• Molecular interactions between ribosomal proteins — An analysis of S7-S9, S7-S19, S9-S19 and S7-S9-S19 interactions

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    • Keywords


      Ribosomal proteins; S7, S9 and S19; interaction; equilibrium constant; 30S ribosome; free energy of interaction

    • Abstract


      Ribosomal proteins S7, S9 and S 19 fromEscherichia coli have been studied by the sedimentation equilibrium technique for possible intermolecular interaction between pairs of proteins as well as in a mixture of 3 proteins. The proteins were isolated to a purity greater than 95% and were characterized in the reconstitution buffer. It was observed that none of the proteins has a tendency to self-associate in the concentration range studied in the temperature range 3–6°C. Protein S9 behaves differently in the presence of other proteins. Analysis of the sedimentation equilibrium data for S7-S9, S9-S19 and S7-S9-S19 complexes revealed the need for considering the presence of a component of higher molecular weight in the system along with the monomers and their complexes to provide a meaningful curve-fitting of the data. Proteins S7 and S19 were found to interact with an equilibrium constant of association of 3 ± 2 × 104 M−1 at 3°C with a Gibbs free energy of interaction ΔG° of −5·7 kcal/mol. These data are useful for the consideration of the stabilization of the 3 0S subunit through protein-protein interactions and also help in building a topographical model of the proteins of the small subunit from an energetics point of view.

    • Author Affiliations


      V Prakash1

      1. Biophysical Chemistry Unit, Food Chemistry Department, Central Food Technological Research Institute, Mysore - 570 013, India
    • Dates

  • Journal of Biosciences | News

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