Методом плазменно-десорбційної мас-спектрометрії з іонізацією уламками поділу С/-252 дослід жено взаємодію стероїдних глікозидів біозиду неотігогеніну та тріозиду неотігогеніну з низкою амінокислот. Встановлено, що ці речовини здатні вступати у взаємодію з деякими аміно кислотами з утворенням нековалентнозв'язаних асоціатів.
252Cf Plasma desorption with time-of-flight mass spectrometry (TOF-PDMS) has been applied to comparative studies of the interactions of steroid glycosides (SGs) of the spirostan series with amino acids. SGs can interact with amino acids to form heteroclusters of the type [SG + aminoacid + H](+) and [SG + aminoacid + K](+). It is shown how the affinity of SGs for amino acids depends on the structures of both the SG carbohydrate chain and the SG aglycone, and on the nature of the amino acid side chain. Copyright 2000 John Wiley & Sons, Ltd.
252 Cf plasma desorption mass spectrometry was used to investigate the formation of complexes of 7-amino-4-methylcoumarins with -and γ-cyclodextrins. The individual substances and their co-ground mixtures were analyzed by plasma desorption ionization. In the negative-ion mass spectra of cyclodextrins highly characteristic fragmentation peaks were detected, and a scheme for the fragmentation pathway is proposed. The inclusion complex of 7-amino-4-methylcoumarin with -cyclodextrin was obtained, and the peak corresponding to the complex was observed in the PDMS spectra. Various modes of inclusion of the coumarins into cyclodextrins, that can result in stable complex formation, are discussed in the light of molecular mechanics calculations. In spite of the possibility in principle of the inclusion of 7-amino-4-methylcoumarin into -cyclodextrin, and of 7-N,N-diethyl-amino-4-methylcoumarin into γ-cyclodextrin, the complexes of these compounds appear to be insufficiently stable and they decomposed under the desorption/ionization conditions.
The quantitative investigation of the four RNA nucleosides (adenosine, guanosine, cytidine and uridine) using fast-atom bombardment mass spectra is reported. Nucleoside concentrations are varied in the 0.8-4% range. The nucleoside hydrogen-bonded complexes are shown to form primarily on the liquid matrix surface.Fast-atom bombardment mass spectrometry (FAB-MS) is widely used in investigations of organic substances.' This technique is especially applicable to labile biological substances. FAB-MS also allows hydrogen-bonded complexes to be For example, Greco et a1.' measured the proton affinity of various nucleosides (Ns), utilizing FAB only as a source of specific ions, but the origin of complexes was not studied. Although accurate measurements of FAB mass spectra are quite their quantitative interpretation is still difficult due to complicated ion formation processes. The ion current can be influenced by a variety of substance properties, such as solubility, p~, , surface activity etc.6 Publications devoted to the elucidation of the ion formation mechanism are numerous, yet all the models described can be sorted into two groups: 'preformed ions' models and 'gas-phase reaction' models.In this paper we study the intensities of the main ion currents in the nucleoside FAB mass spectra as a function of the nucleoside concentration in the glycerol matrix and make an attempt to reveal some details of ion cluster formation. EXPERIMENTALAnalyses were performed with an MI-1201E mass spectrometer manufactured by SELMI (Sumy , Ukraine) and equipped with a FAB ion source. Samples were bombarded with a primary 5 keV argon atom beam. A copper strip served as a sample holder. Commercial nucleosides (Serva, Germany) were used in the experiments. Commercial synthetic glycerol (Gl) was dried in uacw before using it as a matrix. Dimethylsulfoxide (DMSO) was employed as solvent for all the nucleosides. Weights of all the components were measured with an accuracy of 0.05 mg. Approximately 10 mg of the nucleoside was dissolved in 0.06 mL of DMSO and then mixed with 0.1 mL of dried glycerol. The solution was then dried in uacuo to avoid concentration changes during ionization. The resulting solution was diluted to prepare five different concentrations ranging from 0.8 to 4%. Only the main peaks (not all) of the mass spectrum were recorded. Those peaks corresponded to: glycerol fragment ions (mlz = 45, 57, 75), protonated glycerol molecular ion (mlz = 93), protonated glycerol dimer ion (mlz = 185), ions of nucleoside bases, nucleoside molecular ions, glycerol-nucleoside complex ions and nucleoside dimer * Author for correspondence.ions. In processing the mass spectra, the intensity of each peak was multiplied by the square root of its mlz in order to correct for different sensitivity of the electron multiplier to different mass ions.' These corrected intensities were then normalized to the sum of the intensities of all the main peaks in the given spectrum. The normalized intensities were employed in our modelling. At least eight samples ...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.