Вода в технологии производства хлебобулочных изделий с отложенной

In bakery water is used as a solvent for salt, sugar and other raw materials: for dough preparation, preparation of liquid yeast, starter cultures; goes for household needs cleaning of raw materials, equipment, premises, for heat engineering purposes — the production of steam necessary to humidify the air in proofing cabinets and ovens. Water plays an important role in the technology of delayed baking of bread products or in the technology of frozen semi-finished products: it is used during kneading to obtain an optimally developed gluten frame for better form and gas holding capacity; to obtain cold dough, which is the basis for slowing down the onset of the fermentation process, while fermentation should be minimized or completely absent; the amount of water affects the consistency of the dough for better dimensional stability during defrosting. Also, a low-temperature process, deep freezing strongly affects the structural and mechanical properties of the dough and the quality of the finished product; secondly, under certain parameters of freezing, the structure of the intracellular water of yeast can lead to a decrease in their activity, and even to the death of microorganisms. Therefore, the issues of the quality and quantity of water at any technological operation in bakery production with delayed baking are issues of the quality of finished products and therefore are very relevant.Вода в хлебопекарном производстве используется как растворитель соли, сахара и других видов сырья: для приготовления теста, приготовления жидких дрожжей, заквасок; для теплотехнических целей — производства пара, необходимого для увлажнения воздушной среды в расстойных шкафах и печах, а также идет на хозяйственные нужды мойку сырья, оборудования, помещений. Вода играет важную роль в технологии отложенной выпечки хлебных изделий и используется при замесе с получением оптимально развитого клейковинного каркаса для лучшей формо — и газоудерживающей способности; для получения холодного теста, что является основой для замедления начала процесса брожения, при этом брожение должно быть сведено к минимуму или полностью отсутствовать; количество воды влияет на консистенцию теста для лучшей формоустойчивости во время размораживания. Также низкотемпературный процесс, глубокая заморозка сильно влияет на структурно-механические свойства теста и качество готового продукта. При определенных параметрах замораживания структура внутриклеточной воды дрожжей может привести к снижению их активности, а то и к гибели микроорганизмов. Поэтому, вопросы качества и количества воды на любой технологической операции в хлебобулочном производстве с отложенной выпечкой являются вопросами качества готовых изделий и очень актуальны

