Native Taylor/Non-Taylor Dispersion – Mass Spectrometry (TNT-MS) Allows Rapid Protein Desalting and Multiplexed, Label-Free Ligand Screening

ABSTRACT: Native mass spectrometry (MS) has become an important technique in several fields including structural biology and drug discovery, due to its ability to study non-covalent assemblies in the gas phase. In many settings, the main drawbacks of native MS are the incompatibility of electrospray ionisation with non-volatile salts and the risk of protein signal suppression if small, efficiently ionising molecules are present in the sample. This often requires an offline buffer exchange step and/or parallel sample preparation workflow to other analytical methods, reducing both the adoption and the throughput of native MS. Here, we exploit the dynamics of analytes flowing through an open tubular capillary to keep molecules with a small hydrodynamic radius (e.g., salts) inside a Taylor dispersion regime, while pushing larger species (e.g., proteins) into a non-Taylor regime. The result of this is that the larger species elute earlier, and are effectively buffer exchanged within the capillary on a timescale of approximately 30 seconds. In addition to desalting of proteins injected in solutions containing 25 to 200 mM NaCl and other biologically relevant buffers (e.g., HEPES, TCEP, and glycerol), we also demonstrate that this method can separate unbound small molecules from protein-ligand complexes, enabling rapid, multiplexed ligand screening based on native MS. Finally, we investigated the dependence of the critical flow rate required to push proteins outside the Taylor regime on protein size, enabling limited size-based separation of proteins and providing a starting point for others to adopt this method. Taylor/non-Taylor dispersion mass spectrometry (TNT-MS) was implemented using an unmodified LC-MS system operated without a chromatographic column and coupled to an autosampler. This allows significant automation, which we believe will contribute to the wider adoption of native MS as a routine method.

INSTRUMENT(S): Synapt MS

ORGANISM(S): Bos Taurus (bovine) Homo Sapiens (human) Mus Musculus (mouse)

SUBMITTER: Jonathan Eisert  

LAB HEAD: Prof. Frederik Lermyte

PROVIDER: PXD063440 | Pride | 2025-07-10

REPOSITORIES: Pride