Biotin conjugation properties

FIG. 6 Successive coupling of two different biotinylated compounds with the DNA-STV conjugates 2 [33]. In a first step, a macromolecular functional component (FC, represented by the shaded ellipse), such as a biotinylated enzyme or oligonucleotide, is coupled. In a second step, a biotinylated low-molecular-weight modulator M, represented by the shaded sphere) is coupled to the remaining free biotin-binding sites. The modulator is used to modify the conjugate s hybridization properties or to supplement its functionality. 

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... 

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