Reactivity of fibrinogen and fibrinopeptide A containing fibrinogen fragments with antisera to fibrinopeptide A

Two antisera used in the radioimmunoassay for human fibrinopeptide A (FPA) which appear to have different immunochemical specificities have been tested for cross-reactivity with fibrinogen and with three fragments of fibrinogen which contain the FPA sequence. These fragments were the three-chain, NH...

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Bibliographic Details
Published in:Biochemistry (Easton) 1976-03, Vol.15 (6), p.1203-1209
Main Authors: Canfield, Robert E, Dean, Jurrien, Nossel, Hymie L, Butler, Vincent P, Wilner, George D
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Amino Acids - analysis
Animals
Cross Reactions
Fibrinogen
Peptide Fragments - analysis
Peptide Fragments - immunology
Rabbits - immunology
Radioimmunoassay
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Summary:Two antisera used in the radioimmunoassay for human fibrinopeptide A (FPA) which appear to have different immunochemical specificities have been tested for cross-reactivity with fibrinogen and with three fragments of fibrinogen which contain the FPA sequence. These fragments were the three-chain, NH2-terminal disulfide knot (N-DSK) produced by CNBr cleavage of fibrinogen, the reduced, carboxymethyl Aalpha chain portion of the N-DSK, and fragment E produced by plasmin digestion of fibrinogen. One antiserum (R-2) showed high specificity for free FPA and less than 2% cross-reactivity with fibrinogen or the FPA-containing fragments. The other antiserum (R-33) possessed a much higher degree of cross-reactivity with the FPA-containing fragments. Synthetic and native fibrinopeptides were found to be indistinguishable in the assay system with either antiserum. As a result of these studies, an hypothesis has been developed concerning the nature of the antigenic determinants on FPA which favor measurement of free FPA and limit cross-reactivity with larger, FPA-containing peptides.
ISSN:0006-2960
1520-4995
DOI:10.1021/bi00651a004