55 research outputs found

    Approximate solution of the Duffin-Kemmer-Petiau equation for a vector Yukawa potential with arbitrary total angular momenta

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    The usual approximation scheme is used to study the solution of the Duffin-Kemmer-Petiau (DKP) equation for a vector Yukawa potential in the framework of the parametric Nikiforov-Uvarov (NU) method. The approximate energy eigenvalue equation and the corresponding wave function spinor components are calculated for arbitrary total angular momentum in closed form. Further, the approximate energy equation and wave function spinor components are also given for case. A set of parameter values is used to obtain the numerical values for the energy states with various values of quantum levelsComment: 17 pages; Communications in Theoretical Physics (2012). arXiv admin note: substantial text overlap with arXiv:1205.0938, and with arXiv:quant-ph/0410159 by other author

    Ligand-Receptor Interactions

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    The formation and dissociation of specific noncovalent interactions between a variety of macromolecules play a crucial role in the function of biological systems. During the last few years, three main lines of research led to a dramatic improvement of our understanding of these important phenomena. First, combination of genetic engineering and X ray cristallography made available a simultaneous knowledg of the precise structure and affinity of series or related ligand-receptor systems differing by a few well-defined atoms. Second, improvement of computer power and simulation techniques allowed extended exploration of the interaction of realistic macromolecules. Third, simultaneous development of a variety of techniques based on atomic force microscopy, hydrodynamic flow, biomembrane probes, optical tweezers, magnetic fields or flexible transducers yielded direct experimental information of the behavior of single ligand receptor bonds. At the same time, investigation of well defined cellular models raised the interest of biologists to the kinetic and mechanical properties of cell membrane receptors. The aim of this review is to give a description of these advances that benefitted from a largely multidisciplinar approach

    Computer modeling of electrostatic steering and orientational effects in antibody-antigen association.

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    Brownian dynamics simulations are performed to investigate the role of long-range electrostatic forces in the association of the monoclonal antibody HyHEL-5 with hen egg lysozyme. The electrostatic field of the antibody is obtained from a solution of the nonlinear Poisson-Boltzmann using the x-ray crystal coordinates of this protein. The lysozyme is represented as an asymmetric dumbell consisting of two spheres of unequal size, an arrangement that allows for the modeling of the orientational requirements for docking. Calculations are done with the wild-type antibody and several point mutants at different ionic strengths. Changes in the charge distribution of the lysozyme are also considered. Results are compared with experiment and a simpler model in which the lysozyme is approximately by a single charged sphere

    Molecular cloning of the receptor for human antidiuretic hormone

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    Antidiuresis, the recovery of water from the lumen of the renal collecting tubule, is regulated by the hypothalamic release of antidiuretic hormone (ADH), which binds to specific receptors on renal collecting tubule cells, stimulates adenylyl cyclase and promotes the cyclic AMP-mediated incorporation of water pores into the luminal surface of these cells. We report here the isolation of the human ADH receptor gene using a genomic expression cloning approach. The gene was used to clone the complementary DNA from a human renal library. The deduced amino-acid sequence of the receptor yields a hydropathy profile characteristic of receptors with seven putative transmembrane regions. This and the comparison with other cloned receptors indicates that the ADH receptor is a member of the superfamily of G-protein-coupled receptors
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