The biotin-streptavidin system

Figure 3.7 The biotin-streptavidin system for enantioselective hydrogenation.

Dixit, S. B. Chipot, C., Can absolute free energies of association be estimated from molecular mechanical simulations The biotin-streptavidin system revisited, J. Phys. Chem. A 2001,105, 9795-9799. 

S. Busse, E. Scheumarm, B. Menges, and S. Mittler, "Sensitivity Studies for Specific Binding Reactions using the Biotin/Streptavidin System by Evanescent Optical Methods " Biosensors Bioelectronics 17, 704 - 710 (2002). 

For greatest sensitivity, the biotin-streptavidin system should be used in antibody detection, especially since proteins separated in 2D are often more difficult to detect than when separated in ID... 

Kakabakos SE, Khosravi MJ. Direct time-resolved fluorescence inunimoassay of progesterone in serum involving the biotin streptavidin system and the iimnobihzed-antibody approach. Clin. Chem. 1992 38 725-730. 

The biotin-streptavidin system provides a "textbook case" of the relative free energies of the binding of biotin, aminobiotin, and thiobi-otin, as illustrated in Table 4.5. First, the calculated relative free energies are in reasonable agreement with experiment thiobiotin is calculated and observed to bind 10 or 4 kcal/ mol more weakly to streptavidin than biotin, and iminobiotin is calculated and observed to bind 10 or 7 kcdmol more weakly than biotin. What is more interesting are the energy components. Thiobiotin is easier to desolvate than biotin by kcal/mol (AG ni J but... 

The feasibility of the assay was demonstrated by the calibration curve shown in Fig. 8.4b. The range of sensitivity for the assay is between 10 and 240 ng mL" nortriptyline. This is entirely compatible with concentrations of medications in the blood, which are in the microgram mL range (cf Table 8.2). To increase the sensitivity of the assay, signal amplification was obtained using the biotin/ streptavidin system. The principle of this 4-step assay is shown in Fig. 8.5. This is... 

The critical point for all of these sensors is the specificity for the target species, with different oxidizing agents, e.g. ozone, O3, leading to similar changes. The specificity is also a critical issue for biosensors but here the lock and key principle of certain receptors, such as the biotin streptavidin system, can be exploited (78). 

The well-studied biotin-streptavidin system with its extremely high binding affinity (K 10 M" ) is chosen to illustrate the attributes of these LSPR-based nanoscale affinity biosensors. The biotin-streptavidin system has been studied in great detail by SPR spectroscopy and serves as an excellent model system for the LSPR nanosensor. Streptavidin, a tetrameric protein, can bind up to four biotinylated molecules (i.e. antibodies, inhibitors, nucleic acids, etc.) with minimal impact on its biological activity and, therefore, will provide a ready pathway for extending the analyte accessibility of the LSPR nanobiosensor. 

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