Understanding the non-catalytic behavior of human butyrylcholinesterase silent variants: Comparison of wild-type enzyme, catalytically active Ala328Cys mutant, and silent Ala328Asp variant

© 2016 Elsevier Ireland LtdConformational dynamics of wild-type human butyrylcholinesterase (BChE), two mutants of residue Ala328, the catalytically active Ala328Cys, and the catalytically inactive (silent) Ala328Asp, and their interactions with butyrylcholine were studied. The aim was to understand the molecular mechanisms by which point mutations may lead to silent BChE variant or alter catalytic activity. Importance of BChE natural variants is due to medical consequences, i.e. prolonged apnea, following administration of the myorelaxant esters, succinylcholine and mivacurium. Comparison of molecular dynamics (MD) simulations for the three model systems showed that: 1) the active mutant Ala328Cys mutant has some changes in configuration of catalytic residues, which do not prevent binding of butyrylcholine to the active site; 2) in the naturally-occurring silent variant Ala328Asp, the Asp328 carboxylate may either form a salt bridge with Lys339 or a H-bond with His438. In the first case, the Ω-loop swings off the gorge, disrupting the π-cation binding site and the catalytic triad. In the second case, binding of cationic substrates in the catalytic center is also impaired. MD simulations carried out in 0.15 M NaCl, close to physiological ionic strength conditions, favored the second situation. It was seen that Asp328 forms a H-bond with the catalytic triad His438, which in turn disrupts the catalytic machinery. Therefore, we concluded that the Ala328Asp variant is not catalytically active because of that dramatic event. Computational results, consistent with in vitro biochemical data and clinical observations, validate our MD approach

Understanding the non-catalytic behavior of human butyrylcholinesterase silent variants: Comparison of wild-type enzyme, catalytically active Ala328Cys mutant, and silent Ala328Asp variant

© 2016 Elsevier Ireland Ltd.Conformational dynamics of wild-type human butyrylcholinesterase (BChE), two mutants of residue Ala328, the catalytically active Ala328Cys, and the catalytically inactive (silent) Ala328Asp, and their interactions with butyrylcholine were studied. The aim was to understand the molecular mechanisms by which point mutations may lead to silent BChE variant or alter catalytic activity. Importance of BChE natural variants is due to medical consequences, i.e. prolonged apnea, following administration of the myorelaxant esters, succinylcholine and mivacurium.Comparison of molecular dynamics (MD) simulations for the three model systems showed that: 1) the active mutant Ala328Cys mutant has some changes in configuration of catalytic residues, which do not prevent binding of butyrylcholine to the active site; 2) in the naturally-occurring silent variant Ala328Asp, the Asp328 carboxylate may either form a salt bridge with Lys339 or a H-bond with His438. In the first case, the Ω-loop swings off the gorge, disrupting the π-cation binding site and the catalytic triad. In the second case, binding of cationic substrates in the catalytic center is also impaired. MD simulations carried out in 0.15 M NaCl, close to physiological ionic strength conditions, favored the second situation. It was seen that Asp328 forms a H-bond with the catalytic triad His438, which in turn disrupts the catalytic machinery. Therefore, we concluded that the Ala328Asp variant is not catalytically active because of that dramatic event. Computational results, consistent with in vitro biochemical data and clinical observations, validate our MD approach

История и дальнейшие задачи развития программы ЮНЕСКО «Человек и биосфера» (МАБ) и сети биосферных резерваторов в России

The review describes the subject of the UNESCO Man and the Biosphere (MAB) program and how the network of Russian biosphere reserves was developed. The MAB Program is designed to coordinate the efforts of scientists from many countries who conduct fundamental research in order to reduce anthropogenic impact and the gap between consumption and conservation. Tendencies of population growth and migration, growing demands for energy and natural resources, globalization of the economy, centralization of management, the difficulty of access to necessary information — all these factors have a direct or indirect impact on the environment, and hence on the prospects for human survival and development. According to UNESCO official documents biosphere reserves are protected zones of a representative terrestrial and coastal environment that have gained international recognition because of their importance for nature protection, scientific knowledge and skills, and the preservation of human values for sustainable development. To date, the World Network of Biosphere Reserves includes 686 such protected areas in 122 countries, including 20 transboundary ones.Данный обзор повествует о том, что является предметом Программы ЮНЕСКО «Человек и биосфера» (МАБ — от англ. Man and the Biosphere) и как развивается система биосферных резерватов России. Программа ЮНЕСКО «Человек и биосфера» (МАБ) призвана координировать усилия ученых многих стран, которые проводят фундаментальные исследования, чтобы уменьшить антропогенное влияние и сократить разрыв между потреблением и сохранением. Тенденции роста и миграции населения, растущие запросы на энергию и природные ресурсы, глобализация экономики, централизация управления, трудность доступа к необходимой информации — все эти факторы оказывают прямое или косвенное воздействие на состояние окружающей среды, а значит и на перспективы развития человечества. Согласно официальным документам ЮНЕСКО, именно биосферные резерваты являются охраняемыми зонами репрезентативной наземной и прибрежной окружающей среды, которые получили международное признание в силу их значения для охраны природы, обеспечения научных знаний и профессиональных навыков, сохранения человеческих ценностей — в целях устойчивого развития. К настоящему времени во Всемирную сеть биосферных резерватов входит 686 таких ООПТ в 122 странах, включая 20 трансграничных

