Desthiobiotin is a single-ring, sulfur-free analog of biotin that
binds to streptavidin with nearly equal specificity but less
affinity than biotin (Kd = ***1 vs. ***5M, respectively).
Consequently, desthiobiotinylated proteins can be eluted readily
and specifically from streptavidin affinity resin using mild
conditions based on competitive displacement with free biotin. For
pull-down experiments with biological samples, this soft-release
characteristic of desthiobiotin also helps to minimize
co-purification of endogenous biotinylated molecules, which remain
bound to streptavidin upon elution of the target protein complexes
with free biotin.
