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Updated: Jun 11, 2025

Synthesis of Protein Bioconjugates via Cysteine-maleimide Chemistry
Published on: July 20, 2016
Fast and Selective Cysteine Conjugation Using para-Quinone Methides
Ruimin Zhang1, Bo Li1, Liuli Dong1
1School of Pharmacy, China Pharmaceutical University, Nanjing 211198, P. R. China.
Abstract:
An efficient and selective method for cysteine conjugation utilizing para-quinone methides (p-QMs) was developed. p-QM labeling exhibits high specificity toward the cysteine residue, as evidenced by its reactivity with various amino acid derivatives, peptides, and proteins. Notably, the p-QM-cysteine reactions display robust kinetics with rate constants up to 1.67 × 104 M-1·s-1. Furthermore, p-QM conjugation enables us to attach a fluorescent probe to a HER2 nanobody, resulting in selective labeling of HER2-positive SK-BR-3 cells.
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