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Tytuł oryginału: Functional maps of the junctions between interglobular contacts and active sites in glycolytic enzymes - a comparative analysis of the biochemical and structural data.
Autorzy: Torshin Ivan Y.
Źródło: Med. Sci. Monitor 2002: 8 (4) s.BR123-BR135, il., tab., bibliogr. 47 poz.
Sygnatura GBL: 313,278

Hasła klasyfikacyjne GBL:
  • mikrobiologia

    Typ dokumentu:
  • praca doświadczalna
  • tytuł obcojęzyczny

    Wskaźnik treści:
  • zwierzęta

    Streszczenie angielskie: Oligomers and separate subunits of the glycolytic enzymes often have different catalytic properties. However, spectral data show an apparent lack of significant conformational changes during oligomerization. Since the conformation of an enzyme determines its catalytic properties, the structural mechanism(s) influencing the activity is of considerable interest. Analysis of the spatial structures of the junctions between interglobular contacts and binding sites may give a clue to the mechanism(s) of the activation. In this work, the problem was studied using available structural and biochemical data for the oligomeric enzymes of glycolysis. Computational analysis of the structures of the junctions has identified three structurally distinct types of junctions: 1. interglobular binding site (2 of 8 enzymes); 2. domain-domain stabilization (5 of 8); and 3. 'sequence overlap' or a local conformational change (all enzymes). Thus the catalytic activity may be influenced through the shifts of the modules of protein structure (types 1,2) and/or due to a slight change in the local structure (type 3). The more common junctions of types 2 and 3 are well conserved among eukaryotic enzymes, which suggests their biological importance. The results suggest that a profound and a complex change in conformation in subunits of an oligomeric enzyme may not be necessary for a significant change in the catalytic properties. The analysis maps the residues important for the junctions and thus for the link between the catalytic activity and the oligomeric state of the enzymes.


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    Tytuł oryginału: Structural criteria of biologically active RGD-sites for analysis of protein cellular function - a bioinformatics study.
    Autorzy: Torshin Ivan Y.
    Źródło: Med. Sci. Monitor 2002: 8 (8) s.BR301-BR312, il., tab., bibliogr. 73 poz.
    Sygnatura GBL: 313,278

    Typ dokumentu:
  • praca doświadczalna
  • tytuł obcojęzyczny

    Streszczenie angielskie: Background: Cell adhesion involves interactions of integrins and extracellular proteins, often facilitated by the RGD motif. Only presence of the RGD in a sequence of a protein may be not sufficient for the biological activity (binding to an integrin) and additional biochemical and/or structural studies are essential. Material/Methods: Structural criteria that would allow identification biologically active RGD-sites on the base of a spatial structure may assist analysis of function of a protein in the cell. For the first time, computational analysis of RGD-sites in a large non-redundant set of protein structures was done. Results: out of 3819 protein chains sequences of about 100 contained RGDs. Analysis of the structures of the RGD-'native' proteins has allowed establishing main determinants of the biologically active conformations of the RGD sites: surface accessibility of the whole RGD-sequence and the secondary structure. The criteria, applied to the reamining proteins of the set, identify 23 proteins (~ 25 p.c.) with potentially active RGD-sites. The results strongly suggest that RGD has a high propensity for being involved in protein-protein interactions and this may explain occurrence of RGDs in intracellular proteins. Results of the analysis suggest (in some cases, confirm) novel integrin-related activities for 7 membrane/extracellular proteins, as well as confirm RGD-facilitated cell attachment for 5 viral proteins. Conclusions: Only presence of RGD in a sequence is not sufficient to propose biological activity of this site. The results also suggest that the method can be used on large scale: for example, for identifying potential integrin-interacting proteins in an animal genome.

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