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排序方式: 共有279条查询结果,搜索用时 11 毫秒
1.
Roman G. Efremov Dmitry I. Gulyaev Gerard Vergoten Nikolai N. Modyanov 《Journal of Protein Chemistry》1992,11(6):665-675
A new computer-aided molecular modeling approach based on the concept of three-dimensional (3D) molecular hydrophobicity potential has been developed to calculate the spatial organization of intramembrane domains in proteins. The method has been tested by calculating the arrangement of membrane-spanning segments in the photoreaction center ofRhodopseudomonas viridis and comparing the results obtained with those derived from the X-ray data. We have applied this computational procedure to the analysis of interhelical packing in membrane moiety of Na+, K+-ATPase. The work consists of three parts. In Part I, 3D distributions of electrostatic and molecular hydrophobicity potentials on the surfaces of transmembrane helical peptides were computed and visualized. The hydrophobic and electrostatic properties of helices are discussed from the point of view of their possible arrangement within the protein molecule. Interlocation of helical segments connected with short extramembrane loops found by means of optimization of their hydrophobic/hydrophilic contacts is considered in Part II. The most probable 3D model of packing of helical peptides in the membrane domain of Na+, K+-ATPase is discussed in the final part of the work. 相似文献
2.
Surface-enhanced Raman (SER) spectra of purple membranes of Halobacterium halobium and photoreceptor disks of the rod outer segments adsorbed on silver hydrosols were analysed. It has been shown that the intensity of SER spectra of bacterial and visual rhodopsins increases 5 X 10(4) times at adsorption. Concentration relationship of the signal intensity of SER spectra has the maximum at bacteriorhodopsin concentration about 2 X 10(-7) M. It has been shown that adsorption on silver hydrosol leads to fixation of light-induced photochemical transformations in bacterial and visual rhodopsins. Adsorption on the "smooth" electrodes at the potential of the zero charge of silver does not affect the photocycle of bacteriorhodopsin. An increase or decrease of the electrode potential relative to the zero charge point of silver leads to the accumulation of kinetic intermediate K610 and a decrease of the concentration of the form BRh570. It has been shown that on the "smooth" electrode primarily the long-range component of the SER mechanism is realized. Bands corresponding to the vibrations of the atom groups directly contacting with the metal are mainly intensified after redox cycle which increases the concentration of chemosorption centres. A conclusion is drawn that the method of SER spectroscopy of biomolecules adsorbed on "smooth" electrodes, permits obtaining information similar to that obtained from the analysis of Raman spectra of unadsorbed molecules, but at concentrations by two orders less. Adsorption on the electrodes treated with the help of redox cycle permits to obtain highly oriented preparations and to study topography of biopolymers in water solutions and suspensions. 相似文献
3.
Ferdane Kutlar Jose M. Gonzalez-Redondo Abdullah Kutlar Aytemiz Gurgey Çigdem Altay Georgi D. Efremov Klara Kleman Titus H. J. Huisman 《Human genetics》1989,82(2):179-186
Summary Details are given of a study of blood samples from 24 patients with Hb H disease from different Mediterranean countries and from the Far East. Four different types of -thal-1 (--) were observed, namely-() ( 20.5-kb deletion);--MED-I ( 17.5-kb deletion);--MED-II (>26.5-kb deletion); and--SEA ( 18-kb deletion, in Orientals only). The -thal-2 was mainly of the deletion type (16 with the 3.7-kb deletion; 1 with the 4.2-kb deletion), while 4 of the 7 patients with a nondeletional type had the five-nucleotide deletion at the donor splice site of the first intron of the 2 gene. All patients had a mild-to-moderate hemolytic anemia; no significant differences in hematology were observed between the groups. Hb A2 was decreased to about one-third of the normal level. The Hb H formation varied considerably and its quantitation was not always satisfactory. Patients with Hb H disease due to any -thal-1 combined with a nondeletional -thal-2 had the highest Hb H levels and a more marked anemia. The chain production was small and absent in patients with the MED-II type of -thal-1 because this deletion included the and genes. The highest chain levels were present in the four patients with the SEA type of -thal-1. The chain production was increased, particularly in patients with a mutation of C T at position-158 to the G globin gene. This chain was primarily present as Hb Bart's (or 4) and only about 15% was recovered as Hb F or 22. The evaluation of the rate of chains produced in these patients was greatly facilitated by data from one patient who had Hb H disease and a heterozygosity for the A-+. The low levels of Hb A2 and of Hb F (relative to Hb Bart's) can be explained by a decreased affinity of chains for and chains as compared with chains in conditions of severe chain deficiency. 相似文献
4.
Ibragimova SI Kozlov DG Kartasheva NN Sutsov NI Efremov BD Benevolensky SV 《Biotechnology and bioengineering》1995,46(3):285-290
A procedure was developed for construction of industrial strains of distiller's yeast (Saccharomyces cerevisiae). It includes several steps: construction of congenic genetically marked haploid strains of opposite mating types starting from an industrial strain of hybrid nature, integrative transformation of the above haploid strains with a DNA fragment containing an expression cassette responsible for new technological facilities, and hybridization of transformants and isolation of final industrial homozygous strains under experimental conditions simulating commercial fermentation processes. This strategy permits the generation of strains that have desirable characteristics of traditional races of distiller's yeast along with new technological facilities determined by the particular expression cassette. Using this procedure, we have constructed an industrial strain with improved amylolytic activity. (c) 1995 John Wiley & Sons, Inc. 相似文献
5.
