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91.
Family of hemorphins: co-relations between amino acid sequences and effects in cell cultures 总被引:2,自引:0,他引:2
Blishchenko EY Sazonova OV Kalinina OA Yatskin ON Philippova MM Surovoy AY Karelin AA Ivanov VT 《Peptides》2002,23(5):903-910
Hemorphins, i.e. endogenous fragments of beta-globin chain segment (32-41) LVVYPWTQRY(F) suppress the growth of transformed murine fibroblasts L929 cell culture, the effect is due to cytotoxicity and inhibition of cell proliferation. The contribution of cytotoxicity depends on the presence of Leu(32): VV-hemorphins, except VV-hemorphin-4, exhibit cytotoxicity significantly higher than respective LVV-hemorphins. Decrease of cell number induced by hemorphins depend on the extent of N- and C-terminal degradation of hemorphins: VV-hemorphins in most cases are more active than LVV-, V-hemorphins, and hemorphins. In the group of VV-hemorphins the activity of VV-hemorphin-5 (valorphin) is significantly higher than of VV-hemorphin-7, VV-hemorphin-6, and VV-hemorphin-4, meaning that the presence of C-terminal Gln is important for suppressing of cell number. The amino acid sequence VVYPWTQ corresponding to valorphin was identified as important for manifestation of the both cytotoxic and antiproliferative effects. 相似文献
92.
Mammalian selenoprotein in which selenocysteine (Sec) incorporation is supported by a new form of Sec insertion sequence element
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Korotkov KV Novoselov SV Hatfield DL Gladyshev VN 《Molecular and cellular biology》2002,22(5):1402-1411
Selenocysteine (Sec), the 21st amino acid in protein, is encoded by UGA. The Sec insertion sequence (SECIS) element, which is the stem-loop structure present in 3' untranslated regions (UTRs) of eukaryotic selenoprotein-encoding genes, is essential for recognition of UGA as a codon for Sec rather than as a stop signal. We now report the identification of a new eukaryotic selenoprotein, designated selenoprotein M (SelM). The 3-kb human SelM-encoding gene has five exons and is located on chromosome 22 but has not been correctly identified by either Celera or the public Human Genome Project. We characterized human and mouse SelM cDNA sequences and expressed the selenoprotein in various mammalian cell lines. The 3" UTR of the human, mouse, and rat SelM-encoding genes lacks a canonical SECIS element. Instead, Sec is incorporated in response to a conserved mRNA structure, in which cytidines are present in place of the adenosines previously considered invariant. Substitution of adenosines for cytidines did not alter Sec incorporation; however, other mutant structures did not support selenoprotein synthesis, demonstrating that this new form of SECIS element is functional. SelM is expressed in a variety of tissues, with increased levels in the brain. It is localized to the perinuclear structures, and its N-terminal signal peptide is necessary for protein translocation. 相似文献
93.
Heat-induced formation of reactive oxygen species and 8-oxoguanine, a biomarker of damage to DNA 总被引:5,自引:0,他引:5
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Heat-induced formation of 8-oxoguanine was demonstrated in DNA solutions in 10–3 M phosphate buffer, pH 6.8, by enzyme-linked immunosorbent assays using monoclonal antibodies against 8-oxoguanine. A radiation-chemical yield of 3.7 × 10–2 µmol J–1 for 8-oxoguanine production in DNA upon γ-irradiation was used as an adequate standard for quantitation of 8-oxoguanine in whole DNA. The initial yield of heat-induced 8-oxoguanine exhibits first order kinetics. The rate constants for 8-oxoguanine formation were determined at elevated temperatures; the activation energy was found to be 27 ± 2 kcal/mol. Extrapolation to 37°C gave a value of k37 = 4.7 × 10–10 s–1. Heat-induced 8-oxoguanine formation and depurination of guanine and adenine show similarities of the processes, which implies that heat-mediated generation of reactive oxygen species (ROS) should occur. Heat-induced production of H2O2 in phosphate buffer was shown. The sequence of reactions of thermally mediated ROS formation have been established: activation of dissolved oxygen to the singlet state, generation of superoxide radicals and their dismutation to H2O2. Gas saturation (O2, N2 and Ar), D2O, scavengers of 1O2, O2–• and OH• radicals and metal chelators influenced heat-induced 8-oxoguanine formation as they affected thermal ROS generation. These findings imply that heat acts via ROS attack leading to oxidative damage to DNA. 相似文献
94.
Alekseenko SV Toporova SN Makarov FN 《Rossi?skii fiziologicheski? zhurnal imeni I.M. Sechenova / Rossi?skaia akademiia nauk》2002,88(3):324-328
Single cortical columns of areas 17, 18 in the cat were microiontophoretically injected with horseradish peroxidase. Spatial and laminar distributions of retrogradell labelled cells in both areas were investigated. Following injections in area 17 or in area 18 the labelled cells' region in area 17 was elongated (in a tangential plane) along the representation of visual field horizontal meridian. However the labelled cells' region in area 18 was elongated along the representation of vertical meridian. Such projection patterns appear to be common in these cortical areas throughout the central 10 degrees on various elevations (from -40 degrees to +10 degrees) of the visual field representation. Thus the spatial arrangement of intrinsic and extrinsic connections in each area coincides, at the same time in area 17 they are orthogonal to area 18. The following visual information exchange scheme may be suggested. Area 17 may supply the area 18 with more detailed information on the horizontal component of the visual image, and in the opposite direction the information on the vertical component of the same image may be supplied. 相似文献
95.