Разработка соковых плодоовощных продуктов, обогащенных коллагеном

The beauty and aging of the human body is associated with such a protein substance as collagen. Our body’s ability to produce this biologically active component naturally and in the right amount becomes limited as we age. Collagen slows down the aging process of the skin, prevents injury, promotes wound healing, improves the absorption of amino acids, can help maintain or improve the biophysical properties of the skin (elasticity, moisture), reduce transepidermal water loss and solve the problem of skin roughness. The purpose of the research work is the development of the technology, recipes for food products — fruit and vegetable juices, drinks, enriched with animal or plant collagen. As a result, the assortment and quality of different types of collagen (tomato, beef, pork and fish) were studied. The organoleptic characteristics of this food additive were studied and the most preferred collagen sample for drinks was selected. The required amount of this substance has been determined, while ensuring the required quality of the drinks. The preservation of the active properties of various types of collagen in a drinking product was investigated. It was proved that beef collagen in an amount of 5% to the mass of the drink retains its active properties as much as possible, in terms of fractional composition — salt, alcohol, alkaline protein fractions. It has been shown that the amino acids methionine, tryptophan and hydroxyproline, which confirm the presence of collagen in the product, are contained in ready-made juice drinks enriched with collagen of beef origin. This type of collagen makes it possible to obtain drinks of “potable” quality, which is confirmed by organoleptic and physicochemical indicators. In general, the studies have shown that a new assortment of juice-containing fruit and vegetable products supplies the important biologically active component (collagen) to the human body.Красота и старение организма человека связаны с таким веществом-белком, как коллаген. Возможность нашего организма, с  возрастом, вырабатывать этот биологически активный компонент самостоятельно и в нужном количестве — ограниченна. Коллаген замедляет процессы старения кожи, предотвращает травмы, способствует заживлению ран, улучшает усвоение аминокислот, может помочь поддержать или улучшить биофизические свойства кожи — эластичность, влажность, снизить трансепидермальную потерю воды и решить проблему шероховатости кожи. Целью исследовательской работы является разработка технологии, рецептур пищевых продуктов — плодоовощных соков, напитков, обогащенных животным или растительным коллагеном. В  результате, изучен ассортимент и  качество разных видов коллагена — томатного, говяжьего, свиного и рыбного. Изучены органолептические показатели этой пищевой добавки и выбран наиболее предпочтительный образец коллагена для напитков. Определено требуемое количество этого вещества, при обеспечении необходимого качества напитков. Исследовано сохранение активных свойств различных видов коллагена в  питьевом продукте. Доказано, что говяжий коллаген в  количестве 5% к массе напитка, максимально сохраняет активные свойства, по фракционному составу — солевой, спиртовой, щелочной фракциям белка. Показано, что аминокислоты метионин, триптофан и оксипролин, являющиеся подтверждением наличия коллагена в  продукте, содержатся в  готовых соковых напитках, обогащенных коллагеном говяжьего происхождения. Этот вид коллагена позволяет получить напитки «питьевого» качества, что подтверждено органолептическими и  физико-химическими показателями. В целом исследования показали, что новый ассортимент сокосодержащих плодоовощных продуктов поставляет в организм человека важный биологически активный компонент — коллаген

Hierarchical Modeling of Activation Mechanisms in the ABL and EGFR Kinase Domains: Thermodynamic and Mechanistic Catalysts of Kinase Activation by Cancer Mutations

Structural and functional studies of the ABL and EGFR kinase domains have recently suggested a common mechanism of activation by cancer-causing mutations. However, dynamics and mechanistic aspects of kinase activation by cancer mutations that stimulate conformational transitions and thermodynamic stabilization of the constitutively active kinase form remain elusive. We present a large-scale computational investigation of activation mechanisms in the ABL and EGFR kinase domains by a panel of clinically important cancer mutants ABL-T315I, ABL-L387M, EGFR-T790M, and EGFR-L858R. We have also simulated the activating effect of the gatekeeper mutation on conformational dynamics and allosteric interactions in functional states of the ABL-SH2-SH3 regulatory complexes. A comprehensive analysis was conducted using a hierarchy of computational approaches that included homology modeling, molecular dynamics simulations, protein stability analysis, targeted molecular dynamics, and molecular docking. Collectively, the results of this study have revealed thermodynamic and mechanistic catalysts of kinase activation by major cancer-causing mutations in the ABL and EGFR kinase domains. By using multiple crystallographic states of ABL and EGFR, computer simulations have allowed one to map dynamics of conformational fluctuations and transitions in the normal (wild-type) and oncogenic kinase forms. A proposed multi-stage mechanistic model of activation involves a series of cooperative transitions between different conformational states, including assembly of the hydrophobic spine, the formation of the Src-like intermediate structure, and a cooperative breakage and formation of characteristic salt bridges, which signify transition to the active kinase form. We suggest that molecular mechanisms of activation by cancer mutations could mimic the activation process of the normal kinase, yet exploiting conserved structural catalysts to accelerate a conformational transition and the enhanced stabilization of the active kinase form. The results of this study reconcile current experimental data with insights from theoretical approaches, pointing to general mechanistic aspects of activating transitions in protein kinases

Conformational Determinants of Phosphotyrosine Peptides Complexed with the Src SH2 Domain

