Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: photon correlation spectroscopy

Sortuj według:

Ogranicz wyniki do:

The effect of mono- and divalent cations on Tetrahymena thermophila telomeric repeat fragment. A photon correlation spectroscopy study

100%

Wlodarczyk A., Patkowski A., Grzybowski P., Dobek A.

Acta Biochimica Polonica

2004

tom 51

nr 4

The structure of the Tetrahymena thermophila telomeric sequence d(TGGGGT)4 was studied by photon correlation spectroscopy (PCS) in aqueous solution in the presence of NaCl, KCl and SrCl2. The sample studied was polydisperse in all conditions studied. Translational diffusion coefficients DT describing the diffusion modes observed were determined. On the basis of a comparison between the experimental DT values with those calculated assuming the bead model, two forms were identified as telomeric quadruplex structures: monomer and tetramer. In the presence of SrCl2 formation of aggregates was observed, with a size that reached several micrometres. The relative weighted concentrations of the structures observed for different concentrations of a salt and DNA were determined. The results obtained in the presence of monovalent ions were qualitatively similar and could be presented in a coherent plot in which the concentration of salt was expressed by the number of ions per DNA molecule. A large number of ions per DNA molecule favoured tetramer formation while a small number favoured the monomer form. A structural phase transition from the monomer to the tetramer induced by a change in the number of ions per DNA molecule was observed. The main difference between the results for Na+ and K+ was a greater effectiveness of the K+ ions in formation of tetramers. The effect of Sr2+ ions on the structures formed was different than that of the monovalent ions. The results obtained in the presence of Sr2+ could not be described as a function of the number of ions per DNA molecule.

Structural polymorphism of telomeres studied by photon correlation spectroscopy

100%

Wlodarczyk A., Gapinski J., Patkowski A., Dobek A.

Acta Biochimica Polonica

1999

tom 46

nr 3

Photon Correlation Spectroscopy (PCS) was used to study the dynamics and structure of Tetrahymena telomeric sequence d(5'-TGGGGT-3')4. Two different modes were observed, corresponding to the following structures: intermolecular (tetramolecular) G-quadruplex and intramolecular (monomeric) G-quartet. Experimental values of translational diffusion coefficients DT were obtained for each structural form. The value of DT for the monomer equals to 1.4 × 106(cm2/s), while for the tetramolecular structure, to 0.8 × 106(cm2/s). The relative weight concentrations of these two forms were analyzed versus the concentration of NaCl varied from 10 mM to 500 mM. The values of experimentally determined diffusion coefficients were compared with those calculated assuming the "bead model" and with the atomic coordinates from the NMR and X-ray crystallographic data. For both structures the experimental and calculated values of DT were in reasonable agreement. In the entire NaCl concentration range studied, the contribution of the relative weight concentration of the monomeric telomere form changed from 85% for 10 mM NaCl to 60% for 500 mM NaCl.

Ograniczanie wyników

2 Acta Biochimica Polonica

2 Dobek A.

2 Patkowski A.

2 Wlodarczyk A.

1 Gapinski J.

1 Grzybowski P.

1 2004

1 1999

Wyniki wyszukiwania

The effect of mono- and divalent cations on Tetrahymena thermophila telomeric repeat fragment. A photon correlation spectroscopy study

Structural polymorphism of telomeres studied by photon correlation spectroscopy