Avidin, properties

Agiamamioti and co-workers [72] synthesized a novel biotinylated fluorophore, 10-(2-biotinyloxyethyl)-9-acridone 25 with favorable properties for bioanalytical applications. In aqueous solutions, it displayed high fluorescence ([Pg.37]

Biotin modification reagents are widely used to attach a biotin group to proteins or other molecules for subsequent use in avidin, streptavidin, or NeutrAvidin separations or assays. Traditional biotin compounds containing aliphatic or other hydrophobic linker arms are discussed in detail in Chapter 11. In this section, the biotin-PEG compounds exclusively are discussed due to their unique hydrophilic properties, which include low nonspecific binding character and low immunogenicity. 

Specific binding Use of other specific binding properties staphylococcal protein A, avidin-biotin... 

There are certain specimen preparations that create problems for some of the sandwich methods. Frozen or fresh cell preparations may have inherent avidin-binding properties, as some fixed preparations can have. While this should not preclude the use of these methods, one should be aware of the potential limitations and have alternate methodologies available for confirmatory testing. 

It has been known that adsorption kinetics and/or thermodynamics of proteins depend on the electric or electrochemical properties of solid supports on which the proteins are adsorbed. This has led us to elucidate the effects of electrode potential on the adsorption behavior of avidin on the electrode surface. For this purpose, the electrode potential of a Pt electrode was varied systematically in the range of -0.5-+2.0 V in an avidin solution (pH 7.4). Although the data was somewhat scattered, a general trend was observed that the adsorption of avidin is suppressed by the application of a positive potential (+1.0-+2.0 V). This may be originating from the fact that avidin is a basic protein and has net positive charges in the solution of neutral pH. In the potential range tested, no significant acceleration in the adsorption was induced. 

Biotin is a small vitamin molecule (Mr 244) that binds with highaffinity (kD 10 I5M I) to avidin. Avidin is a larger glycoprotein molecule (Mr 70,000), mostly distributed in egg whites. This protein has the advantage of conjugating with different markers, including peroxidase, fluorescent dyes, colloidal gold, and ferritin. Because of this property it is... 

After use, the electrode surface can be renewed by a simple polishing procedure for further uses, highlighting a clear advantage of this new material with respect to surface-modified approaches such as classical biosensors and other common biological assays. Biotinylated antiatrazine antibodies can be easily immobilized on the surface of the avidin-modified transducer through the avidin-biotin reaction since antibodies can be readily linked to biotin without serious effects on their biological, chemical, or physical properties. Moreover, antiatrazine antibodies can be easily immobilized on the surface of the Protein A-modified transducer without any modification of the antibodies. 

T. Huberman, Y. Eisenberg-Domovich, G. Gitlin, T. Kulik, E.A. Bayer, M. Wilchek and O. Livnah, Chicken avidin exhibits pseudo-catalytic properties. Biochemical, structural, and electrostatic consequences, J. Biol. Chem., 276 (2001) 32031-32039. 

On these bases, proteins like human serum albumin (HSA) and avidin (Av) have been labelled with such complexes. This yields bioconjugates that are strongly luminescent and can be used for recognition purposes [79]. In Table 10 are listed luminescence properties of some selected complexes and related bioconjugates [79]. 

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