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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 31 (1998), S. 445-452 
    ISSN: 0887-3585
    Keywords: chorismate mutase ; activity ; allosteric ; electrostatics ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The predicted active site of chorismate mutase of baker's yeast Saccharomyces cerevisiae has been studied by continuum electrostatics, molecular surface/volume calculations, and molecular modeling. Our study shows that despite being subject to an allosteric transition, the enzyme's active-site pocket neither decreased in volume nor deformed significantly in shape between the active R state and the inactive T state. We find that the polar atmosphere in the pocket is responsible for the enzyme's affinity. A single amino acid, Glu23, can adequately account for the atmospheric variation. This residue swings into the active-site pocket from the R state to the T state. In the R state, Glu23 on helix H2 doubly pairs with Arg204 and Lys208 of H11, which is packed against H2. In the T state, a slide occurs between H11 and H2 such that Glu23 can no longer interact with Lys208 and competes with Asp24 for interacting with Arg204. Consequently, Glu23 is found in the T state to couple with Arg157, an active-site residue critical to substrate binding. The tandem sliding of H11 in both monomers profoundly changes the interactions in the dimer interface. The loop between H11 and H12 demonstrates the largest conformational change. Hence, we establish a connection between the allosteric transition and the activity of the enzyme. The conformational change in the transition is suggested to propagate into the active-site pocket via a series of polar interactions that result in polarity reversal in the active-site pocket, which regulates the enzyme's activity. Proteins 31:445-452, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0887-3585
    Keywords: molecular recognition ; flexible docking ; protein-ligand interaction ; induced fit ; structure-based drug design ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Here we dock a ligand onto a receptor surface allowing hinge-bending domain/substructural movements. Our approach mimics and manifests induced fit in molecular recognition. All angular rotations are allowed on the one hand, while a conformational space search is avoided on the other. Rather than dock each of the molecular parts separately with subsequent reconstruction of the consistently docked molecules, all parts are docked simultaneously while still utilizing the position of the hinge from the start. Like pliers closing on a screw, the receptor automatically closes on its ligand in the best surface-matching way. Movements are allowed either in the ligand or in the larger receptor, hence reproducing induced molecular fit. Hinge bending movements are frequently observed when molecules associate. There are numerous examples of open versus closed conformations taking place upon binding. Such movements are observed when the substrate binds to its respective enzyme. In particular, such movements are of interest in allosteric enzymes. The movements can involve entire domains, subdomains, loops, (other) secondary structure elements, or between any groups of atoms connected by flexible joints. We have implemented the hinges at points and at bonds. By allowing 3-dimensional (3-D) rotation at the hinge, several rotations about (consecutive or nearby) bonds are implicitly taken into account. Alternatively, if required, the point rotation can be restricted to bond rotation. Here we illustrate this hinge-bending docking approach and the insight into flexibility it provides on a complex of the calmodulin with its M13 ligand, positioning the hinges either in the ligand or in the larger receptor. This automated and efficient method is adapted from computer vision and robotics. It enables utilizing entire molecular surfaces rather than focusing a priori on active sites. Hence, allows attaining the overall optimally matching surfaces, the extent and type of motions which are involved. Here we do not treat the conformational flexibility of side-chains or of very small pieces of the molecules. Therefore, currently available methods addressing these issues and the method presented here, are complementary to each other, expanding the repertoire of computational docking tools foreseen to aid in studies of recognition, conformational flexibility and drug design. Proteins 32:159-174, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 18 (1994), S. 94-101 
    ISSN: 0887-3585
    Keywords: surface representation ; molecular recognition ; protein docking ; surface triangulation ; molecular graphics ; molecular visualization ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: We have defined a molecular surface representation that describes precisely and concisely the complete molecular surface. The representation consists of a limited number of critical points disposed at key locations over the surface. These points adequately represent the shape and the important characteristics of the surface, despite the fact that they are modest in number. We expect the representation to be useful in areas such as molecular recognition and visualization. In particular, using this representation, we are able to achieve accurate and efficient protein-protein and protein-small molecule docking. © 1994 John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 16 (1993), S. 278-292 
    ISSN: 0887-3585
    Keywords: protein structural comparison ; 3-D protein motifs ; surface motifs ; docking ; computer vision ; geometric hashing ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: We describe the application of a method geared toward structural and surface comparison of proteins. The method is based on the Geometric Hashing Paradigm adapted from Computer Vision. It allows for comparison of any two sets of 3-D coordinates, such as protein backbones, protein core or protein surface motifs, and small molecules such as drugs. Here we apply our method to 4 types of comparisons between pairs of molecules: (1) comparison of the backbones of two protein domains; (2) search for a predefined 3-D Cα motif within the full backbone of a domain; and in particular, (3) comparison of the surfaces of two receptor proteins; and (4) comparison of the surface of a receptor to the surface of a ligand. These aspects complement each other and can contribute toward a better understandingof protein structure and biomolecular recognition. Searches for 3-D surface motifs can be carried out on either receptors or on ligands. The latter may result in the detection of pharmacophoric patterns. If the surfaces of the binding sites of either the receptors or of the ligands are relatively similar, surface superpositioning may aid significantly in the docking problem. Currently, only distance invariants are used in the matching, although additional geometric surface invariants are considered. The speed of our Geometric Hashing algorithm is encouraging, with a typical surface comparison taking only seconds or minutes of CPU time on a SUN 4 SPARC workstation. The direct application of this method to the docking problem is also discussed. We demonstrate the success of this methodin its application to two members of the globin family and to two dehydrogenases. © 1993 Wiley-Liss, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0887-3585
    Keywords: van der Waals radius ; Coulombic radius ; docking ; molecular surface ; solvent-accessible surface ; protein-protein interface ; protein-water boundary ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: We analyze the contact distance distributions between nonbonded atoms in known protein structures. A complete set of van der Waals (VDW) radii for 24 protein atom types and for crystal-bound water is derived from the contact distance distributions of these atoms with a selected group of apolar atoms. In addition, a set of Coulombic radii for polar atoms is derived from their contacts with water. The contact distance distributions and the two sets of radii are derived in a systematic and self-consistent manner using an iterative procedure. The Coulombic radii for polar atoms are, on average, 0.18 Å smaller than their VDW radii. The VDW radius of water is 1.7 Å, which is 0.3 Å larger than its Coulombic radius. We show that both the VDW and the Coulombic radii of polar atoms are needed in calculating the molecular and solvent-accessible surfaces of proteins. The VDW radii are needed to generate the apolar portions of the surface and the Coulombic radii for the polar portions. The fact that polar atoms have two apparent sizes implies that a hydrophobic cavity has to be larger than a polar cavity in order to accommodate the same number of water molecules. Most surface area calculations have used only one radius for each polar atom. As a result, unreal cavities, grooves, or pockets may be generated if the Coulombic radii of polar atoms are used. On the other hand, if the VDW radii of polar atoms are used, the details of the polar regions of the surface may be lost. The accuracy of the molecular and the solvent-accessible surfaces of proteins can be improved if the radii of polar atoms are allowed to change depending on the nature of their contacting neighbors. The surface of a protein at a protein-protein interface differs from that in solution in that it has to be generated using at least two kinds of probes, one representing a typical apolar atom and the other a typical polar atom. This observation has important implications for docking, which relies on surface complementarity at the interface. Proteins 32:111-127, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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