Improved affinity of engineered streptavidin for the Strep-tag II peptide is due to a fixed open conformation of the lid-like loop at the binding site.

ABSTRACT: The Strep-tag II is a nine-amino acid peptide that was developed as an affinity tool for the purification of corresponding fusion proteins on streptavidin columns. The peptide recognizes the same pocket of streptavidin where the natural ligand is normally bound so that biotin or its chemical derivatives can be used for competitive elution. We report here the crystal structures of the streptavidin mutants '1' and '2,' which had been engineered for 10-fold higher affinity towards the Strep-tag II. Both streptavidin mutants carry mutations at positions 44, 45, and 47, that is, in a flexible loop region close to the binding site. The crystal structures of the two apo-proteins and their complexes with the Strep-tag II peptide were refined at resolutions below 2 A. Both in the presence and absen

SUBMITTER: Korndorfer IP 

PROVIDER: S-EPMC2373521 | biostudies-literature | 2002 Apr

REPOSITORIES: biostudies-literature