Specific blocking to improve biopanning in biological samples such serum and hybridoma supernatants

Screening phage-displayed peptide libraries (biopanning) is an important te chnique for acquiring peptide ligands and for mapping peptide epitopes reco gnized by antibodies (Ab). In biological samples, other materials, not only contaminants but also natural constituents, often interfere with biopannin g. Capture methods use anchoring Abs that reduce the need for purification of the intended panning target from a crude sample. This capture method is analogous to sandwich ELISA. However; when the target molecule concentratio n is low in the initial mixture, the panning of a captured target often yie lds epitopes that bind to the capture antibody rather than the target of in terest. We have developed a methodology that utilizes specific blocking rea gents of the capture Ab to extend the sensitivity and applicability of the capture approach to phage panning. A flowchart is presented to enable the w orker to begin panning with the simplest approach and then to employ sand w ich capture and specific blocking reagents as necessary.