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Full-Text Articles in Physical Sciences and Mathematics
Identification Of Phospholipids In Human Meibum By Nano-Electrospray Ionisation Tandem Mass Spectrometry, Jennifer T. Saville, Zhenjun Zhao, Mark Dp Willcox, Manjula A. Ariyavidana, Stephen J. Blanksby, Todd W. Mitchell
Identification Of Phospholipids In Human Meibum By Nano-Electrospray Ionisation Tandem Mass Spectrometry, Jennifer T. Saville, Zhenjun Zhao, Mark Dp Willcox, Manjula A. Ariyavidana, Stephen J. Blanksby, Todd W. Mitchell
Stephen Blanksby
Meibum is believed to be the major source of tear !lm lipids, which are vital in the prevention of excessevaporation of the aqueous phase. The complete lipid composition of meibum has yet to be established.While earlier studies reported the presence of phospholipids in human meibum, recent mass spectrometricstudies have not detected them. In this study we use electrospray ionisation tandem massspectrometry to investigate the presence of phospholipids in meibum and provide comparison to thephospholipid pro!le of tears.Lipids were extracted from human meibum and tear samples using standard biphasic methods andanalysed by nano-electrospray ionisation tandem mass spectrometry using targeted ion scans. …
Ozone Induced Dissociation: Elucidation Of Double Bond Position Within Mass-Selected Lipid Ions, Michael C. Thomas, Todd W. Mitchell, David G. Harman, Jane M. Deeley, Jessica R. Nealon, Stephen J. Blanksby
Ozone Induced Dissociation: Elucidation Of Double Bond Position Within Mass-Selected Lipid Ions, Michael C. Thomas, Todd W. Mitchell, David G. Harman, Jane M. Deeley, Jessica R. Nealon, Stephen J. Blanksby
Stephen Blanksby
Ions formed from lipids during electrospray ionization of crude lipid extracts have been mass-selected within a quadrupole linear ion trap mass spectrometer and allowed to react with ozone vapor. Gas-phase ion−molecule reactions between unsaturated lipid ions and ozone are found to yield two primary product ions for each carbon−carbon double bond within the molecule. The mass-to-charge ratios of these chemically induced fragments are diagnostic of the position of unsaturation within the precursor ion. This novel analytical technique, dubbed ozone-induced dissociation (OzID), can be applied both in series and in parallel with conventional collision-induced dissociation (CID) to provide near-complete structural assignment …
Identification Of Abundant Alkyl Ether Glycerophospholipids In The Human Lens By Tandem Mass Spectrometry Techniques, Roger J. Truscott, Jane Deeley, Todd W. Mitchell, Michael Thomas, Stephen J. Blanksby
Identification Of Abundant Alkyl Ether Glycerophospholipids In The Human Lens By Tandem Mass Spectrometry Techniques, Roger J. Truscott, Jane Deeley, Todd W. Mitchell, Michael Thomas, Stephen J. Blanksby
Stephen Blanksby
Previous studies have shown that the human lens contains glycerophospholipids with ether linkages. These lipids differ from conventional glycerophospholipids in that the sn-1 substituent is attached to the glycerol backbone via an 1-O-alkyl or an 1-O-alk-1'-enyl ether rather than an ester bond. The present investigation employed a combination of collision-induced dissociation (CID) and ozone-induced dissociation (OzID) to unambiguously distinguish such 1-O-alkyl and 1-O-alk-1'-enyl ethers. Using these methodologies the human lens was found to contain several abundant 1-O-alkyl glycerophos-phoethanolamines, including GPEtn(16:0e/9Z-18:1), GPEtn(11Z-18:1e/9Z-18:1), and GPEtn(18:0e/9Z-18:1), as well as a related series of unusual 1-O-alkyl glycerophosphoserines, including GPSer(16:0e/9Z-18:1), GPSer(11Z-18:1e/9Z-18:1), GPSer(18:0e/9Z-18:1) that to our …
Detection And Quantification Of Tear Phospholipids And Cholesterol In Contact Lens Deposits: The Effect Of Contact Lens Material And Lens Care Solution, Jennifer Saville, Zhenjun Zhao, Mark D.P. Willcox, Stephen J. Blanksby, Todd W. Mitchell
Detection And Quantification Of Tear Phospholipids And Cholesterol In Contact Lens Deposits: The Effect Of Contact Lens Material And Lens Care Solution, Jennifer Saville, Zhenjun Zhao, Mark D.P. Willcox, Stephen J. Blanksby, Todd W. Mitchell
Stephen Blanksby
PURPOSE. To examine the deposition of tear phospholipids and cholesterol onto worn contact lenses and the effect of lens material and lens care solution. METHODS. Lipids were extracted from tears and worn contact lenses using 2: 1 chloroform: methanol and the extract washed with aqueous ammonium acetate, before analysis by electrospray ionization tandem mass spectrometry (ESI-MS/MS). RESULTS. Twenty-three molecular lipids from the sphingomyelin (SM) and phosphatidylcholine (PC) classes were detected in tears, with total concentrations of each class determined to be 5 +/- 1 pmol/mu L (similar to 3.8 mu g/mL) and 6 +/- 1 pmol/mu L (similar to 4.6 …
