The Role of Fibrinogen Aa Chains in ADP-tnduced Platelet Aggregation in the Presence of Fibrinogen Molecules Containing “y’Chains
نویسندگان
چکیده
Human plasma fibrinogen (Fgn) is heterogenous with respect to the size of its ‘y chains. which differ in that residues 408 to 41 1 of #{176}y chains (93% of total) are replaced in “y’ chains by a unique 20 amino acid sequence (#{176}y to #{176}y ). In this study. we compared the contribution to adenosine diphosphate (ADP)-induced platelet aggregation of the Aa chains in Fgn molecules containing predominantly (fraction 1-2) or exclusively (peak 1 Fgn) “yb chains with that of molecules containing -50% “y’ chains (peak 2 Fgn). Using washed human platelets. we confirmed that the number of peak 2 Fgn molecules binding to platelets in the presence of ADP was about half the number of peak 1 Fgn molecules (18.962 ± 2.298 v 44.366 ± 16,096 molecules per platelet). and that isolated S-carboxymethylated (SCM) ‘YA chains supported ADP-induced platelet aggregation nearly as well as peak 1 Fgn. In contrast, SCM-’y’ chains alone supported aggregation poorly. whereas a
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