These are preliminary reports that have not been peer-reviewed. They should not be regarded as conclusive, guide clinical practice/health-related behavior, or be reported in news media as established information. For more information, please see our FAQs.
Preprints are manuscripts made publicly available before they have been submitted for formal peer review and publication. They might contain new research findings or data. Preprints can be a draft or final version of an author's research but must not have been accepted for publication at the time of submission.
revised on 20.04.2020 and posted on 21.04.2020by 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.