A New Chemical tool for Protein Modifications: Bioorthogonal Staudinger-Phosphite and Phosphonite Reactions
In the course of the investigation of a Lewis-acid catalyzed phosphorimidate-phosphoramidate rearrangement, we discovered a quantitative hydrolysis of the phosphorimidate intermediates upon the addition of water. Building upon this observation, we used the Staudinger-phosphite reaction to convert azides into phosphoramidates either in solution or on the solid support. In a first biological application of this reaction we developed a chemoselective phosphorylation of proteins, which allowed in combination with unnatural protein translation a site-specific incorporation of a charged phosphoramidate moiety into a protein (Scheme 1), which is recognized by a phospho-Tyr specific antibody. In subsequent studies, we engineered an unsymmetrical version of the Staudinger-phosphite as well as a Staudinger-phosphonite reaction for the chemical lipidation, biotinylation and glycosylation of proteins as well as polymeric materials.
Finally, we demonstrated that the Staudinger-phosphite is an efficient transformation even in a highly crowded bio-environment, such as E.coli lysate. Consequently, we further employed this reaction for an efficient and metal-free PEGylation of a model azido-phenylalanine containing protein, which delivers a new class of branched oligoethylene glycol scaffolds for the stabilization of biopolymers in lysates and in the cytosol.
(Reference: R. Serwa, I. Wilkening, G. del Signore, M. Mühlberg, I. Claußnitzer, C. Weise, M. Gerrits, C. P. R. Hackenberger*
Angew. Chem. 2009, 121, 8382-8387 Angew. Chem. Int. Ed. 2009, 47, 8234-8239
Chemoselective Staudinger-Phoshpite Reaction of Azides for the Phosphorylation of Proteins)