Because of its especially high affinity and binding specificity, the biotin-avidin (or biotin-streptavidin) interaction has been used for several decades as the basis of many laboratory research techniques to label, detect and purify peptide, proteins and other biomolecules. The biotin moiety has a very strong affinity for streptavidin (Kd<10-10 M) and biotinylation of peptides is therefore an efficient method to specifically bind peptides to streptavidin coated surfaces.
Peptide biotinylation can be performed either at the N- or C-terminus. Biotinylation at the N-terminus can be performed directly to the primary-terminal amino group, whereas biotinylation is usually performed at the ε-amino group of an (extra) C-terminal lysine. An important consideration when making a biotinylated peptide is to ensure there is a sufficient spacer arm between the biotin group and the amino acids in the peptide which are expected to interact with a macromolecule (such as an antibody). To avoid sterical hindrance, a linker can be inserted between biotin and the peptide sequence. A hydrophobic straight chain spacer such as the 6-carbon ε-aminohexanoic (Ahx) is frequently applied or a hydrophilic tetrapeptide such as -SGSG- can be inserted. Multiple other spacers and linkers are available and can be applied to meet your specific requirements.
One limitation of the biotin-(strept)avidin interaction in purification applications is that it is essentially irreversible under physiological conditions. Binding is resistant to pH and/or temperature changes, organic solutions and denaturing reagents. Therefore in case a reversible interaction to (strept)avidin is desired, the use of biotin analogs is recommended.
Iminobiotin is an analog of biotin, in which the upper ring structure of D-biotin is replaced with a 2-imino-imidazole structure, causing moderated interaction with the avidin or streptavidin binding sites. This biotin analog can be therefore be used in situations requiring mild dissociation of the (strept)avidin-biotin complex.
Similarly desthiobiotin, a non-sulfur containing biotin analog, can be used. Desthiobiotin binds less tightly to avidin and streptavidin than biotin but nonetheless provides a high level of specificity. Moreover it is less prone to oxidation.
Selected references for Biotinylated Peptides
Aw-Yong et al: PLoS ONE (2016) – PMID 27806091. Immunodominant IgM and IgG Epitopes Recognized by Antibodies Induced in Enterovirus A71-Associated Hand, Foot and Mouth Disease Patients.
Boes et al: Plant Biotechnol. J (2015) – PMID 25236489. Detailed functional characterization of glycosylated and nonglycosylated variants of malaria vaccine candidate PfAMA1 produced in Nicotiana.
Gedvilaite et al: Viruses (2015) – PMID 26230706. Evaluation of Trichodysplasia Spinulosa-Associated Polyomavirus Capsid Protein as a New Carrier for Construction of Chimeric Virus-Like Particles.