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  • Ph.D.™-C7C Phage Display Peptide Library


    The Ph.D.™-C7C Phage Display Peptide Library is based on a combinatorial library of random heptapeptides fused to a minor coat protein (pIII) of M13 phage (1–6). Unlike other Phage Display Libraries from NEB, the randomized sequence is flanked by a pair of cysteine residues. Under nonreducing conditions the cysteines will spontaneously form a disulfide cross-link, resulting in phage display of cyclized peptides. Disulfide-constrained peptide libraries (7) have proven useful in identification of structural epitopes (8,9), mirror-image ligands for D-amino acid targets (10) and leads for peptide-based therapeutics (11). The disulfide-constrained heptapeptides are expressed at the N-terminus of plll, with the first cysteine preceded by an alanine residue and the second cysteine followed by a short spacer (Gly-Gly-Gly-Ser) and then the wild-type plll sequence. The library consist of 109 electroporated sequences amplified once to yield approximately 100 copies of each sequence in 10 µl of the supplied phage.

    Properties and Usage

    Storage Temperature


    Quality Control

    Quality Control Assays

    The following Quality Control Tests are performed on each new lot and meet the specifications designated for the product. Individual lot data can be found on the Product Summary Sheet/Datacard or Manual which can be found in the Supporting Documents section of this page.
    • Functional Test (Epitope Mapping):
      The product is panned against monoclonal antibodies in solution, followed by affinity capture of the antibody-phage complex. After 3 rounds of selection the consensus sequence of the epitope of each antibody is confirmed.
    • Functional Test (Panning):
      The product is panned against Streptavidin with bound phage being eluted with biotin. After 3 rounds of selection, the consensus sequence for streptavidin-binding peptides is confirmed.


    1. Parmley, S.F. and Smith, G.P. (1988). Gene. 73, 305-318.
    2. Smith, G.P. and Scott, J.K. (1993). R. Wu(Ed.), Methods Enzymol.. 217, 228-257. San Diego: Academic Press.
    3. Cortese et al. (1995). Curr. Opin. Biotechnol.. 6, 73-80.
    4. Scott, J.K. and Smith, G.P. (1990). Science. 249, 386-390.
    5. Cwirla, S.E., Peters, E.A., Barrett, R.W. and Dower, W.J. (1990). Proc. Natl. Acad. Sci. USA. 87, 6378-6382.
    6. Devlin, J.J., Panganiban, L.C. and Devlin, P.E. (1990). Science. 249, 404-406.
    7. McLafferty, M.A., Kent, R.B., Ladner, R.C. and Markland, W. (1993). Gene. 128, 29-36.
    8. Hoess, R.H., Mack, A., Walton, H. and Reilly, T.M. (1994). J. Immunol.. 153, 724-729.
    9. Luzzago, A., Felici, F., Tramontano, A., Pessi, A. and Cortese, R. (1993). Gene. 128, 51-57.
    10. Schumacher, T.N.M., Mayr, L.M., Minor, D.L., Milhollen, M.A., Burgess, M.W. and Kim, P.S. (1996). Science. 271, 1854-1857.
    11. Wrighton, N.C. et al. (1996). Science. 271, 458-463.

    Supporting Documents

    Material Safety Datasheets

    The following is a list of Material Safety Data Sheets (MSDS) that apply to this product to help you use it safely. The following file naming structure is used to name these document files: [Product Name] MSDS. For international versions please contact us at info@neb.com.


    The Product Manual includes details for how to use the product, as well as details of its formulation and quality controls. The following file naming structure is used to name these document files: manual[Catalog Number].


    The Product Summary Sheet, or Data Card, includes details for how to use the product, as well as details of its formulation and quality controls. The following file naming structure is used to name the majority of these document files: [Catalog Number]Datasheet-Lot[Lot Number]. For those product lots not listed below, please contact NEB at info@neb.com or fill out the Technical Support Form for appropriate document.
    1. Phage Library Choice
    2. What peptide libraries are available for use with Ph.D.™ Phage Display?
    3. Can a different bacterial strain be used with the Ph.D.™ Phage Display?
    4. No plaques are visible when titering using the Ph.D.™ Phage Display kit.
    5. I am using Ph.D.™ Phage display and the amplified phage titer is low.
    6. I am using Ph.D.™ Phage Display and the phage DNA templates do not yield readable sequence.
    7. I am using Ph.D.™ Phage Display and after 4 or more rounds of panning all clones are wild-type phage (white plaques).
    8. When performing an experiment using Ph.D.™ Phage Display, the ELISA indicates that background binding to the plate is as high as binding to the target.
    9. When using the Ph.D.™ Phage Display, panning yielded a consensus sequence, but no ELISA signal.
    10. I am using Ph.D.™ Phage Display and the streptavidin control experiment did not yield the HPQ consensus sequence.