Vliv vápníku na komplex calmodulin-melittin: Studie používající chemického zesítění a FTMS

Melittin binds tightly to calmodulin in the presence of calcium and inhibits the function o f calmodulin. Chemical cross-linking combined with mass spectrometry has been used in order to define the positions of Calmodulin and melittin in the complex at different concentrations of calciu

Monitoring conformational changes in protein complexes using chemical cross-linking and Fourier transform ion cyclotron resonance mass spectrometry : the effect of calcium binding on the calmodulin-melittin complex

Calmodulin is an EF hand calcium binding protein. Its binding affinities to various protein/peptide targets often depend on the conformational changes induced by the binding of calcium. One such target is melittin, which binds tightly to calmodulin in the presence of calcium, and inhibits its function. Chemical cross-linking combined with Fourier transform ion cyclotron resonance mass spectrometry has been employed to investigate the coordination of calmodulin and melittin in the complex at different concentrations of calcium. This methodology can be used to monitor structural changes in proteins induced by ligand binding and to study the effects these changes have on non-covalent interactions between proteins. Cross-linking results indicate that the binding place of the first melittin in the calcium-free calmodulin form is the same as in the calcium-loaded calmodulin/melittin complex

Theoretical investigation of the proton affinity and gas-phase basicity of neutral x,y-dihydroxybenzoic acid and its derivatives

Proton affinities (PA), gas-phase basicities (GB) and acidities (GA), which are some of the important physical properties of a matrix in matrix-assisted laser desorption ionization mass spectrometry, have been calculated using density functional theory (DFT) for a number of dihydroxybenzoic (DHB) acid isomers and derivatives. The theoretical PA and gas-phase basicity (GB) values for the neutral x,y-DHB acids, ionic radicals, Na+ and K+ salts as well as oxygen- and hydrogen-bridged dimers of x,y-DHB have been calculated. Analysis of the computational data indicates that there are lower PA/GB values for the anionic dimers compared to the PA/GB values for the electrically neutral oxygen-bridged dimers. The PA/GB values for the neutral and radical cations are larger than the neutral monomers and the PA/GB values for the radical anions are slightly lower than the anionic class of isomers. The PA/GB values for the salts (x, y-DHB-Na/K+) are significantly higher (100-150 kJ mol(-1)) than the neutral x,y-DHB acids. The above theoretical results are in agreement with experimental values obtained by Fourier transorm ion cyclotron resonance mass spectrometry employing a thermokinetic method. Correlation of experimentally and theoretically predicted values suggests that this theoretical calculation method could be used to derive information on different matrices

Parallelized Acquisition of Orbitrap and Astral Analyzers Enables High-Throughput Quantitative Analysis

The growing trend toward high-throughput proteomics demands rapid liquid chromatography–mass spectrometry (LC–MS) cycles that limit the available time to gather the large numbers of MS/MS fragmentation spectra required for identification. Orbitrap analyzers scale performance with acquisition time and necessarily sacrifice sensitivity and resolving power to deliver higher acquisition rates. We developed a new mass spectrometer that combines a mass-resolving quadrupole, the Orbitrap, and the novel Asymmetric Track Lossless (Astral) analyzer. The new hybrid instrument enables faster acquisition of high-resolution accurate mass (HRAM) MS/MS spectra compared with state-of-the-art mass spectrometers. Accordingly, new proteomics methods were developed that leverage the strengths of each HRAM analyzer, whereby the Orbitrap analyzer performs full scans with a high dynamic range and resolution, synchronized with the Astral analyzer’s acquisition of fast and sensitive HRAM MS/MS scans. Substantial improvements are demonstrated over previous methods using current state-of-the-art mass spectrometer