Carbohydrates and their derivatives play important roles in biological systems, but their isomeric heterogeneity also presents a considerable challenge for analytical techniques. Here, a stepwise approach using infrared multiple-photon dissociation (IRMPD) via a tunable CO2 laser (9.2-10.7 μm) was employed to characterize isomeric variants of glucose-based trisaccharides. After the deprotonated trisaccharides were trapped and fragmented to disaccharide C2 fragments in a Fourier transform ion cyclotron resonance (FTICR) cell, a further variable-wavelength infrared irradiation of the C2 ion produced wavelength-dependent dissociation patterns that are represented as heat maps. The photodissociation patterns of these C2 fragments are shown to be strikingly similar to the photodissociation patterns of disaccharides with identical glycosidic bonds. Conversely, the photodissociation patterns of different glycosidic linkages exhibit considerable differences. On the basis of these results, the linkage position and anomericity of glycosidic bonds of disaccharide units in trisaccharides can be systematically differentiated and identified, providing a promising approach to characterize the structures of isomeric oligosaccharides.
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http://dx.doi.org/10.1007/s13361-014-1025-6 | DOI Listing |
J Chem Phys
December 2024
Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, Serrano 123, 28006 Madrid, Spain.
Photodissociation of the CH2Cl radical is investigated by using high-level multireference configuration interaction ab initio methods, including the spin-orbit coupling. All possible fragmentation pathways, namely, CH2Cl + hν → CH2 + Cl, HCCl + H, and CCl + H2, have been analyzed. The potential-energy curves of the ground and several excited electronic states along the corresponding dissociating bond distance of each pathway have been calculated.
View Article and Find Full Text PDFACS Phys Chem Au
November 2024
Department of Chemistry, University of Washington, Seattle, Washington 98195, United States.
Using trianisole heptazine (TAHz) as a monomeric analogue for carbon nitride, we performed ultrafast pump-photolysis-probe transient absorption (TA) spectroscopy on the intermediate TAHzH heptazinyl radical produced from an excited state PCET reaction with 4-methoxyphenol (MeOPhOH). Our results demonstrate an optically gated photolysis that releases H and regenerates ground state TAHz. The TAHzH radical signature at 520 nm had a lifetime of 7.
View Article and Find Full Text PDFAnal Chem
December 2024
Department of Chemistry, University of Texas, Austin, Texas 78712, United States.
J Mater Chem B
November 2024
Department of Technology for Organic Synthesis, Ural Federal University, 19 Mira Str., Yekaterinburg, 620002, Russia.
A series of fluorophores based on the (5-methyl-4-phenylthiazol-2-yl)-3-phenylacrylonitrile (MPTA) core were designed and synthesised for photocaging of amino acids and peptides. The photophysical characteristics of these compounds and their hybrids with biomolecules were thoroughly investigated through a joint experimental, spectral and computational approach. The photorelease ability of the obtained amino acids-MPTA and peptides-MPTA hybrids was studied under various conditions, including different UV irradiation wavelength and power, and solvents.
View Article and Find Full Text PDFAnal Chem
October 2024
Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States.
Ultraviolet photodissociation (UVPD) has been shown to be a versatile ion activation strategy for the characterization of peptides and intact proteins among other classes of biological molecules. Combining the high-performance mass spectrometry (MS/MS) capabilities of UVPD with the high-resolution separation of trapped ion mobility spectrometry (TIMS) presents an opportunity for enhanced structural elucidation of biological molecules. In the present work, we integrate a 193 nm excimer laser in a TIMS-time-of-flight (TIMS-TOF) mass spectrometer for UVPD in the collision cell and use it for the analysis of several mass-mobility-selected species of ubiquitin and myoglobin.
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