Ресурсный центр «Магнитно-резонансные методы исследования»

M. Chizhova, D. Dar’in, M. Krasavin

“Complications in the Castagnoli-Cushman reaction: An unusual course of reaction between cyclic anhydrides and sterically hindered indolenines”

Tetrahedron Letters, 2017, 58(35), 3470-3473
DOI: 10.1016/j.tetlet.2017.07.077

Attempted reaction of indolenines (which represent rather sterically hindered cyclic imines) with a series of dicarboxylic acid anhydrides yielded no expected product, the Castagnoli-Cushman lactam. Instead, products presumably formed via N-acyliminium species trapping by a carboxylate anion. Among them, hydrolytically labile 2:2 adducts of an indolenine and a cyclic anhydride, containing a 16-membered cyclic core, are particularly intriguing. This result contradicts the recently reported successful Castagnoli-Cushman reaction of indolenines with homophthalic anhydride suggesting a mechanistic switch in the course of the reaction.

S. O. Rabdano, S. A. Izmailov, D. A. Luzik, A. Groves, I. S. Podkorytov, N. R. Skrynnikov

“Onsеt of Disоrdеr and Protein Aggregation Due to Oxidation-Induced Intermolecular Disulfide ”

Scientific Reports, 2017, 7, 11161
DOI: 10.1038/s41598-017-10574-w

We have investigated the behavior of second RNA-recognition motif (RRM2) of neuropathological protein TDP43 under the effect of oxidative stress as modeled in vitro. Toward this end we have used the specially adapted version of H/D exchange experiment, NMR relaxation and diffusion measurements, dynamic light scattering, controlled proteolysis, gel electrophoresis, site-directed mutagenesis and microsecond MD simulations. Under oxidizing conditions RRM2 forms disulfide-bonded dimers that experience unfolding and then assemble into aggregate particles (APs). These particles are strongly disordered, highly inhomogeneous and susceptible to proteolysis; some of them withstand the dithiothreitol treatment. They can recruit/release monomeric RRM2 through thiol-disulfide exchange reactions. By using a combination of dynamic light scattering and NMR diffusion data we were able to approximate the size distribution function for the APs. The key to the observed aggregation behavior is the diminished ability of disulfide-bonded RRM2 dimers to refold and their increased propensity to misfold, which makes them vulnerable to large thermal fluctuations. The emerging picture provides detailed insight on how oxidative stress can contribute to neurodegenerative disease, with unfolding, aggregation, and proteolytic cleavage as different facets of the process.

В Январе выполнено 1440 заявок на сервисные измерения.

Измерено:

• 1294 спектр ¹H
• 247 спектра ¹³C
• 61 спектров DEPT
• 29 спектров COSY
• 17 спектра NOESY
• 72 спектра ³¹Р
• 58 спектров ¹⁹F

Выполнено 163 заявок на исследовательскую работу.

S. Kalinin, S. Kopylov, T. Tuccinardi, A. Sapegin, D. Dar’in, A. Angeli, C.T. Supuran, M. Krasavin

“Lucky Switcheroo: Dramatic Potency and sеlеctivity Improvement of Imidazoline Inhibitors of Human Carbonic Anhydrase VII”

ACS Med. Chem. Lett, 2017, 8 (10), 1105–1109.
DOI: 10.1021/acsmedchemlett.7b00300

A substantial improvement of potency and selectivity of imidazoline-based inhibitors of hCA VII (a promising target for the treatment of seizures and neuropathic pain) was achieved by simply switching the position of the benzenesulfonamide moiety from N1 (as in the earlier reported series) to C2. Selectivity indices vs the off-target isoforms (hCA I, I, I and IV) greater than 100 were reached, which is exceedingly rare for hCA VII inhibitors. The drastic profile improvement of the new series has been rationalized by an additional hydrogen bonding with the nonconserved Q69 residue in the active site of hCA VII (absent in the other three isoforms studied), which also results in a favorable accommodation of the inhibitor’s lipophilic periphery in the nearby hydrophobic pocket. The robustness of the docking simulations was tested and confirmed by molecular dynamics simulations

Ресурсный центр МРМИ посетила делегация Технологического университета имени Шарифа (Sharif University of Technology). В рамках встречи обсуждались возможные перспективы сотрудничества.

Эта картинка не имеет прямого отношения к магнитно-резонансным методам исследования, однако, возможно, поднимет вам настроение.

E.V. Abakumov, O.A. Rodina, A.K. Eskov

“Humification and Humic Acid Composition of Suspended
Soil in Oligotrophous Environments in South Vietnam”

Applied and Environmental Soil Science, 2018, Article ID 1026237.
DOI: 10.1155/2018/1026237

Humification is considered to be a global process that is implemented in soils and organic sediments and also in natural water and air. The term “suspended soils” has become increasingly common in recent years. Suspended soils are defined as the part of the organic matter that has not undergone the full decomposition process and has not turned into the humus of terrestrial soils. Suspended soils were shown to contain higher total nitrogen, phosphorus, and potassium contents than the forest soil, but the moisture content in suspended soils was significantly lower. Our study of the structural composition of humic substances in suspended soils was conducted with an aim of evaluating the humification rates and structural composition of humic acids in the suspended soil in tropical forests of South Vietnam. Soil samples from three selected areas were investigated: the soil under phorophytes (mineral soil presented by samples of topsoil of the typical dry savanna landscape) and two soils from epiphytous formations. Samples were collected from savanna-type sparse communities, located on oligotrophous plains in Phú Quốc Island (South Vietnam) in 2015. General properties of the soil and the elemental composition of suspended soils were determined, and the humic substance chemical composition was evaluated using solid state 13C-NMR. Data obtained showed that the pH of the soils under phorophytes was higher than in the suspended soils; basal respiration did not tend to change indices between soils under phorophytes and suspended soils, but the suspended soil was less enriched by nitrogen than the soil under phorophytes. This can be related to the total amount of organic matter exposed to humification in various soils and to the presence of an essential portion of mineral particles in the soil under phorophytes. Data on elemental composition of the humic acids (HAs) indicated that one method of humification is implemented in all three soils that were investigated. The humic acids of the phorophyte soil showed the same content of aromatic fraction as the suspended soil. The most comparable soil type in terms of humic substance composition is Cambisols from humid forests of subboreal and subtropical zones. The humification process implemented in suspended soils showed the absence of mineral compounds or mineral fine earth, which indicated that humification in conditions of pure organic substrates can result in formation of deep humified organic matter, as shown by humic acids with an essential aromatic fraction content.