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Langridge, J. I.

Publications and source records attributed to Langridge, J. I..

2 recordsLinked to original sources

Advances in the Design and Functionality of a Compact Multi-Reflecting Time-of-Flight Mass Spectrometer

AO_SCPLOWBSTRACTC_SCPLOWO_ST_ABSRationaleC_ST_ABSHigh-resolution mass spectrometry is routinely used for the analysis of complex samples in pharmaceutical, environmental, and omics related studies. Such applications demand instrumentation to be capable of combining sub-ppm mass accuracy, high resolving power, rapid full m/z range acquisition, over a wide dynamic range. MethodsAchieving the above requirements places constraints on analyzer design and performance. Multi-reflecting time-of-flight (MRT) based analyzers have previously been reported as a means of significantly extending the effective flight path in compact TOF designs. Here, further instrument and functionality advances in a compact MRT mass spectrometer design are described. ResultsThe impact of these enhancements was assessed for targeted and non-targeted omics applications, examining the impact of acquisition speed on resolving power, dynamic range including limits of quantitation, and quantitative precision. ConclusionThe results obtained characterize the performance of the enhanced design features of a compact MRT mass spectrometer. Operation at elevated acquisition rates up to 200 Hz was observed without loss in resolving power, isotopic ratio accuracy, or quantitative precision.

biochemistry↗

Ion Mobility Separation of Isomeric Acyl-lysine Marks in Peptides

Isomeric post-translational modifications (PTMs) on proteins challenge proteomic analyses due to their identical mass and fragmentation patterns. We evaluate high-resolution ion mobility spectrometry (IMS) for separating three naturally occurring acyl-lysine isomer pairs on histones: crotonyl/methacryl, butyryl/isobutyryl and L-/D-lactyl. These PTMs were chemically installed on lysine residues 9 and 18 (K9, K18) of synthetic histone H3 peptides (residues 3-15 and 3-25). Using trapped IMS (TIMS) we observe half-height separation of H3[3-15] peptides possessing crotonyl/methacryl and L/D-lactyl marks, and the lactyl isomers of H3[3-25] can be distinguished. In contrast, multi-pass cyclic IMS (cIM) achieves baseline or near-baseline resolution for every pair, except the longest butyryl/isobutyryl peptide isomers, despite their collision-cross-section differences of {approx}1%. We show that resolution increased with the square root of cIM pass number, allowing baseline separation within 300 ms. Beyond separation, structure-mobility relationships emerge: branched modifications (isobutyryl, methacryl) yield more compact gas-phase conformations than their linear analogs (butyryl, crotonyl). For the doubly crotonylated/methacrylated peptides studied, both PTM identity and site determine the mobility. These results demonstrate IMS as a sensitive method for elucidation of acyl-modified histone peptide fine structure by resolving isomeric PTM ambiguity. This addresses a persistent analytical bottleneck and should be included in routine proteomics MS-based workflows

biochemistry↗