We investigated protein motions using normal modes within a database framework, determining on a large sample the degree to which normal modes anticipate the direction of the observed motion and were useful for motions classification. As a starting point for our analysis, we identified a large number of examples of protein flexibility from a comprehensive set of structural alignments of the proteins in the PDB. Each example consisted of a pair of proteins that were considerably different in structure given their sequence similarity. On each pair, we performed geometric comparisons and adiabatic-mapping interpolations in a high-throughput pipeline, arriving at a final list of 3,814 putative motions and standardized statistics for each. We then computed the normal modes of each motion in this list, determining the linear combination of modes that best approximated the direction of the observed motion. We integrated our new motions and normal mode calculations in the Macromolecular Motions Database, through a new ranking interface at http://molmovdb.org. Based on the normal mode calculations and the interpolations, we identified a new statistic, mode concentration, related to the mathematical concept of information content, which describes the degree to which the direction of the observed motion can be summarized by a few modes. Using this statistic, we were able to determine the fraction of the 3,814 motions where one could anticipate the direction of the actual motion from only a few modes. We also investigated mode concentration in comparison to related statistics on combinations of normal modes and correlated it with quantities characterizing protein flexibility (e.g., maximum backbone displacement or number of mobile atoms). Finally, we evaluated the ability of mode concentration to automatically classify motions into a variety of simple categories (e.g., whether or not they are "fragment-like"), in comparison to motion statistics. This involved the application of decision trees and feature selection (particular machine-learning techniques) to training and testing sets derived from merging the "list" of motions with manually classified ones. 相似文献
96.
97.
Localization of sucrose synthase and callose in freeze-substituted secondary-wall-stage cotton fibers 总被引:2,自引:0,他引:2
Summary. Methods for cryogenic fixation, freeze substitution, and embedding were developed to preserve the cellular structure and
protein localization of secondary-wall-stage cotton (Gossypium hirsutum L.) fibers accurately for the first time. Perturbation by specimen handling was minimized by freezing fibers still attached
to a seed fragment within 2 min after removal of seeds from a boll still attached to the plant. These methods revealed native
ultrastructure, including numerous active Golgi bodies, multivesicular bodies, and proplastids. Immunolocalization in the
context of accurate structure was accomplished after freeze substitution in acetone only. Quantitation of immunolabeling identified
sucrose synthase both near the cortical microtubules and plasma membrane and in a proximal exoplasmic zone about 0.2 μm thick.
Immunolabeling also showed that callose (β-1,3-glucan) was codistributed with sucrose synthase within this exoplasmic zone.
Similar results were obtained from cultured cotton fibers. The distribution of sucrose synthase is consistent with its having
a dual role in cellulose and callose synthesis in secondary-wall-stage cotton fibers.
Received August 19, 2002; accepted November 12, 2002; published online June 13, 2003
RID="*"
ID="*" Correspondence and reprints: Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409-3131, U.S.A.
E-mail: candace.haigler@ttu.edu 相似文献
98.
Demidov VV 《Trends in biotechnology》2003,21(4):148-151
Concatenation of hybridization probe with DNA target is crucial for highly localized detection of targeted sequences and might also be used in various gene-therapy applications. Several approaches based on the attachment of a circular oligonucleotide to designated DNA sites have been proposed. Recently, earring-like probes provide a true topological linkage between a probe and the target, thus allowing the DNA labeling by essentially immobile tags. The latest development in this direction takes advantage of oligonucleotide uptake by supercoiled DNA and is an important step forward. 相似文献
99.
Demidov VV 《Trends in biotechnology》2003,21(1):4-7
In some aspects, homogeneous (all-in-solution) nucleic acid hybridization assays are superior to the traditionally used heterogeneous (solution-to-surface) alternatives. Profluorescent probes, which reveal fluorescence enhancement or fluorescence polarization upon their binding to DNA and RNA targets, are a paradigm for the real-time sequence-specific homogeneous detection of nucleic acids. A variety of such DNA or RNA-derived probes of different constructs has already been developed with numerous applications. However, the recent additions to the field - locked nucleic acids (LNAs) and peptide nucleic acids (PNAs) - significantly increase the potential of profluorescent probes and provide a robust impulse for their new uses. 相似文献
100.
Archakov AI Govorun VM Dubanov AV Ivanov YD Veselovsky AV Lewi P Janssen P 《Proteomics》2003,3(4):380-391
Protein-protein interactions play a central role in numerous processes in the cell and are one of the main fields of functional proteomics. This review highlights the methods of bioinformatics and functional proteomics of protein-protein interaction investigation. The structures and properties of contact surfaces, forces involved in protein-protein interactions, kinetic and thermodynamic parameters of these reactions were considered. The properties of protein contact surfaces depend on their functions. The contact surfaces of permanent complexes resemble domain contacts or the protein core and it is reasonable to consider such complex formation as a continuation of protein folding. Characteristics of contact surfaces of temporary protein complexes share some similarities with active sites of enzymes. The contact surfaces of the temporary protein complexes have unique structure and properties and they are more conservative in comparison with active site of enzymes. So they represent prospective targets for a new generation of drugs. During the last decade, numerous investigations were undertaken to find or design small molecules that block protein dimerization or protein(peptide)-receptor interaction, or, on the contrary, to induce protein dimerization. 相似文献