Biopanning is an affinity selection technique which selects for
peptide
Peptides are short chains of amino acids linked by peptide bonds. A polypeptide is a longer, continuous, unbranched peptide chain. Polypeptides that have a molecular mass of 10,000 Da or more are called proteins. Chains of fewer than twenty am ...
s that bind to a given
target
Target may refer to:
Warfare and shooting
* Shooting target, used in marksmanship training and various shooting sports
** Bullseye (target), the goal one for which one aims in many of these sports
** Aiming point, in field artille ...
. All peptide sequences obtained from biopanning using combinatorial peptide libraries have been stored in a special freely available database name
BDB This technique is often used for the selection of
antibodies
An antibody (Ab) or immunoglobulin (Ig) is a large, Y-shaped protein belonging to the immunoglobulin superfamily which is used by the immune system to identify and neutralize antigens such as bacteria and viruses, including those that caus ...
too.
Biopanning involves 4 major steps for peptide selection. The first step is to have
phage display
Phage display is a laboratory technique for the study of protein–protein, protein–peptide, and protein–DNA interactions that uses bacteriophages (viruses that infect bacteria) to connect proteins with the genetic information that encodes ...
libraries prepared. This involves inserting foreign desired
gene
In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...
segments into a region of the
bacteriophage
A bacteriophage (), also known informally as a phage (), is a virus that infects and replicates within bacteria. The term is derived . Bacteriophages are composed of proteins that Capsid, encapsulate a DNA or RNA genome, and may have structu ...
genome, so that the peptide product will be displayed on the surface of the bacteriophage virion. The most often used are genes pIII or pVIII of
bacteriophage M13.
[Smith GP, and Scott JK. ''Libraries of peptides and proteins displayed on filamentous phage''. ]Methods in Enzymology
''Methods in Enzymology'' is a book-series of scientific publications focused primarily on research methods in biochemistry by Academic Press, created by Sidney P. Colowick and Nathan O. Kaplan.
Content
Historically, each volume has centered o ...
. 1993. 217:228-257
The next step is the capturing step. It involves conjugating the phage library to the desired target. This procedure is termed panning. It utilizes the binding interactions so that only specific peptides presented by bacteriophage are bound to the target. For example, selecting antibody presented by bacteriophage with coated
antigen
In immunology, an antigen (Ag) is a molecule, moiety, foreign particulate matter, or an allergen, such as pollen, that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune response.
...
in microtiter plates.
The washing step comes after the capturing step to wash away the unbound phages from solid surface. Only the bound phages with strong affinity are kept. The final step involves the elution step where the bound phages are eluted through changing of pH or other environment conditions.
The end result is the peptides produced by bacteriophage are specific. The resulting filamentous phages can infect
gram-negative
Gram-negative bacteria are bacteria that, unlike gram-positive bacteria, do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. Their defining characteristic is that their cell envelope consists ...
bacteria once again to produce phage libraries. The cycle can occur many times resulting with strong affinity binding peptides to the target.
References
{{reflist, 1
Biochemistry methods