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Context‐Dependence of the Reactivity of Cysteine and Lysine Residues

The S‐alkylation of Cys residues with a maleimide and the N (ϵ)‐acylation of Lys residues with an N‐hydroxysuccinimide (NHS) ester are common methods for bioconjugation. Using Cys and Lys derivatives as proxies, we assessed differences in reactivity depending on the position of Cys or Lys in a prote...

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Autores principales: Boll, Linus B., Raines, Ronald T.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9308718/
https://www.ncbi.nlm.nih.gov/pubmed/35527228
http://dx.doi.org/10.1002/cbic.202200258
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author Boll, Linus B.
Raines, Ronald T.
author_facet Boll, Linus B.
Raines, Ronald T.
author_sort Boll, Linus B.
collection PubMed
description The S‐alkylation of Cys residues with a maleimide and the N (ϵ)‐acylation of Lys residues with an N‐hydroxysuccinimide (NHS) ester are common methods for bioconjugation. Using Cys and Lys derivatives as proxies, we assessed differences in reactivity depending on the position of Cys or Lys in a protein sequence. We find that Cys position is exploitable to improve site‐selectivity in maleimide‐based modifications. Reactivity decreases substantially in the order N‐terminal>in‐chain>C‐terminal Cys due to modulation of sulfhydryl pK (a) by the α‐ammonium and carboxylate groups at the termini. A lower pK (a) value yields a larger fraction thiolate, which promotes selectivity while somewhat decreasing thiolate nucleophilicity in accord with [Formula: see text] =0.41. Lowering pH and salt concentration enhances selectivity still further. In contrast, differences in the reactivity of Lys towards an NHS ester were modest due to an appreciable decrease in amino group nucleophilicity with a lower pK (a) of its conjugate acid. Hence, site‐selective Lys modification protocols will require electrophiles other than NHS esters.
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spelling pubmed-93087182022-07-24 Context‐Dependence of the Reactivity of Cysteine and Lysine Residues Boll, Linus B. Raines, Ronald T. Chembiochem Research Articles The S‐alkylation of Cys residues with a maleimide and the N (ϵ)‐acylation of Lys residues with an N‐hydroxysuccinimide (NHS) ester are common methods for bioconjugation. Using Cys and Lys derivatives as proxies, we assessed differences in reactivity depending on the position of Cys or Lys in a protein sequence. We find that Cys position is exploitable to improve site‐selectivity in maleimide‐based modifications. Reactivity decreases substantially in the order N‐terminal>in‐chain>C‐terminal Cys due to modulation of sulfhydryl pK (a) by the α‐ammonium and carboxylate groups at the termini. A lower pK (a) value yields a larger fraction thiolate, which promotes selectivity while somewhat decreasing thiolate nucleophilicity in accord with [Formula: see text] =0.41. Lowering pH and salt concentration enhances selectivity still further. In contrast, differences in the reactivity of Lys towards an NHS ester were modest due to an appreciable decrease in amino group nucleophilicity with a lower pK (a) of its conjugate acid. Hence, site‐selective Lys modification protocols will require electrophiles other than NHS esters. John Wiley and Sons Inc. 2022-06-01 2022-07-19 /pmc/articles/PMC9308718/ /pubmed/35527228 http://dx.doi.org/10.1002/cbic.202200258 Text en © 2022 The Authors. ChemBioChem published by Wiley-VCH GmbH https://creativecommons.org/licenses/by-nc-nd/4.0/This is an open access article under the terms of the http://creativecommons.org/licenses/by-nc-nd/4.0/ (https://creativecommons.org/licenses/by-nc-nd/4.0/) License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non‐commercial and no modifications or adaptations are made.
spellingShingle Research Articles
Boll, Linus B.
Raines, Ronald T.
Context‐Dependence of the Reactivity of Cysteine and Lysine Residues
title Context‐Dependence of the Reactivity of Cysteine and Lysine Residues
title_full Context‐Dependence of the Reactivity of Cysteine and Lysine Residues
title_fullStr Context‐Dependence of the Reactivity of Cysteine and Lysine Residues
title_full_unstemmed Context‐Dependence of the Reactivity of Cysteine and Lysine Residues
title_short Context‐Dependence of the Reactivity of Cysteine and Lysine Residues
title_sort context‐dependence of the reactivity of cysteine and lysine residues
topic Research Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9308718/
https://www.ncbi.nlm.nih.gov/pubmed/35527228
http://dx.doi.org/10.1002/cbic.202200258
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