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

Characterization of Protein Structure with Ion Mobility Mass Spectrometry, Multiplexed Fragmentation Strategies and Data Directed Analysis

Activated ion mobility measurements provide Insights to the stability of tertiary and quaternary structures of proteins and pairing such approaches with fragmentation can delineate which part(s) of the primary sequence are disrupted from a folded structure. In this work we use 213 nm photodissociation coupled with ion mobility mass spectrometry and collisional activation to determine the conformational landscape of model proteins. UVPD experiments are performed on proteins following in source activation as well as on collisionally activated photoproducts post ion mobility separation. For cytochrome c, there is a significant increase in the fragmentation yield with collisional activation post mobility, for all conformational states. Similar strategies are deployed with the model multimeric proteins, concanavalin a, and haemoglobin. For these complexes’ CID leads to classic asymmetric charge distribution in subunit products, which when preceded by UV irradiation yields fragments from within the sub-unit that can be mapped to the quaternary fold. Data driven, multivariate analysis (MVA) was used to determine the significant differences in UVPD and CID fragmentation pattern following in source activation. This data driven approach reveals diagnostic fragments without a priori assignments limited to predicated backbone cleavage and provides a new approach to map conformation landscapes that may have wider utility.</p

Galactose Oxidase Enables Modular Assembly of Conjugates from Native Antibodies with High Drug-to-Antibody Ratios**

The potential of antibody conjugates with high drug loading in anticancer therapy has recently been highlighted by the approval of Trastuzumab deruxtecan and Sacituzumab govitecan. These biopharmaceutical approaches have spurred interest in bioconjugation strategies with high and defined degrees of drug‐to‐antibody ratio (DAR), in particular on native antibodies. Here, a glycoengineering methodology was developed to generate antibody drug conjugates with DAR of up to eight, by combining highly selective enzymatic galactosylation and oxidation with biorthogonal tandem Knoevenagel–Michael addition chemistry. This four‐step approach offers a selective route to conjugates from native antibodies with high drug loading, and thus illustrates how biocatalysis can be used for the generation of biopharmaceuticals using mild reaction conditions

Galactose Oxidase Enables Modular Assembly of Conjugates from Native Antibodies with High Drug-to-Antibody Ratios

The potential of antibody conjugates with high drug loading in anticancer therapy has recently been highlighted by the approval of Trastuzumab deruxtecan and Sacituzumab govitecan. These biopharmaceutical approaches have spurred interest in bioconjugation strategies with high and defined degrees antibody-to-drug (DAR) ratios, in particular on native antibodies. Here we report a glycoengineering methodology to generate antibody drug conjugates with DAR of up to eight, by combining highly selective enzymatic galactosylation and oxidation with biorthogonal tandem Knoevenagel-Michael addition chemistry. This three step approach offers a selective route to conjugates from native antibodies with high drug loading, and thus illustrates how biocatalysis can be used for the generation of biopharmaceuticals using mild reaction conditions