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Selenomethionine as an Expressible Handle for Bioconjugations

preprint
revised on 20.04.2020 and posted on 21.04.2020 by Dillon T. Flood, Jordi C.J. Hintzen, Chenxi Lu, Philip A. Cistrone, Jason Chen, Takanori Otomo, Philip Dawson
Site-selective chemical protein ligation reactions are enabling tools for chemical biology. Herein, we employ a physical organic study to refine the selenomethionine (SeM) benzylation as a practical protein bioconjugation strategy. SeM is readily introduced through auxotrophic expression and exhibits unique nucleophilic properties that allow it to be selectively modified even in the presence of cysteine. The resulting benzylselenonium adduct is stable at physiological pH, selectively labile to glutathione and embodies a broadly tuneable reactivity profile. Guided by a mechanistic analysis of the reaction, a 4-bromomethylphenylacetyl linker is identified for efficient conjugations of complex organic molecules to SeM containing proteins. This optimized benzyl linker exhibits a rate constant of 3x10-1 M-1s-1, facilitating efficient conjugation at micromolar concentrations. The selenonium conjugate is further advanced through a linker that can be selectively photo-locked or reductively cleaved on demand. This tool-kit of selenonium forming reagents have broad potential in the development of chemically enhanced proteins.

Funding

NRSA Training Core

National Center for Advancing Translational Sciences

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History

Email Address of Submitting Author

dawson@scripps.edu

Institution

The Scripps Research Institute

Country

United States

ORCID For Submitting Author

0000-0002-2538-603X

Declaration of Conflict of Interest

No Conflicts

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