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991.
992.
N. S. Yudin V. Vinogradov Sergey Tatyana A. Potapova Tatyana M. Naykova Violetta V. Sitnikova Igor V. Kulikov Viacheslav I. Khasnulin Cheche Konchuk Pavel E. Vloschinskii Sergey V. Ivanov Viktor F. Kobzev Aida G. Romaschenko Mikhail I. Voevoda 《Human genetics》1998,102(6):695-698
32-bp inactivating deletion in the β-chemokine receptor 5 (CCR5) gene, common in Nothern European populations, is associated
with reduced HIV-1 transmission risk and delayed disease progression. We have studied the deletion distribution in many populations
in Eurasia by polymerase chain reaction analysis of 531 DNA samples representing West and East Siberian, Central Asian, and
Far Eastern parts of Russia. An unusually high frequency (11.1%) of the deleted variant in natives of West Siberia, of Finno-Ugrian
descent, was observed. Furthermore, the deletion was infrequent in indigenous populations of Central Asia, East Siberia, the
Russian Far East, and Canada. We conclude that the Δccr5 distribution is limited primarily to Europeans and related western
Siberian Finno-Ugrian populations, with a sharp negative gradient toward the east along the territory of Russian Asia.
Received: 22 December 1997 / Accepted: 24 March 1998 相似文献
993.
Computational modeling of the membrane channel of a sodium pump (Na,K-ATPase) is performed and the role of selected amino acids in binding of sodium ions is discussed. The channel is build as a pentameric 10-helix bundle. The transmembrane a-helices are determined from hydropathy calculations. The spatial arrangement of transmembrane a-helices is chosen according to the size of a pore, intersegment loops geometry, and orientation hydrophobicities of transmembrane segments. The latter property provides the numerical estimate of the distribution of the hydrophobic properties at the helical wheels. The model system involves the peptide part and 150 water molecules that soak the pore. The channel structure is submitted to geometry minimization and molecular dynamics relaxation. The relative stability of the channel states with the negatively charged acidic residues belonging to the pore interior decrease in the order Glu-334 > Asp-810 > Glu-785 > Asp-814. The estimated binding energies of 1-3 Na+ ions with the channel with the ionized Glu-334 and Glu-785 amino acids are in the range allowing the exothermic complexation.Electronic Supplementary Material available. 相似文献
994.
Thorsten Wöhl Hannelore Klier Hubert Ammer Friedrich Lottspeich Viktor Magdolen 《Molecular genetics and genomics : MGG》1993,241(3-4):305-311
In Saccharomyces cerevisiae, hypusine-containing proteins are encoded by two closely related genes, HYP1 and HYP2, which are regulated reciprocally by oxygen and heme. We have purified the aerobically expressed hypusine-containing proteins from yeast. The three proteins detected (two isoforms, which differ in their pI values, and a degradation product thereof, lacking the N-terminal 10 amino acid residues) are all encoded by HYP2. The N-terminus of both isoforms is formed by acetylation of a serine residue after cleavage of the first methionine. Cells mutant for hyp2 are unable to grow aerobically. However, under anaerobic conditions these mutants display no obvious phenotype, presumably because the strictly anaerobically expressed HYPI gene product (Hyp1p) is present. This implies that Hyp1p and Hyp2p fulfill very similar functions. In fact, Hyp1p can substitute for Hyp2p under aerobic conditions, when expressed under the control of the GAL1 promoter in hyp2 mutant cells. 相似文献
995.
996.
Viktor A. Zapol’skii Reiner Fischer Jan C. Namyslo Dieter E. Kaufmann 《Bioorganic & medicinal chemistry》2009,17(12):4206-4215
Nitropolychlorobutadienes are valuable precursors for highly functionalized acyclic or (hetero)cyclic compounds. In this 8th part of our synthetically oriented series we focus on the application of these versatile starting materials in the synthesis of analogs of the heterocyclic insecticides imidacloprid? and thiacloprid?, and the acyclic counterpart clothianidin?. In addition to the main synthetic part, leading to imidazolidines or oxazolidines, further promising types of compounds derived by subsequent chemical modifications, are introduced. Most of the new compounds show high insecticidal activity. 相似文献
997.
998.
Kenig M Gaberc-Porekar V Fonda I Menart V 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2008,867(1):119-125
The N-terminus of the trimeric TNF-alpha molecule comprises two basic arginines within the short amino-acid sequence VRSSSR, which is here shown to be essential for binding of TNF-alpha to heparin-Sepharose. Mixed trimers containing full-length and DeltaN6-truncated subunits revealed a single VRSSSR sequence to be sufficient to achieve binding. On the basis of this newly identified heparin-binding domain, a new method for efficient purification of TNF-alpha is described. Affinity chromatography on heparin-Sepharose was introduced as a key step for highly purified TNF-alpha at a high yield. With minor modifications, this procedure can be used for TNF-alpha analogues that have full-length N-termini, as shown for the less toxic analogue LK-805. 相似文献
999.
1000.
Viktor K. Jirsa 《Cognitive neurodynamics》2008,2(1):29-38
We study spike–burst neural activity and investigate its transitions to synchronized states under electrical coupling. Our
reported results include the following: (1) Synchronization of spike–burst activity is a multi-time scale phenomenon and burst
synchrony is easier to achieve than spike synchrony. (2) Synchrony of networks with time-delayed connections can be achieved
at lower coupling strengths than within the same network with instantaneous couplings. (3) The introduction of parameter dispersion
into the network destroys the existence of synchrony in the strict sense, but the network dynamics in major regimes of the
parameter space can still be effectively captured by a mean field approach if the couplings are excitatory. Our results on
synchronization of spiking networks are general of nature and will aid in the development of minimal models of neuronal populations.
The latter are the building blocks of large scale brain networks relevant for cognitive processing. 相似文献