Streptavidin as a Scaffold for Light-Induced Long-Lived Charge Separation

Sascha G Keller; Andrea Pannwitz; Hendrik Mallin; Oliver S Wenger; Thomas R Ward

doi:10.1002/chem.201703885

Streptavidin as a Scaffold for Light-Induced Long-Lived Charge Separation

Chemistry. 2017 Dec 19;23(71):18019-18024. doi: 10.1002/chem.201703885. Epub 2017 Nov 20.

Authors

Sascha G Keller¹, Andrea Pannwitz², Hendrik Mallin¹, Oliver S Wenger², Thomas R Ward¹

Affiliations

¹ Department of Chemistry, University of Basel, Mattenstrasse 24a, CH-4002, Basel, Switzerland.
² Department of Chemistry, University of Basel, St. Johanns-Ring 19, CH-4056, Basel, Switzerland.

PMID: 29024136
DOI: 10.1002/chem.201703885

Abstract

Long-lived photo-driven charge separation is demonstrated by assembling a triad on a protein scaffold. For this purpose, a biotinylated triarylamine was added to a Ru^II -streptavidin conjugate bearing a methyl viologen electron acceptor covalently linked to the N-terminus of streptavidin. To improve the rate and lifetime of the electron transfer, a negative patch consisting of up to three additional negatively charged amino acids was engineered through mutagenesis close to the biotin-binding pocket of streptavidin. Time-resolved laser spectroscopy revealed that the covalent attachment and the negative patch were beneficial for charge separation within the streptavidin hosted triad; the charge separated state was generated within the duration of the excitation laser pulse, and lifetimes up to 3120 ns could be achieved with the optimized supramolecular triad.

Keywords: charge separation; photosensitizer; streptavidin; triad; triarylamine.