Spectroscopic studies of peptide fragments produced by collision-induced dissociation

Tandem mass spectrometry (MS/MS) combined with collision-induced dissociation (CID) is a key method for primary structure determination of peptides and proteins. Collisionally activated peptides undergo statistical dissociation, forming a series of backbone bn and yn fragment ions that reflect the peptide sequence. However, nascent CID fragments may undergo sequence permutation via "head-to-tail" cyclization, and upon further dissociation give rise to non-direct fragments, hindering the mass spectral interpretation. In this thesis work laser spectroscopy in a cold ion trap is used to provide structural information on the nascent fragments, which can help elucidate the fragmentation mechanisms and predict the occurrence of sequence permutation. The first part of the work is devoted to the b6 fragment ion formed from the protonated model peptide [FAGFAGPG + H]+. For this species five unique conformations have been identified under our experimental conditions. Nitrogen-15 isotopic substitution of individual amino acid residues reveals two intriguing totally symmetric cyclic species. This analysis also provides unambiguous evidence for proton migration during CID for the remaining asymmetric conformers. This information, as well as the vibrational band assignments, simplified the conformational search performed by simulated annealing combined with DFT calculations. The superb agreement between experiment and theory provided a high degree of confidence in the determined structures. To our knowledge this is the first conformer-selective spectroscopic identification of the cyclic bn ions implicated in sequence scrambling during CID. The second part describes the experiments in which the barriers to conformational isomerization have been probed by IR hole-filling spectroscopy (HFS). The HFS recorded in the fundamental as well as in the first overtone NH stretch vibration regions are presented. The next part describes the experiments in which the influence of amino acid composition and length of bn ions on their structural aspects have been investigated. The b6 ions from [FAVFAGPG + H]+ and [YAGYAGPG + H]+ are described first. Based on the comparison of their IR-UV spectra with those of b6 [FAGFAGPG + H]+, some structural features of the former are deduced. For the larger b8 ion from [FAVGFAVGPG + H]+, we have identified six unique conformers, one of which has a totally symmetric cyclic structure. The last part describes construction and characterization of a new cryogenic octopole ion trap. Its advantages over the previously used 22-pole trap are demonstrated

Management of the Innovative Digital Technology Implementation in the Regions

The article defines the goals of digital transformation of companies, highlights the main distinctive elements of digitalization of enterprises, and classifies the factors that affect the speed of digital transformation. The authors assessed the level of digital economy development in Russia, Ukraine and developed countries over the period of 2007-2020 according to the International Digital Economy and Society Index (I-DESI) as well as the Global Innovation Index (GII). The change in the ranking of individual countries according to the GII is presented, top ten leading countries in each group are identified. The authors compare the most popular innovative technological trends, present the expected payback periods for investments in digital solutions in Russia and the world, determine the barriers that hinder the development of digitalization in companies. The analysis carried out shows that against the background of a significant slowdown in the global economic growth, there are concerns about a reduction in R&D, venture capital and intellectual property

Problems of loan population in Russia

The article is devoted to the consideration of such a phenomenon as the debt load of the country’s population on the example of Russia. The term “debt” means the ratio between debt obligations and available income. Assessing the level of debt or, in other words, the debt burden of Russian citizens is relevant, because real disposable incomes have a rather long downward trend, and consumer unsecured lending is becoming more affordable, the amount of debt to Russians to creditors is increasing year by year, while the share of overdue liabilities, although not very large, still poses certain risks. This situation increases the level of debt to citizens, which poses serious challenges for the socio-economic development of the state, since excessive debt burden can lead to a crisis (as, for example, in the USA in 2008). Therefore, it is especially important to soberly assess the level of debt load and take appropriate measures in time to regulate it, in particular, to cool the consumer lending market as the most volatile segment of lending to individuals

Accurate bond dissociation energy of water determined by triple-resonance vibrational spectroscopy and ab initio calculations

Triple-resonance vibrational spectroscopy is used to determine the lowest dissociation energy, D0, for the water isotopologue HD16O as 41 239.7 ± 0.2 cm−1 and to improve D0 for H216O to 41 145.92 ± 0.12 cm−1. Ab initio calculations including systematic basis set and electron correlation convergence studies, relativistic and Lamb shift effects as well as corrections beyond the Born–Oppenheimer approximation, agree with the measured values to 1 and 2 cm−1 respectively. The improved treatment of high-order correlation terms is key to this high theoretical accuracy. Predicted values for D0 for the other five major water isotopologues are expected to be correct within 1 cm−1

