MODIFIED DIMERIC STREPTAVIDINS AND USES THEREOF

摘要

The present invention provides novel modified streptavidin proteins, nucleic acids encoding such proteins, and uses of such proteins. Specifically, the invention provides single-chain dimeric streptavidin molecules. The invention also provides modified single-chain streptavidins with altered affinity to biotin and biotin derivatives, such as biotin-4-fluorescein. The modified single-chain dimeric streptavidin proteins can be used in analysis or composite separation either alone or in combination with ordinary streptavidin-biotin systems to visualize and/or separate composites and molecules. The single-chain streptavidin dimers of the invention also allow creating of more stable streptavidin tetramers. The single-chain streptavidin dimers of the invention can further be used as smaller sized functional streptavidin molecules in various in vivo methods, where the size of the conventional tetrameric streptavidin makes the use of such tetramers difficult or impossible. Such in vivo uses include diagnostic imaging and targeting of therapeutic molecules into individuals. The invention further provides methods of preparing and identifying novel modified single-chain streptavidin molecules.