The inhibition of specific SH2 domain mediated protein-protein interactions as an effective chemotherapeutic approach in the treatment of diseases remains a challenge. That different conformations of peptide-ligands are preferred by different SH2 domains is an underappreciated observation from the structural analysis of phosphotyrosine peptide binding to SH2 domains that may aid in future drug design. To explore the nature of ligand binding, we use simulated annealing (SA) to sample the conformational space of phosphotyrosine-containing peptides complexed with the Src SH2 domain. While in good agreement with the crystallographic and NMR studies of high-affinity phosphopeptide-SH2 domain complexes, the results suggest that the structural basis for phopsphopeptide- Src SH2 interactions is more complex than the “two-pronged plug two-hole socket” model. A systematic study of peptides of type pYEEX, where pY is phosphotyrosine and X is a hydrophobic residue, indicates that these peptides can assume two conformations, one extended and one helical, representing the balance between the interaction of residue X with the hydrophobic hole on the surface of the Src SH2 domain, and its contribution to the inherent tendency of the two glutamic acids to form an α-helix. In contrast, a β-turn conformation, almost identical to that observed in the crystal structure of pYVNV bound to the Grb2 SH2 domain, predominates for pYXNX peptides, even in the presence of isoleucine at the third position. While peptide binding affinities, as measured by fluorescence polarization, correlate with the relative proportion of extended peptide conformation, these results suggest a model where all three residues C-terminal to the phosphotyrosine determine the conformation of the bound phosphopeptide. The information obtained in this work can be used in the design of specific SH2 domain inhibitors

Allosteric Interactions between the Myristate- and ATP-Site of the Abl Kinase

Abl kinase inhibitors targeting the ATP binding pocket are currently employed as potent anti-leukemogenic agents but drug resistance has become a significant clinical limitation. Recently, a compound that binds to the myristate pocket of Abl (GNF-5) was shown to act cooperatively with nilotinib, an ATP-competitive inhibitor to target the recalcitrant “T315I” gatekeeper mutant of Bcr-Abl. To uncover an explanation for how drug binding at a distance from the kinase active site could lead to inhibition and how inhibitors could combine their effects, hydrogen exchange mass spectrometry (HX MS) was employed to monitor conformational effects in the presence of both dasatinib, a clinically approved ATP-site inhibitor, and GNF-5. While dasatinib binding to wild type Abl clearly influenced Abl conformation, no binding was detected between dasatinib and T315I. GNF-5, however, elicited the same conformational changes in both wild type and T315I, including changes to dynamics within the ATP site located approximately 25 Å from the site of GNF-5 interaction. Simultaneous binding of dasatinib and GNF-5 to T315I caused conformational and/or dynamics changes in Abl such that effects of dasatinib on T315I were the same as when it bound to wild type Abl. These results provide strong biophysical evidence that allosteric interactions play a role in Abl kinase downregulation and that targeting sites outside the ATP binding site can provide an important pharmacological tool to overcome mutations that cause resistance to ATP-competitive inhibitors

Modeling Signal Propagation Mechanisms and Ligand-Based Conformational Dynamics of the Hsp90 Molecular Chaperone Full-Length Dimer

Hsp90 is a molecular chaperone essential for protein folding and activation in normal homeostasis and stress response. ATP binding and hydrolysis facilitate Hsp90 conformational changes required for client activation. Hsp90 plays an important role in disease states, particularly in cancer, where chaperoning of the mutated and overexpressed oncoproteins is important for function. Recent studies have illuminated mechanisms related to the chaperone function. However, an atomic resolution view of Hsp90 conformational dynamics, determined by the presence of different binding partners, is critical to define communication pathways between remote residues in different domains intimately affecting the chaperone cycle. Here, we present a computational analysis of signal propagation and long-range communication pathways in Hsp90. We carried out molecular dynamics simulations of the full-length Hsp90 dimer, combined with essential dynamics, correlation analysis, and a signal propagation model. All-atom MD simulations with timescales of 70 ns have been performed for complexes with the natural substrates ATP and ADP and for the unliganded dimer. We elucidate the mechanisms of signal propagation and determine “hot spots” involved in interdomain communication pathways from the nucleotide-binding site to the C-terminal domain interface. A comprehensive computational analysis of the Hsp90 communication pathways and dynamics at atomic resolution has revealed the role of the nucleotide in effecting conformational changes, elucidating the mechanisms of signal propagation. Functionally important residues and secondary structure elements emerge as effective mediators of communication between the nucleotide-binding site and the C-terminal interface. Furthermore, we show that specific interdomain signal propagation pathways may be activated as a function of the ligand. Our results support a “conformational selection model” of the Hsp90 mechanism, whereby the protein may exist in a dynamic equilibrium between different conformational states available on the energy landscape and binding of a specific partner can bias the equilibrium toward functionally relevant complexes

