Authors: S. Corry, L-Q Ying, B. Branchaud
Affilation: Life Technologies, United States
Pages: 151 - 154
Keywords: biotin, streptavidin, binding, affinity, kinetics, tunable, responsive
The binding between streptavin and biotin, which is one of the strongest non-covalent interactions known in nature, is used ubiquitously in molecular biology. However, when a biotinylated molecule is captured for testing purposes and cannot be easily removed from the streptavidin-biotin complex, the extreme binding strength is a disadvantage. Here we present several biotin analogs that have attenuated affinities for streptavidin. A successfully engineered streptavin-biotin system for capture and release of sensitive biomaterials must have 1) a strong binding interaction, meaning a low equilibrium binding constant, KD; 2) a fast on-rate, ka, permitting formation of a binding complex within short incubation times; 3) a fast off-rate, kd, permitting rapid re-equilibration of the system upon introducing a competitive binder. Avidity effects arising from streptavidin’s polyvalency violate several assumptions of basic models for determining affinity, requiring development of novel analytical techniques to characterize kinetic parameters. The most economical fabrication methods involve a convergence of imposing long-range order via externally controlled top-down patterning and nanoscale structure (short-range order) via bottom-up self-assembly, in which streptavidin and biotin are frequently employed as self-assembling molecules. Biotin analogs with modulated affinities will add versatility, flexibility, and precision to the molecular- and nano-fabrication toolbox.