Online Ozonolysis Methods For The Determination Of Double Bond Position In Unsaturated Lipids, Michael Thomas, Todd W. Mitchell, Stephen J. Blanksby
Online Ozonolysis Methods For The Determination Of Double Bond Position In Unsaturated Lipids, Michael Thomas, Todd W. Mitchell, Stephen J. Blanksby
Stephen Blanksby
Modern lipidomics relies heavily on mass spectrometry for the structural characterization and quantification of lipids of biological origins. Structural information is gained by tandem mass spectrometry (MS/MS) whereby lipid ions are fragmented to elucidate lipid class, fatty acid chain length, and degree of unsaturation. Unfortunately, however, in most cases double bond position cannot be assigned based on MS/MS data alone and thus significant structural diversity is hidden from such analyses. For this reason, we have developed two online methods for determining double bond position within unsaturated lipids; ozone electrospray ionization mass spectrometry (OzESI-MS) and ozone-induced dissociation (OzID). Both techniques utilize …
Identification Of Abundant Alkyl Ether Glycerophospholipids In The Human Lens By Tandem Mass Spectrometry Techniques, Roger J. Truscott, Jane Deeley, Todd W. Mitchell, Michael Thomas, Stephen J. Blanksby
Identification Of Abundant Alkyl Ether Glycerophospholipids In The Human Lens By Tandem Mass Spectrometry Techniques, Roger J. Truscott, Jane Deeley, Todd W. Mitchell, Michael Thomas, Stephen J. Blanksby
Stephen Blanksby
Previous studies have shown that the human lens contains glycerophospholipids with ether linkages. These lipids differ from conventional glycerophospholipids in that the sn-1 substituent is attached to the glycerol backbone via an 1-O-alkyl or an 1-O-alk-1'-enyl ether rather than an ester bond. The present investigation employed a combination of collision-induced dissociation (CID) and ozone-induced dissociation (OzID) to unambiguously distinguish such 1-O-alkyl and 1-O-alk-1'-enyl ethers. Using these methodologies the human lens was found to contain several abundant 1-O-alkyl glycerophos-phoethanolamines, including GPEtn(16:0e/9Z-18:1), GPEtn(11Z-18:1e/9Z-18:1), and GPEtn(18:0e/9Z-18:1), as well as a related series of unusual 1-O-alkyl glycerophosphoserines, including GPSer(16:0e/9Z-18:1), GPSer(11Z-18:1e/9Z-18:1), GPSer(18:0e/9Z-18:1) that to our …
Tandem Mass Spectrometry Of Deprotonated Iodothyronines, A. M. Couldwell, M. C. Thomas, Todd Mitchell, A. Hulbert, Stephen J. Blanksby
Tandem Mass Spectrometry Of Deprotonated Iodothyronines, A. M. Couldwell, M. C. Thomas, Todd Mitchell, A. Hulbert, Stephen J. Blanksby
Stephen Blanksby
In order to assist with the development of more selective and sensitive methods for thyroid hormone analysis the [M-H]– anions of the iodothyronines; T4, T3, rT3, (3,5)-T2 and the non-iodinated thyronine (T0) have been generated by negative ion electrospray mass spectrometry. Tandem mass spectra of these ions were recorded on a triple quadrupole mass spectrometer and show a strong analogy with the fragmentation pathways of the parent compound, tyrosine. All iodothyronines also show significant abundances of the iodide anion in their tandem mass spectra, which represents an attractive target for MRM analysis, given that iodothyronines are the only iodine bearing …
A Comparison Of The Gas Phase Acidities Of Phospholipid Headgroups:Experimental And Computational Studies, M. C. Thomas, Todd Mitchell, Stephen J. Blanksby
A Comparison Of The Gas Phase Acidities Of Phospholipid Headgroups:Experimental And Computational Studies, M. C. Thomas, Todd Mitchell, Stephen J. Blanksby
Stephen Blanksby
Proton-bound dimers consisting of two glycerophospholipids with different headgroups were prepared using negative ion electrospray ionization and dissociated in a triple quadrupole mass spectrometer. Analysis of the tandem mass spectra of the dimers using the kinetic method provides, for the first time, an order of acidity for the phospholipid classes in the gas phase of PE < PA << PG < PS < PI. Hybrid density functional calculations on model phospholipids were used to predict the absolute deprotonation enthalpies of the phospholipid classes from isodesmic proton transfer reactions with phosphoric acid. The computational data largely support the experimental acidity trend, with the exception of …