Blue-fluorescent antibodies

The forte of catalytic antibodies has resided in the control of the ground- state reaction coordinate. A principle and method are now described in whic h antibodies can direct the outcome of photophysical and photochemical even ts that take place on excited-state potential energy surfaces. The key comp onent is a chemically reactive optical sensor that provides a direct report of the dynamic interplay between protein and Ligand at the active site. To illustrate the concept, we used a trans-stilbene hapten to elicit a panel of monoclonal antibodies that displayed a range of fluorescent spectral beh avior when bound to a trans-stilbene substrate. Several antibodies yielded a blue fluorescence indicative of an excited-state complex or "exciplex" be tween trans-stilbene and the antibody. The antibodies controlled the isomer ization coordinate of trans-stilbene and dynamically coupled this manifold with an active-site residue. A step was taken toward the use of antibody-ba sed photochemical sensors for diagnostic and clinical applications.