Georges Pavlov

Publications (4)8 Total impact

• Source

  Available from: PubMed Central

  Article: Hydrodynamic properties of cyclodextrin molecules in dilute solutions.

  Georges M Pavlov, Evguenia V Korneeva, Natalia A Smolina, Ulrich S Schubert
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  ABSTRACT: Three well-known representatives of the cyclodextrin family were completely characterized by molecular hydrodynamics methods in three different solvents. For the first time the possibility of an estimation of velocity sedimentation coefficients s between 0.15 and 0.5 S by the numerical solution of the Lamm equation is shown. Comparison of the experimental hydrodynamic characteristics of the cyclodextrins with theoretical calculations for toroidal molecules allows an estimation of the thickness of the solvent layers on the surface of cyclodextrin molecules.
  Biophysics of Structure and Mechanism 02/2009; 39(3):371-9. · 2.44 Impact Factor
• Article: Organization of human interferon gamma-heparin complexes from solution properties and hydrodynamics.

  Horacio Perez Sanchez, Karine Tatarenko, Michael Nigen, Georges Pavlov, Anne Imberty, Hugues Lortat-Jacob, Jose Garcia de la Torre, Christine Ebel
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  ABSTRACT: Heparan sulfate (HS) recognizes a variety of proteins, one of which is the pleiotropic cytokine IFN-gamma, and as such modulates many biological processes. IFN-gamma is a homodimer with a well-defined core and two flexible C-termini that constitute HS binding domains. We show here using molecular modeling that an extended IFN-gamma structure overlaps a HS fragment of 16 disaccharides (16 nm). Since a 21-24-disaccharide HS fragment was experimentally defined as the minimum size that interacts with IFN-gamma [Lortat-Jacob, H., Turnbull, J. E., and Grimaud, J. A. (1995) Biochem. J. 310 (Part 2), 497-505], this raises the question of the complexe organization. We combine analytical ultracentrifugation, size exclusion chromatography, and hydrodynamic bead modeling to characterize the complexes formed in solution with heparin oligosaccharides. For oligosaccharides of 14 and 20 nm, two types of complexes are formed with one IFN-gamma and one or two heparin molecules. Complexes consisting of two IFN-gamma and one or two heparin molecules are present for a fragment of 25 nm and aggregates for a fragment of 35 nm. The complexes are rather compact and can be formed without major conformational changes of the partners. The complex pattern of interaction is related to the size of the partners and their multiple binding possibilities. These various possibilities suggest networks of interactions at the crowded surface of the cells. Hydrodynamic methods used here proved to be very efficient tools for describing protein-HS complexes that, due to the intrinsic heterogeneity and flexibility of the partners, are otherwise very difficult to analyze.
  Biochemistry 12/2006; 45(44):13227-38. · 3.42 Impact Factor
• Article: Organization of Human Interferon γ−Heparin Complexes from Solution Properties and Hydrodynamics†

  Horacio Perez Sanchez, Karine Tatarenko, Michael Nigen, Georges Pavlov, Anne Imberty, Hugues Lortat-Jacob, Jose Garcia de la Torre, Christine Ebel
  [show abstract] [hide abstract]
  ABSTRACT: Heparan sulfate (HS) recognizes a variety of proteins, one of which is the pleiotropic cytokine IFN-γ, and as such modulates many biological processes. IFN-γ is a homodimer with a well-defined core and two flexible C-termini that constitute HS binding domains. We show here using molecular modeling that an extended IFN-γ structure overlaps a HS fragment of 16 disaccharides (16 nm). Since a 21−24-disaccharide HS fragment was experimentally defined as the minimum size that interacts with IFN-γ [Lortat-Jacob, H., Turnbull, J. E., and Grimaud, J. A. (1995) Biochem. J. 310 (Part 2), 497−505], this raises the question of the complexe organization. We combine analytical ultracentrifugation, size exclusion chromatography, and hydrodynamic bead modeling to characterize the complexes formed in solution with heparin oligosaccharides. For oligosaccharides of 14 and 20 nm, two types of complexes are formed with one IFN-γ and one or two heparin molecules. Complexes consisting of two IFN-γ and one or two heparin molecules are present for a fragment of 25 nm and aggregates for a fragment of 35 nm. The complexes are rather compact and can be formed without major conformational changes of the partners. The complex pattern of interaction is related to the size of the partners and their multiple binding possibilities. These various possibilities suggest networks of interactions at the crowded surface of the cells. Hydrodynamic methods used here proved to be very efficient tools for describing protein−HS complexes that, due to the intrinsic heterogeneity and flexibility of the partners, are otherwise very difficult to analyze.
  10/2006;
• Article: Conformation of heparin studied with macromolecular hydrodynamic methods and X-ray scattering.

  Georges Pavlov, Stéphanie Finet, Karine Tatarenko, Evgueniya Korneeva, Christine Ebel
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  ABSTRACT: The hydrodynamic characteristics of heparin fractions in a 0.2 M NaCl solution have been determined. Experimental values varied over the following ranges: the sedimentation coefficient (at 20.0 degrees C), 1.3<s0x10(13)<3.2 s; the Gralen coefficient (sedimentation concentration-dependence parameter), 10<ks<70 cm3 g(-1); the translational diffusion coefficient, 3.9< D0x10(7)<15.4 cm2 s(-1); the intrinsic viscosity, 7.9<[eta]<40 cm3 g(-1). Combination of s0 with D0 using the Svedberg equation yielded molecular weights in the range 3.9<Mx10(-3)<37 g mol(-1). The value of the mass per unit length of the heparin molecule, ML, was determined using the theory of hydrodynamic properties of a weakly bending rod, giving ML=570 +/- 50 g nm(-1) mol(-1). The equilibrium rigidity, Kuhn segment length (A=9 +/- 2 nm) and hydrodynamic diameter (d=0.9 +/- 0.1 nm) of heparin were evaluated on the basis of the worm-like coil theory without the excluded volume effect, using the combination of hydrodynamic data obtained from fractions of different sizes. Small-angle X-ray scattering for three heparin fractions allowed an estimate for the cross-sectional radius of gyration as 0.43 nm; from the evolution with the macromolecule contour length of the radius of gyration, a value for the Kuhn segment length of 9 +/- 1 nm was obtained. A good correlation is thus observed for the conformational parameters of heparin from hydrodynamic and X-ray scattering data. These values describe heparin as a semi-rigid polymer, with an equilibrium rigidity that is essentially determined by a structural component, the electrostatic contribution being negligible in 0.2 M NaCl.
  European Biophysics Journal 09/2003; 32(5):437-49. · 2.14 Impact Factor