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Post-translational site-selective protein backbone α-deuteration

2018; Nature Portfolio; Volume: 14; Issue: 10 Linguagem: Inglês

10.1038/s41589-018-0128-y

1552-4469

Sébastien R. G. Galan, James R. Wickens, Jitka Daďová, Wai‐Lung Ng, Xinglong Zhang, Robert Simion, Robert Quinlan, Elisabete Pires, Robert S. Paton, Stephen Caddick, Vijay Chudasama, Benjamin G. Davis,

Chemical Synthesis and Analysis

Isotopic replacement has long-proven applications in small molecules. However, applications in proteins are largely limited to biosynthetic strategies or exchangeable (for example, N-H/D) labile sites only. The development of postbiosynthetic, C-1H → C-2H/D replacement in proteins could enable probing of mechanisms, among other uses. Here we describe a chemical method for selective protein α-carbon deuteration (proceeding from Cys to dehydroalanine (Dha) to deutero-Cys) allowing overall 1H→2H/D exchange at a nonexchangeable backbone site. It is used here to probe mechanisms of reactions used in protein bioconjugation. This analysis suggests, together with quantum mechanical calculations, stepwise deprotonations via on-protein carbanions and unexpected sulfonium ylides in the conversion of Cys to Dha, consistent with a 'carba-Swern' mechanism. The ready application on existing, intact protein constructs (without specialized culture or genetic methods) suggests this C-D labeling strategy as a possible tool in protein mechanism, structure, biotechnology and medicine.