Dual Nano-Electrospray for Probing Solution Interactions and Fast Reactions of Complex Biomolecules

A novel nano-electrospray emitter has been developed containing two separated channels running throughout the length of the emitter. The emitters have been fabricated from "theta-shaped" borosilicate capillaries. Loading of different solutions into the two different channels opens up the possibility to study short timescale interactions within a Taylor cone common to both channels. The common Taylor cone constitutes an extremely small "mixing volume" of the order of femtolitres. The products of electrospray from the dual-channel emitters have been analysed by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. Results are presented for interactions of vancomycin with diacetyl-L-lysyl-D-alanyl- D-alanine and interactions of vancomycin with deuterated vancomycin. On the basis of these results, it is concluded that, during electrospray, specific non-covalent adducts have been formed and that there have been exchange reactions involving making and breaking of covalent bonds.