Abstract
Through mechanistic work and rational design, we have developed the fastest abiotic Cys bioconjugation. As a result, the developed organometallic Au(III) bioconjugation reagents enable selective labelling of Cys moieties down to pM concentrations and allow for the rapid construction of complex heterostructures from peptides, proteins, and oligonucleotides. This work showcases how organometallic chemistry can be interfaced with biomolecules and lead to the range of reactivities that are unmatched by classical organic chemistry tools.