Native Mass Spectrometry: What is in the Name?

TLDR

Electrospray ionization mass spectrometry has become a cornerstone of proteomics, and recent advances now allow analysis of noncovalent protein, DNA, and RNA–protein complexes while preserving their native quaternary structure, a capability that has matured over two decades to elucidate structure–function relationships. This perspective aims to trace the origins of and redefine the term native MS, clarifying its intended meaning and scope. The authors provide a detailed historical account of the term’s coinage and explicitly delineate what native MS does not encompass. Illustrative examples demonstrate native MS’s successes to date and its broad utility for addressing complex biological questions.

Abstract

Electrospray ionization mass spectrometry (ESI-MS) is nowadays one of the cornerstones of biomolecular mass spectrometry and proteomics. Advances in sample preparation and mass analyzers have enabled researchers to extract much more information from biological samples than just the molecular weight. In particular, relevant for structural biology, noncovalent protein–protein and protein–ligand complexes can now also be analyzed by MS. For these types of analyses, assemblies need to be retained in their native quaternary state in the gas phase. This initial small niche of biomolecular mass spectrometry, nowadays often referred to as "native MS," has come to maturation over the last two decades, with dozens of laboratories using it to study mostly protein assemblies, but also DNA and RNA-protein assemblies, with the goal to define structure–function relationships. In this perspective, we describe the origins of and (re)define the term native MS, portraying in detail what we meant by "native MS," when the term was coined and also describing what it does (according to us) not entail. Additionally, we describe a few examples highlighting what native MS is, showing its successes to date while illustrating the wide scope this technology has in solving complex biological questions.