Phage screening

Antibody interaction drug delivery, 9 64 Antibody purification, 14 145 Antibody recognition, recombinant phage screening by, 12 506-507 Anticakes, for sodium nitrite, 22 857 Anticaking agents, 12 31, 63... 

Library individuals can be screened as microunit-bound entities (on-bead screening versus on-phage screening). 

In order to determine whether compounds identified in the primary HTS screen are specific, a counterscreen is required to identify and eliminate false positives that will arise in the primary screen. For protein—protein interaction screens, it is preferable to test an unrelated protein pair that uses the same mode of detection. For our purposes, we adapted a previously described TR-FRET assay that monitors the interaction between bacterial Staphylococcus aureus Dnal and phage protein 77ORF104 (Liu et al., 2004). 

Figure 13.2 Phage display technology and the screening of a library for a protein capable of binding to a desired target molecule. In this simplified example an initial library of three genes is inserted into three phages. One (gene 2) codes for the desired protein. In reality, libraries typically consist of hundreds of thousands/mil-lions of different genes. Refer to text for further details...

More recently, Janda has described the production of a galactopyranosidase antibody in response to hapten [96]. This was designed to accommodate several features of the transition state for glycoside hydrolysis notably a flattened half-chair conformation and substantial sp2 character at the anomeric position. Some 100 clones were isolated in response to immunization with [96] and used to generate a cDNA library for display on the surface of phage (Appendix entry 7.3) (Janda et al., 1997). Rather than proceed to the normal screening for turnover, Janda then created a suicide substrate system to trap the catalytic species. 

Figure 21 Hapten 35 and fluorogenic substrates 36-38 used to screen phage displayed Fabs with an aldolase activity.

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