High-energy collision-induced dissociation by MALDI TOF/TOF causes charge-remote fragmentation of steroid sulfates.
A method for structural elucidation of biomolecules dating to the 1980s utilized high-energy collisions (~10 keV, laboratory frame) that induced charge-remote fragmentations (CRF), a class of fragmentations particularly informative for lipids, steroids, surfactants, and peptides. Unfortunately, the capability for high-energy activation has largely disappeared with the demise of magnetic sector instruments. With the latest designs of tandem time-of-flight mass spectrometers (TOF/TOF), however, this capability is now being restored to coincide with the renewed interest in metabolites and lipids, including steroid-sulfates and other steroid metabolites. For these metabolites, structure determinations are required at concentration levels below that appropriate for NMR. To meet this need, we explored CRF with TOF/TOF mass spectrometry for two groups of steroid sulfates, 3-sulfates and 21-sulfates. We demonstrated that the current generation of MALDI TOF/TOF instruments can generate charge-remote fragmentations for these materials. The resulting collision-induced dissociation (CID) spectra are useful for positional isomer differentiation and very often allow the complete structure determination of the steroid. We also propose a new nomenclature that directly indicates the cleavage sites on the steroid ring with carbon numbers.
Department of Chemistry, Washington University in St. Louis, St. Louis, MO, 63130, USA.
Yuetian
Y
Yan
Masaaki
M
Ubukata
Robert B
RB
Cody
Timothy E
TE
Holy
Michael L
ML
Gross
D002788:Cholesterol Esters / Q000032:analysis / Q000737:chemistry; D055664:Electrochemical Techniques; D004735:Energy Transfer; D007536:Isomerism; D057230:Limit of Detection; D008832:Microchemistry / Q000379:methods; D008958:Models, Molecular; D015394:Molecular Structure; D008970:Molecular Weight; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013256:Steroids / Q000032:analysis* / Q000737:chemistry; D013431:Sulfates / Q000032:analysis* / Q000737:chemistry; D053719:Tandem Mass Spectrometry; D009626:Terminology as Topic
D002788:Cholesterol Esters; D013256:Steroids; D013431:Sulfates; C007045:cholesteryl sulfate