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Azides of Biotin/Desthiobiotin

Azides of biotinylation reagents can be used for the labeling of terminal Alkyne- and strained Alkyne (e.g. DBCO)-labeled biomolecules via Cu(I)-catalyzed Alknye-Azide (CUAAC) or Cu(I)-free strain-promoted Alkyne-Azide Click Chemistry (SPAAC) reaction, respectively.

Labeling of a molecule (e.g. a protein or nucleic acid) with biotin/desthiobiotin is routinely performed for its subsequent affinity purification via streptavidin agarose or detection with fluorescent or HRP-labeled streptavidin. Due to the extremely high affinity of biotin towards streptavidin (KD = 10-15 M), the biotinylated molecule/streptavidin-interaction is essentially irreversible under physiological conditions. Desthiobiotin however, binds less tightly to streptavidin (KD = 10-11 M) and desthiobiotinylated molecules are therefore easily eluted from the complex in the presence of excess Biotin.