Probing Molecular Mechanisms of the Hsp90 Chaperone: Biophysical Modeling Identifies Key Regulators of Functional Dynamics

Deciphering functional mechanisms of the Hsp90 chaperone machinery is an important objective in cancer biology aiming to facilitate discovery of targeted anti-cancer therapies. Despite significant advances in understanding structure and function of molecular chaperones, organizing molecular principles that control the relationship between conformational diversity and functional mechanisms of the Hsp90 activity lack a sufficient quantitative characterization. We combined molecular dynamics simulations, principal component analysis, the energy landscape model and structure-functional analysis of Hsp90 regulatory interactions to systematically investigate functional dynamics of the molecular chaperone. This approach has identified a network of conserved regions common to the Hsp90 chaperones that could play a universal role in coordinating functional dynamics, principal collective motions and allosteric signaling of Hsp90. We have found that these functional motifs may be utilized by the molecular chaperone machinery to act collectively as central regulators of Hsp90 dynamics and activity, including the inter-domain communications, control of ATP hydrolysis, and protein client binding. These findings have provided support to a long-standing assertion that allosteric regulation and catalysis may have emerged via common evolutionary routes. The interaction networks regulating functional motions of Hsp90 may be determined by the inherent structural architecture of the molecular chaperone. At the same time, the thermodynamics-based “conformational selection” of functional states is likely to be activated based on the nature of the binding partner. This mechanistic model of Hsp90 dynamics and function is consistent with the notion that allosteric networks orchestrating cooperative protein motions can be formed by evolutionary conserved and sparsely connected residue clusters. Hence, allosteric signaling through a small network of distantly connected residue clusters may be a rather general functional requirement encoded across molecular chaperones. The obtained insights may be useful in guiding discovery of allosteric Hsp90 inhibitors targeting protein interfaces with co-chaperones and protein binding clients

The Energy Landscape Analysis of Cancer Mutations in Protein Kinases

The growing interest in quantifying the molecular basis of protein kinase activation and allosteric regulation by cancer mutations has fueled computational studies of allosteric signaling in protein kinases. In the present study, we combined computer simulations and the energy landscape analysis of protein kinases to characterize the interplay between oncogenic mutations and locally frustrated sites as important catalysts of allostetric kinase activation. While structurally rigid kinase core constitutes a minimally frustrated hub of the catalytic domain, locally frustrated residue clusters, whose interaction networks are not energetically optimized, are prone to dynamic modulation and could enable allosteric conformational transitions. The results of this study have shown that the energy landscape effect of oncogenic mutations may be allosteric eliciting global changes in the spatial distribution of highly frustrated residues. We have found that mutation-induced allosteric signaling may involve a dynamic coupling between structurally rigid (minimally frustrated) and plastic (locally frustrated) clusters of residues. The presented study has demonstrated that activation cancer mutations may affect the thermodynamic equilibrium between kinase states by allosterically altering the distribution of locally frustrated sites and increasing the local frustration in the inactive form, while eliminating locally frustrated sites and restoring structural rigidity of the active form. The energy landsape analysis of protein kinases and the proposed role of locally frustrated sites in activation mechanisms may have useful implications for bioinformatics-based screening and detection of functional sites critical for allosteric regulation in complex biomolecular systems