Phagemid Vector - Efficient Tool for Phage Display

Phage display was created by G. Smith in 1985 as a method for presenting polypeptides on the surface of lysogenic filamentous bacteriophages. Since then, this method has become one of the most powerful and widely used laboratory techniques for the study of protein-protein, protein-peptide or protein-DNA interactions, constructing of the antibody and antibody fragments and improving the affinity of proteins to receptors. In this technique, a gene encoding a protein of interest is inserted into a phage coat protein gene, causing the phage to "display" the protein on its outside, resulting in a connection between genotype and phenotype. These displaying phages can then be screened against other proteins, peptides or DNA sequences, in order to detect interaction between the displayed protein and those other molecules. In this way, large libraries of proteins/antibodies can be screened and amplified in an in vitro selection process, which is analogous to natural selection.

For the phage display, it is clear that the first requirement is a suitable vector system designed to display fusion proteins on the surface of the target phage. The phagemid which derived from a coliphage and a plasmid can achieve this requirement. Phagemid carries both a plasmid replication origin allowing isolation of double stranded plasmid from the cytoplasm of cells, and a replication origin usually from a single stranded phage such as f1, fd or M13 which allows the plasmid to enter a single strand replication mode in which only one of the strands is packaged into the virus particle when helper phage is added to the cell. Besides, the double stranded circular DNA of the plasmid form of the vector contains a variety of multiple cloning sites which make it convenient for DNA recombination, gene manipulation and protein purification.

Creative Biogene, as a leading biotechnology company, can offer you several phagemid vectors that can be used in the phage display to study high-throughput screening of protein-protein interactions, selection of proteins with specific binding properties (high affinity binders), enzyme inhibitor screening, and ligand screening etc.

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