Cryogenic Spectroscopy and Quantum Molecular Dynamics Determine the Structure of Cyclic Intermediates Involved in Peptide Sequence Scrambling

Collision-induced dissociation (CID) is a key technique used in mass spectrometry-based peptide sequencing. Collisionally activated peptides undergo statistical dissociation, forming a series of backbone fragment ions that reflect their amino acid (AA) sequence. Some of these fragments may experience a “head-to-tail” cyclization, which after proton migration, can lead to the cyclic structure opening in a different place than the initially formed bond. This process leads to AA sequence scrambling that may hinder sequencing of the initial peptide. Here we combine cryogenic ion spectroscopy and <i>ab initio</i> molecular dynamics simulations to isolate and characterize the precise structures of key intermediates in the scrambling process. The most stable peptide fragments show intriguing symmetric cyclic structures in which the proton is situated on a <i>C</i>₂ symmetry axis and forms exceptionally short H-bonds (1.20 Å) with two backbone oxygens. Other nonsymmetric cyclic structures also exist, one of which is protonated on the amide nitrogen, where ring opening is likely to occur

The food security as a priority area of russian policy

The purpose of the study is to provide a comprehensive analysis of the current state of food security in the Russian Federation and identify existing problems in this area, since this problem is more relevant than ever in Russia, given the complex socio-political situation. Used in the work: a system approach (considering food security as an essential element of national security), situational and functional (considering the monitor changes the status of food security as a information technology management), statistical monitoring (provides guidance to build predictive judgments), qualitative (proclaims the need for multi-criteria diagnosis of food security). as well as formal logical and dialectical methods of cognition. Formal-legal and comparative-legal methods of cognition were used as private-scientific methods. The normative base of the study is the national security Strategy of the Russian Federation, as well as the food security doctrine Of the Russian Federation.The study of the state of food security in Russia shows that the Russian Federation has formed an integral system for maintaining this sphere at the proper level. The analysis allows us to conclude that, despite the sanctions imposed on Russia, the system of public administration in General allows us to regulate processes in the food sector and provide the population with basic agricultural products. The guarantee of achieving food security is the stability of domestic production, as well as the availability of necessary reserves and stocks. In this regard, it can be argued to some extent that the food security system operates with a sufficient level of efficiency. At the same time, the sanctions and anti-sanctions imposed have created a number of obstacles to the normal functioning of the interstate system for the exchange of agricultural products

Air quality observations onboard commercial and targeted Zeppelin flights in Germany – a platform for high-resolution trace-gas and aerosol measurements within the planetary boundary layer

Abstract. A Zeppelin airship was used as a platform for in-situ measurements of greenhouse gases and short-lived air pollutants within the planetary boundary layer in Germany. A novel quantum cascade laser-based multi-compound gas analyzer (MIRO Analytical AG) was deployed to simultaneously measure in-situ concentrations of greenhouse gases (CO2, N2O, H2O, and CH4) and air pollutants (CO, NO, NO2, O3, SO2, and NH3) with high precision at a measurement rate of 1 Hz. These measurements were complemented by electrochemical sensors for NO, NO2, Ox (NO2+O3), and CO, an optical particle counter, temperature, humidity, altitude, and position monitoring. Instruments were operated remotely without the need for on-site interactions. Three two-week campaigns were conducted in 2020 comprising commercial passenger as well as targeted flights over multiple German cities including Cologne, Mönchengladbach, Düsseldorf, Aachen, Frankfurt, but also over industrial areas and highways. Vertical profiles of trace gases were obtained during the airship landing and take-off. Diurnal variability of the Zeppelin vertical profiles was compared to measurements from ground-based monitoring stations with a focus on nitrogen oxides and ozone. We find that their variability can be explained by the increasing nocturnal boundary layer height from early morning towards midday, an increase in emissions during rush hour traffic, and the rapid photochemical activity midday. Higher altitude (250–450 m) NOX to CO ratios are further compared to the 2015 EDGAR emission inventory to find that pollutant concentrations are influenced by transportation and residential emissions as well as manufacturing industries and construction activity. Finally, we report NOx and CO concentrations from one plume transect originating from a coal power plant and compare it to the EURAD-IM model to find agreement within 15 %. However, due to the increased contribution of solar and wind energy and/or the impact of lockdown measures the power plant was operated at max. 50 % capacity; therefore, possible overestimation of emissions by the model cannot be excluded