FIG 5.

Mapping epitopes of anti-CD4 Adnectins by SPR. Binding of anti-CD4 Adnectins to CD4-antibody complexes. The indicated anti-CD4 antibodies (the domain [D] of CD4 to which the antibody binds is given in parentheses) were captured onto the chip surface via protein A and used to capture soluble CD4. Anti-CD4 Adnectins were flowed over the CD4-antibody complexes to detect cobinding. On the basis of the number of response units (RU) of CD4 bound to each antibody, a theoretical maximum number of RU for binding was calculated for each Adnectin. The actual level of Adnectin binding to CD4-antibody complexes is presented as a percentage of this theoretical maximum. A high percentage of binding denotes that the Adnectin binds an epitope distinct from that the epitope to which the indicated antibody binds.