scholarly journals Ion mobility mass spectrometry of peptide, protein, and protein complex ions using a radio-frequency confining drift cell

The Analyst ◽  
2016 ◽  
Vol 141 (3) ◽  
pp. 884-891 ◽  
Author(s):  
Samuel J. Allen ◽  
Kevin Giles ◽  
Tony Gilbert ◽  
Matthew F. Bush

A new drift cell was used to measure collision cross sections and characterize the origins of ion mobility peak broadening for biological molecules and assemblies.

2021 ◽  
Vol 12 ◽  
Author(s):  
Kai P. Law ◽  
Wei He ◽  
Jianchang Tao ◽  
Chuanlun Zhang

Archaea are differentiated from the other two domains of life by their biomolecular characteristics. One such characteristic is the unique structure and composition of their lipids. Characterization of the whole set of lipids in a biological system (the lipidome) remains technologically challenging. This is because the lipidome is innately complex, and not all lipid species are extractable, separable, or ionizable by a single analytical method. Furthermore, lipids are structurally and chemically diverse. Many lipids are isobaric or isomeric and often indistinguishable by the measurement of mass or even their fragmentation spectra. Here we developed a novel analytical protocol based on liquid chromatography ion mobility mass spectrometry to enhance the coverage of the lipidome and characterize the conformations of archaeal lipids by their collision cross-sections (CCSs). The measurements of ion mobility revealed the gas-phase ion chemistry of representative archaeal lipids and provided further insights into their attributions to the adaptability of archaea to environmental stresses. A comprehensive characterization of the lipidome of mesophilic marine thaumarchaeon, Nitrosopumilus maritimus (strain SCM1) revealed potentially an unreported phosphate- and sulfate-containing lipid candidate by negative ionization analysis. It was the first time that experimentally derived CCS values of archaeal lipids were reported. Discrimination of crenarchaeol and its proposed stereoisomer was, however, not achieved with the resolving power of the SYNAPT G2 ion mobility system, and a high-resolution ion mobility system may be required for future work. Structural and spectral libraries of archaeal lipids were constructed in non-vendor-specific formats and are being made available to the community to promote research of Archaea by lipidomics.


The Analyst ◽  
2016 ◽  
Vol 141 (1) ◽  
pp. 70-75 ◽  
Author(s):  
Matteo T. Degiacomi ◽  
Justin L. P. Benesch

EM∩IM enables the calculation of collision cross-sections from electron density maps obtained, for example, by means of transmission electron microscopy. This capability will further aid the integration of ion mobility mass spectrometry with modern structural biology.


2014 ◽  
Vol 86 (21) ◽  
pp. 10789-10795 ◽  
Author(s):  
Johanna Hofmann ◽  
Weston B. Struwe ◽  
Charlotte A. Scarff ◽  
James H. Scrivens ◽  
David J. Harvey ◽  
...  

2012 ◽  
Vol 65 (5) ◽  
pp. 504 ◽  
Author(s):  
Antonio N. Calabrese ◽  
Lauren A. Speechley ◽  
Tara L. Pukala

This study demonstrates the ability of travelling wave ion mobility-mass spectrometry to measure collision cross-sections of ions in the negative mode, using a calibration based approach. Here, negative mode ion mobility-mass spectrometry was utilised to understand structural transitions of calmodulin upon Ca2+ binding and complexation with model peptides melittin and the plasma membrane Ca2+ pump C20W peptide. Coexisting calmodulin conformers were distinguished on the basis of their mass and cross-section, and identified as relatively folded and unfolded populations, with good agreement in collision cross-section to known calmodulin geometries. Titration of calcium tartrate to physiologically relevant Ca2+ levels provided evidence for intermediately metalated species during the transition from apo- to holo-calmodulin, with collision cross-section measurements indicating that higher Ca2+ occupancy is correlated with more compact structures. The binding of two representative peptides which exemplify canonical compact (melittin) and extended (C20W) peptide-calmodulin binding models has also been interrogated by ion mobility mass spectrometry. Peptide binding to calmodulin involves intermediates with metalation states from 1–4 Ca2+, which demonstrate relatively collapsed structures, suggesting neither the existence of holo-calmodulin or a pre-folded calmodulin conformation is a prerequisite for binding target peptides or proteins. The biological importance of the different metal unsaturated calmodulin complexes, if any, is yet to be understood.


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