independent thermal denaturation of these portions of fibrinogen supports the three-nodular model proposed for fibrinogen. The D and E subunits retain their characteristic denaturation behavior when fibrinogen is clotted by thrombin addition, but over a period of about one hundred times the clotting time, the denaturation temperature of the D subunit increases by 9° and its enthalpy of denaturation by one-third. Since this change takes place in the absence of Factor XIII activity, and its rate is proportional to thrombin concentration, it is presumed to be mediated by a proteolytic cleavage distinct from those which liberate the A and B fibrinopeptides.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=434341Documentos Relacionados
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