Molecular polymorphism of human enzymes as the basis of individual sensitivity to drugs. Supercomputer-assisted modeling as a tool for analysis of structural changes and enzymatic activity of proteins

© 2016, Springer Science+Business Media New York.The nature of individual sensitivity to drugs associated with molecular polymorphism of human enzymes is discussed. The influence of molecular polymorphism on the activity of key human esterases, in particular, cholinesterases and carboxylesterase, responsible for hydrolytic metabolism of ester-containing drugs, is analyzed. A method was developed, which involves supercomputer-assisted modeling as a tool for assessment of molecular mechanism of the impact of point mutations on the catalytic activity of enzymes. This work is a part of a study aimed at elaboration of the concept and methods of personalized medicine

Macrocyclic derivatives of 6-methyluracil as ligands of the peripheral anionic site of acetylcholinesterase

© the Partner Organisations 2014. Novel pyrimidinophanes possessing two o-nitrobenzylethyldialkylammonium heads bridging with different spacers were prepared. Pyrimidinophanes 2a, 2b and 3 are reversible inhibitors of cholinesterases. They show a very good selectivity for human acetylcholinesterase (AChE), with an inhibitory power 100-200 times higher than for human butyrylcholinesterase (BChE). Docking simulations indicate specific binding of pyrimidinophanes 2a and 4 onto the peripheral anionic site of AChE. Other compounds bind to the active center of AChE as well as to the peripheral anionic site. These compounds are dual binding site inhibitors. Pyrimidinophane 2b and its acyclic counterpart 1 were tested in the animal model of myasthenia gravis and may be considered as valuable candidates for the treatment of pathological muscle weakness syndromes. This journal i

Slow-binding inhibition of acetylcholinesterase by an alkylammonium derivative of 6-methyluracil: Mechanism and possible advantages for myasthenia gravis treatment

© 2016 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.Inhibition of human AChE (acetylcholinesterase) and BChE (butyrylcholinesterase) by an alkylammonium derivative of 6-methyluracil, C-547, a potential drug for the treatment of MG (myasthenia gravis) was studied. Kinetic analysis of AChE inhibition showed that C-547 is a slow-binding inhibitor of type B, i.e. after formation of the initial enzyme•inhibitor complex (Ki = 140 pM), an induced-fit step allows establishment of the final complex (Ki = 22 pM). The estimated koff is low, 0.05 -1 . On the other hand, reversible inhibition of human BChE is a fast-binding process of mixed-type (Ki = 1.77 μM; Ki = 3.17 μM). The crystal structure of mouse AChE complexed with C-547 was solved at 3.13 Å resolution. The complex is stabilized by cation-π , stacking and hydrogenbonding interactions. Molecular dynamics simulations of the binding/dissociation processes of C-547 and C-35 (a noncharged analogue) to mouse and human AChEs were performed. Molecular modelling on mouse and human AChE showed that the slow step results from an enzyme conformational change that allows C-547 to cross the bottleneck in the active-site gorge, followed by formation of tight complex, as observed in the crystal structure. In contrast, the related non-charged compound C-35 is not a slow-binding inhibitor. It does not cross the bottleneck because it is not sensitive to the electrostatic driving force to reach the bottom of the gorge. Thus C-547 is one of the most potent and selective reversible inhibitors of AChE with a long residence time, τ; = 20 min, longer than for other reversible inhibitors used in the treatment of MG. This makes C-547 a promising drug for the treatment of this disease

6-methyluracil derivatives as bifunctional acetylcholinesterase inhibitors for the treatment of Alzheimer's disease

© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Novel 6-methyluracil derivatives with ω-(substituted benzylethylamino)alkyl chains at the nitrogen atoms of the pyrimidine ring were designed and synthesized. The numbers of methylene groups in the alkyl chains were varied along with the electron-withdrawing substituents on the benzyl rings. The compounds are mixed-type reversible inhibitors of cholinesterases, and some of them show remarkable selectivity for human acetylcholinesterase (hAChE), with inhibitory potency in the nanomolar range, more than 10 000-fold higher than that for human butyrylcholinesterase (hBuChE). Molecular modeling studies indicate that these compounds are bifunctional AChE inhibitors, spanning the enzyme active site gorge and binding to its peripheral anionic site (PAS). In vivo experiments show that the 6-methyluracil derivatives are able to penetrate the blood-brain barrier (BBB), inhibiting brain-tissue AChE. The most potent AChE inhibitor, 3 d (1,3-bis[5-(o-nitrobenzylethylamino)pentyl]-6-methyluracil), was found to improve working memory in scopolamine and transgenic APP/PS1 murine models of Alzheimer's disease, and to significantly decrease the number and area of β-amyloid peptide plaques in the brain. Head-AChE relief! In our efforts to identify compounds to treat Alzheimer′s disease, we found that 1,3-bis[ω-(substituted benzylethylamino)alkyl]-6-methyluracils bind to the active site gorge and peripheral anionic site of acetylcholinesterase (AChE). These compounds can cross the blood-brain barrier, and decrease the number and area of β-amyloid plaques in the brain

Derivatives of 9-phosphorylated acridine as butyrylcholinesterase inhibitors with antioxidant activity and the ability to inhibit β-amyloid self-aggregation: potential therapeutic agents for Alzheimer’s disease

We investigated the inhibitory activities of novel 9-phosphoryl-9,10-dihydroacridines and 9-phosphorylacridines against acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and carboxylesterase (CES). We also studied the abilities of the new compounds to interfere with the self-aggregation of β-amyloid (Aβ42) in the thioflavin test as well as their antioxidant activities in the ABTS and FRAP assays. We used molecular docking, molecular dynamics simulations, and quantum-chemical calculations to explain experimental results. All new compounds weakly inhibited AChE and off-target CES. Dihydroacridines with aryl substituents in the phosphoryl moiety inhibited BChE; the most active were the dibenzyloxy derivative 1d and its diphenethyl bioisostere 1e (IC50 = 2.90 ± 0.23 µM and 3.22 ± 0.25 µM, respectively). Only one acridine, 2d, an analog of dihydroacridine, 1d, was an effective BChE inhibitor (IC50 = 6.90 ± 0.55 μM), consistent with docking results. Dihydroacridines inhibited Aβ42 self-aggregation; 1d and 1e were the most active (58.9% ± 4.7% and 46.9% ± 4.2%, respectively). All dihydroacridines 1 demonstrated high ABTS•+-scavenging and iron-reducing activities comparable to Trolox, but acridines 2 were almost inactive. Observed features were well explained by quantum-chemical calculations. ADMET parameters calculated for all compounds predicted favorable intestinal absorption, good blood–brain barrier permeability, and low cardiac toxicity. Overall, the best results were obtained for two dihydroacridine derivatives 1d and 1e with dibenzyloxy and diphenethyl substituents in the phosphoryl moiety. These compounds displayed high inhibition of BChE activity and Aβ42 self-aggregation, high antioxidant activity, and favorable predicted ADMET profiles. Therefore, we consider 1d and 1e as lead compounds for further in-depth studies as potential anti-AD preparations

Biological Earth observation with animal sensors.

Space-based tracking technology using low-cost miniature tags is now delivering data on fine-scale animal movement at near-global scale. Linked with remotely sensed environmental data, this offers a biological lens on habitat integrity and connectivity for conservation and human health; a global network of animal sentinels of environmen-tal change

History and further tasks of the development of the UNESCO program «Man and the Biosphere» and biosphere reserves network in Russia

The review describes the subject of the UNESCO Man and the Biosphere (MAB) program and how the network of Russian biosphere reserves was developed. The MAB Program is designed to coordinate the efforts of scientists from many countries who conduct fundamental research in order to reduce anthropogenic impact and the gap between consumption and conservation. Tendencies of population growth and migration, growing demands for energy and natural resources, globalization of the economy, centralization of management, the difficulty of access to necessary information — all these factors have a direct or indirect impact on the environment, and hence on the prospects for human survival and development. According to UNESCO official documents biosphere reserves are protected zones of a representative terrestrial and coastal environment that have gained international recognition because of their importance for nature protection, scientific knowledge and skills, and the preservation of human values for sustainable development. To date, the World Network of Biosphere Reserves includes 686 such protected areas in 122 countries, including 20 transboundary ones