Valentin M. Tabakmakher Andrei M. Gigolaev Steve Peigneur Nikolay A. Krylov Jan Tytgat Anton O. Chugunov Alexander A. Vassilevski Roman G. Efremov 《Biophysical journal》2021,120(12):2471-2481
The α-Hairpinins are a family of plant defense peptides with a common fold presenting two short α-helices stabilized by two invariant S–S-bridges. We have shown previously that substitution of just two amino acid residues in a wheat α-hairpinin Tk-AMP-X2 leads to Tk-hefu-2 that features specific affinity to voltage-gated potassium channels KV1.3. Here, we utilize a combined molecular modeling approach based on molecular dynamics simulations and protein surface topography technique to improve the affinity of Tk-hefu-2 to KV1.3 while preserving its specificity. An important advance of this work compared with our previous studies is transition from the analysis of various physicochemical properties of an isolated toxin molecule to its consideration in complex with its target, a membrane-bound ion channel. As a result, a panel of computationally designed Tk-hefu-2 derivatives was synthesized and tested against KV1.3. The most active mutant Tk-hefu-10 showed a half-maximal inhibitory concentration of ~150 nM being >10 times more active than Tk-hefu-2 and >200 times more active than the original Tk-hefu. We conclude that α-hairpinins provide an attractive disulfide-stabilized scaffold for the rational design of ion channel inhibitors. Furthermore, the success rate can be considerably increased by the proposed “target-based” iterative strategy of molecular design. 相似文献
6.
7.
M. E. Palkeeva M. V. Sidorova A. S. Molokoedov A. A. Az’muko Zh. D. Bespalova T. V. Sharf E. N. Mamochkina E. E. Efremov M. M. Rogova N. A. Mironova K. A. Zykov S. P. Golitsyn 《Russian Journal of Bioorganic Chemistry》2013,39(3):252-258
Fragments corresponding to the 83–98 sequence of the first extracellular loop and to the 168–192 and 171–182 sequences of the second extracellular loop of the M2-muscarinic receptor (antibodies to this receptor could be markers of early symptoms of heart disorders) were synthesized by solid phase method using the Fmoc-SPPS strategy. A new conformational antigen with the natural location of the disulfide bridge was prepared by selective formation of disulfide bond between the corresponding cysteine residues in the synthe-sized peptides and characterized. The comparative analysis of reactivity of the synthesized peptides towards sera from patients which had no organic heart disease was performed. A new conformational antigen was effectively bound to the sera from patients with idiopathic arrhythmias, but without symptoms of organic heart disease. 相似文献
8.
Tabakmakher V. M. Kuzmenkov A. I. Gigolaev A. M. Pinheiro-Junior E. L. Peigneur S. Efremov R. G. Tytgat J. Vassilevski A. A. 《Journal of Evolutionary Biochemistry and Physiology》2021,57(2):386-403
Journal of Evolutionary Biochemistry and Physiology - In mammals, about 40 isoforms of voltage-gated potassium channels (KVs) have been found. To study such a variety of KVs, substances are needed... 相似文献
9.
Evgenia V. Dolgova Yaroslav R. Efremov Konstantin E. Orishchenko Oleg M. Andrushkevich Ekaterina A. Alyamkina Anastasia S. Proskurina Sergey I. Bayborodin Valeriy P. Nikolin Nelly A. Popova Elena R. Chernykh Alexandr A. Ostanin Oleg S. Taranov Vladimir V. Omigov Alexandra M. Minkevich Vladimir A. Rogachev Sergey S. Bogachev Mikhail A. Shurdov 《Gene》2013
We previously reported that fragments of exogenous double-stranded DNA can be internalized by mouse bone marrow cells without any transfection. Our present analysis shows that only 2% of bone marrow cells take up the fragments of extracellular exogenous DNA. Of these, ~ 45% of the cells correspond to CD34 + hematopoietic stem cells. Taking into account that CD34 + stem cells constituted 2.5% of the total cell population in the bone marrow samples analyzed, these data indicate that as much as 40% of CD34 + cells readily internalize fragments of extracellular exogenous DNA. This suggests that internalization of fragmented dsDNA is a general feature of poorly differentiated cells, in particular CD34 + bone marrow cells. 相似文献
10.
Yuri A. Kosinsky Peter V. Dubovskii Dmitry E. Nolde Alexander S. Arseniev Roman G. Efremov 《Molecular simulation》2013,39(4-6):341-349
Abstract Conformation of 20-residue peptide E5, an analog of the fusion peptide of influenza virus hemagglutinin, was explored by Monte-Carlo technique starting with the fully buried in the membrane ideal α-helix. The lipid bilayer (of 30 Å width) together with surrounding water were modeled by the atomic solvation parameters. During the simulation, residues 2–18 of the peptide retained α-helical conformation, and the peptide was found to be partially immersed into the bilayer. In the resulting low-energy conformers, the N-terminus was buried inside the membrane, its position with respect to the bilayer surface (ZNT) being varied from 2.5 to 7.5 Å, and the orientation of the helical axis relative to the membrane plane (Θ) – from 10 to 35°. The low-energy conformers (below -200kcal/mol) were clustered in the space (ZNT, Θ) into 4 groups. To select low-energy states of the peptide compatible with NMR data, we calculated pKa values of E5 ionizable groups and compared them with the experimental values. It was shown that the best correlation coefficient (0.87) and rmsd (0.68 in pH units) were obtained for the group of states which is characterized by Θ = 15–19° and ZNT = 3.5–4.5Å. 相似文献