Partial identification of the epitope on D-dimer for monoclonal antibody, DD-3B6/22.
This study provides new information about the recognition site on fibrin for DD-3B6/22, a monoclonal antibody used in the diagnosis of thrombotic disease and proposed as a delivery agent for radioisotopes to visualize thrombi in situ. Preliminary chemical modification and proteolytic digestion of D-dimer revealed key residues in the interaction of D-dimer with its diagnostic antibody DD-3B6/22. Following the initial survey, thermolysin was used to produce digestion fragments for more specific sequence analysis. The gamma-polypeptide chain of D-dimer was confirmed as a recognition site for the antibody, with the residues S86RK88 being implicated in binding, and a second, novel site of antibody interaction was identified on the alpha-polypeptide as D105NTYNR110. Based on evidence from this study and from a previous investigation of the DD-3B6/22 binding site on D-dimer (Devine and Greenberg), a model for the DD-3B6/22 binding site is proposed to comprise regions from parts, at or near the N-terminus, of at least two different subunits: one region on the alpha-polypeptide chain of one D monomer and another region on the gamma-polypeptide chain of an adjacent D monomer. The model is discussed in the context of the predicted secondary and tertiary structure of D-dimer.
Wylie
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FG
Centre for Molecular Biotechnology, School of Life Science, Queensland University of Technology, Brisbane, Australia. f.wylie@cmcb.uq.edu.au
Walsh
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TP
D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000276:immunology*; D001665:Binding Sites; D018604:Epitope Mapping; D005338:Fibrin Fibrinogen Degradation Products / Q000276:immunology*; D006801:Humans; D008969:Molecular Sequence Data; D013820:Thermolysin / Q000378:metabolism
D000911:Antibodies, Monoclonal; D005338:Fibrin Fibrinogen Degradation Products; C036309:fibrin fragment D; D013820:Thermolysin