Characteristic of activity of enterprises of the fuel and energy complex of Russia on introduction of innovation technologies and equipment Характеристика деятельности предприятий топливно-энергетического комплекса России по внедрению инновационных технологий и оборудования

Competitiveness of enterprises of the fuel and energy complex of Russia is determined now by efficiency of innovation activity. Technological innovations that are capable of increasing efficiency of development of hydrocarbons are developed and offered for introduction at all stages: from survey and exploration to processing of petroleum and natural gas.<br>Конкурентоспособность предприятий топливно-энергетического комплекса (ТЭК) России в настоящее время определяется эффективностью инновационной деятельности. Технологические инновации, способные повысить эффективность освоения углеводородов, сегодня разработаны и предложены для внедрения на всех стадиях: от поиска и разведки до переработки нефти и газа

Defining CYP3A4 Structural Responses to Substrate Binding. Raman Spectroscopic Studies of a Nanodisc-incorporated Mammalian Cytochrome P450

Resonance Raman (RR) spectroscopy is used to help define active site structural responses of nanodisc-incorporated CYP3A4 to the binding of three substrates: bromocriptine (BC), erythromycin (ERY), and testosterone (TST). We demonstrate that nanodisc-incorporated assemblies reveal much more well-defined active site RR spectroscopic responses as compared to those normally obtained with the conventional, detergent-stabilized, sampling strategies. While ERY and BC are known to bind to CYP3A4 with a 1:1 stoichiometry, only the BC induces a substantial conversion from low- to high-spin state, as clearly manifested in the RR spectra acquired herein. The third substrate, TST, displays significant homotropic interactions within CYP3A4, the active site binding up to 3 molecules of this substrate, with the functional properties varying in response to binding of individual substrate molecules. While such behavior seemingly suggests the possibility that each substrate binding event induces functionally important heme structural changes, up to this time spectroscopic evidence for such structural changes has not been available. The current RR spectroscopic studies show clearly that accommodation of different size substrates, and different loading of TST, do not significantly affect the structure of the substrate-bound ferric heme. However, it is here demonstrated that the nature and number of bound substrates do have an extraordinary influence on the conformation of bound exogenous ligands, such as CO or dioxygen and its reduced forms, implying an effective mechanism whereby substrate structure can impact reactivity of intermediates so as to influence function, as reflected in the diverse reactivity of this drug metabolizing cytochrome

The Use of Isomeric Testosterone Dimers to Explore Allosteric Effects in Substrate Binding to Cytochrome P450 CYP3A4

Abstract: Cytochrome P450 CYP3A4 is the main drug-metabolizing enzyme in the human liver, being responsible for oxidation of 50% of all pharmaceuticals metabolized by human P450 enzymes. Possessing a large substrate binding pocket, it can simultaneously bind several substrate molecules and often exhibits a complex pattern of drug–drug interactions. In order to better understand structural and functional aspects of binding of multiple substrate molecules to CYP3A4 we used resonance Raman and UV–VIS spectroscopy to document the effects of binding of synthetic testosterone dimers of different configurations, cis-TST2 and trans-TST2. We directly demonstrate that the binding of two steroid molecules, which can assume multiple possible configurations inside the substrate binding pocket of monomeric CYP3A4, can lead to active site structural changes that affect functional properties. Using resonance Raman spectroscopy, we have documented perturbations in the ferric and Fe-CO states by these substrates, and compared these results with effects caused by binding of monomeric TST. While the binding of trans-TST2 yields results similar to those obtained with monomeric TST, the binding of cis-TST2 is much tighter and results in significantly more pronounced conformational changes of the porphyrin side chains and Fe-CO unit. In addition, binding of an additional monomeric TST molecule in the remote allosteric site significantly improves binding affinity and the overall spin shift for CYP3A4 with trans-TST2 dimer bound inside the substrate binding pocket. This result provides the first direct evidence for an allosteric effect of the peripheral binding site at the protein-membrane interface on the functional properties of CYP3A4. Graphical abstract: Synthetic dimers of the steroid testosterone are used to address directly the mechanisms of multiple substrate binding at the active site of cytochrome P450 3A4 and the role of substrate binding at a distal site in the control of allostery in this central enzyme of human drug metabolism

Generalized parton distributions: Status and perspectives

We summarize recent developments in understanding the concept of generalized parton distributions (GPDs), its relation to nucleon structure, and its application to high-Q2 electroproduction processes. Following a brief review of QCD factorization and transverse nucleon structure, we discuss (a) new theoretical methods for the analysis of deeply-virtual Compton scattering (t-channel-based GPD parametrizations, dispersion relations); (b) the phenomenology of hard exclusive meson production (experimental tests of dominance of small-size configurations, model-independent comparative studies); (c) the role of GPDs in small-x physics and pp scattering (QCD dipole model, central exclusive diffraction). We emphasize the usefulness of the transverse spatial (or impact parameter) representation for both understanding the reaction mechanism in hard exclusive processes and visualizing the physical content of the GPDs.Comment: 10 pages, 6 figures. Proceedings of SPIN2008, University of Virginia, October 6-11, 200

The strong coupling constant at large distances

In this paper we discuss effective strong coupling constants. Those are well behaved in the low-Q^2 domain, contrarily to alpha_s from pQCD. We present an extraction of an effective strong coupling constant from Jefferson Lab polarized data at intermediate and low Q^2. We also show how these data, together with spin sum rules, allow us to obtain the effective coupling constant over the entire Q^2 range. We then discuss the relation between the experimentally extracted coupling constant and theoretical calculations at low Q^2. We conclude on the importance of such study for the application of the AdS/CFT correspondence to QCD.Comment: Proceedings for Spin2008 symposium. v2: added 2 referecences re. infrared fixed poin

Generalized parton distributions, the hunt for quark orbital momenta

The Generalized Parton Distributions (GPDs) are the appropriate framework for a universal description of the partonic structure of the nucleon. They characterize the dynamics of quarks and gluons inside the nucleon and consequently contain information about the spin of the nucleon. The current experimental knowledge about GPDs is reviewed with the emphasis on the determination of E^q(Q^2,x,xi,t), the least known and constrained GPD, of particular importance in the nucleon spin puzzle. The perspectives of this experimental program are also addressed.Comment: 6 pages, 2 figures Proceedings of the XVIIIth Symposium on Spin Physics, Charlottesville (Virginia, USA), October 6-11,200

Parton Distributions in the Impact Parameter Space

Parton distributions in impact parameter space, which are obtained by Fourier transforming GPDs, exhibit a significant deviation from axial symmetry when the target and/or quark is transversely polarized. In combination with the final state interactions, this transverse deformation provides a natural mechanism for naive-T odd transverse single-spin asymmetries in semi-inclusive DIS. The deformation can also be related to the transverse force acting on the active quark in polarized DIS at higher twist.Comment: 9 pages, Proceedings Spin 200