The complex formation between biotin and avidin or streptavidin is one of the strongest and most specific non-covalent interactions of a low-molecular weight compound with a protein. In practical use, the non-glycosylated streptavidin is preferred over the glycoprotein avidin as it shows less unspecific binding. Both can complex up to four biotin molecules. Binding occurs rapidly and the complex is stable at pH 3-13 and at increased temperature. Only strong denaturating agents will destroy it.
Biotinylation of a bioactive peptide allows its detection, isolation, enrichment or purification by affinity capture, albeit the incorporation of a biotin label lowers the solubility of the target compound.
Biotin tags can be easily introduced during peptide synthesis or post-synthetically, even in unprotected peptides, e.g. by using D-Biotinyl-OSu (Biotin-NHS, Q-1760). Applying this most popular biotinylation reagent, selective N-terminal biotinylation in the presence of lysine can be achieved by pH-control (pH ca. 6.5). Insertion of a polar spacer between the tag and the peptide (as AEEAc in G-4740) increases the solubility of the conjugate and reduces steric hindrance allowing a tighter binding to (strept)avidin.
Lys(biotinyl) derivatives allow a C-terminal or intra-peptidic tag to be introduced without modifying the synthetic protocol. As an alternative to Lys, the reaction of free Cys with maleimido derivatives of biotin allows selective labelling at any position.
Besides building blocks for introducing the affinity tag including Fmoc-Lys(biotinyl)-OH coupled to Wang resin (D-2705), Bachem offers a vast choice of N-terminally biotinylated bioactive peptides as well as custom biotinylation.
Biotinylated building blocks
- Q-1760 D-Biotinyl-OSu
- G-4740 Biotinyl-AEEAc-AEEAc-OH
- G-4485 Biotinyl-Gly-Gly-OH
- E-3435 H-Lys(biotinyl)-OH
- E-3430 H-Lys(biotinyl)-NH2
- A-3770 Boc-Lys(biotinyl)-OH (Boc-Biocytin)
- B-2580 Fmoc-Lys(biotinyl-ε-aminocaproyl)-OH
- B-2640 Fmoc-Biocytin (Fmoc-Lys(biotinyl)-OH)
- B-3550 Fmoc-D-Biocytin (Fmoc-D-Lys(biotinyl)-OH)
- D-2705 Fmoc-Lys-(biotinyl)-® (200-400 mesh)
Selected biotinylated peptides
- H-5642 Biotinyl-Amyloid β-Protein (1-42)
- H-5736 Biotinyl-Angiotensin I
- H-6674 Biotinyl-Hepcidin-25 (human)
- H-6692 Biotiny-LL-37
- H-5672 Biotinyl-α-MSH
- H-6242 Biotinyl-Somatostatin 14 (Biotinyl-SRIF)
- H-5714 Biotinyl-(Arg8)-Vasopressin
- N-1840 Biotinyl-Val-Ala-DL-Asp-fluoromethylketone (Biotinyl-VAD-FMK)
Contact Bachem for more information.