Horner-Wadsworth-Emmons Olefination of Proteins and Glycoproteins

Chemo-selective and site-specific modifications of proteins are fundamental to the advancement of biological and pharmaceutical sciences, from understanding the basis of cellular biology to development of biotherapeutics. Recent successes in bioconjugation chemistry have inspired the search for more biocompatible chemical reactions, which has prompted us to investigate Horner-Wadsworth-Emmons (HWE) olefinations, iconic reactions used widely in organic synthesis that would give rise to new selective protein olefinations. Our choice of HWE olefinations was inspired by the growing number of methods for the generation of aldehydes as transient reactive groups in proteins and the potential for mild and simple reaction conditions. Here we show that HWE on aldehydes produced by both chemical and enzymatic methods is fully compatible with physiological conditions and highly selective in small and large proteins, including therapeutic antibodies. By exploiting the wide range of easily accessible HWE reagents provided by organic chemistry, we show that the reaction kinetics can be fine-tuned over orders of magnitude by judicious use of substituents. The electrophilic nature of the HWE products can be tuned to allow for subsequent nucleophilic additions, including thiol- and phospha-Michael additions, enabling two-step dual labelling strategies. Our results demonstrate that HWE olefination of aldehydes in proteins provide efficient and selective bioconjugation chemistries that are orthogonal to existing methods.