Partial covariance two-dimensional mass spectrometry for determination of biomolecular primary structure

TL;DR

This paper introduces partial covariance two-dimensional mass spectrometry (pC-2DMS), a novel technique that improves the accuracy of biomolecular primary structure determination by analyzing fragment correlations, surpassing traditional one-dimensional MS limitations.

Contribution

The paper presents a new 2D MS method based on partial covariance mapping that enhances structural analysis of biomolecules by detecting fragment correlations, providing more specific sequence and modification information.

Findings

pC-2DMS reveals fragment correlations for better structural insights

It distinguishes isomeric histone peptides unresolvable by standard MS

Provides higher fidelity in primary structure determination

Abstract

Mass spectrometry (MS) is used widely in biomolecular structural analysis and is particularly dominant in the study of proteins. Despite its considerable power, state-of-the-art protein MS frequently suffers from limited reliability of spectrum-to-structure assignments. This could not be solved fully by the dramatic increase in mass accuracy and resolution of modern MS instrumentation or by the introduction of new fragmentation methods. Here we present a new kind of two-dimensional mass spectrometry for high fidelity determination of a biomolecular primary structure based on partial covariance mapping. Partial covariance two-dimensional mass spectrometry (pC-2DMS) detects intrinsic statistical correlations between biomolecular fragments originating from the same or consecutive decomposition events. This enables identification of pairs of ions produced along the same fragmentation pathway of a biomolecule across its entire fragment mass spectrum. We demonstrate that the fragment-fragment correlations revealed by pC-2DMS provide much more specific information on the amino acid sequence and its covalent modifications than the individual fragment mass-to-charge ratios on which standard one-dimensional MS is based. We illustrate the power of pC-2DMS by using it to resolve structural isomers of combinatorially modified histone peptides inaccessible to standard MS.