Anatoly I. Dragan

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Absorption and fluorescence spectra of some tyrosine-containing proteins were analysed. Comparison of the peculiarities of fluorescence and absorption of the tyrosine chromophore in the model compounds and proteins suggested a new classification of the states of tyrosine residues in proteins: I -- tyrosyls with hydrated OH-group (lambda mf approximately(More)
We discuss the effectiveness of existing methods for understanding the forces driving the formation of specific protein-DNA complexes. Theoretical approaches using the Poisson-Boltzmann (PB) equation to analyse interactions between these highly charged macromolecules to form known structures are contrasted with an empirical approach that analyses the(More)
The interaction of the second and third AT-hooks of HMGA1 (formerly HMGI/Y), which bind selectively in the minor groove of an AT-rich DNA sequence, was studied at different temperatures and ionic strengths by spectropolarimetry, spectrofluorimetry, isothermal titration calorimetry and differential scanning calorimetry. The data show that binding of the ten(More)
The capabilities of contemporary differential scanning and isothermal titration microcalorimetry for studying the thermodynamics of protein unfolding/refolding and their association with partners, particularly target DNA duplexes, are considered. It is shown that the predenaturational changes of proteins must not be ignored in studying the thermodynamics of(More)
Homeodomains are helix-turn-helix type DNA-binding domains that exhibit sequence-specific DNA binding by insertion of their "recognition" alpha helices into the major groove and a short N-terminal arm into the adjacent minor groove without inducing substantial distortion of the DNA. The stability and DNA binding of four representatives of this family,(More)
The energetics of the Sox-5 HMG box interaction with DNA duplexes, containing the recognition sequence AACAAT, were studied by fluorescence spectroscopy, isothermal titration calorimetry (ITC) and differential scanning calorimetry (DSC). Fluorescence titration showed that the association constant of this HMG box with the duplexes is of the order 4x10(7)(More)
Temperature-induced reversible unfolding and refolding of the three-stranded alpha-helical coiled coil, Lpp-56, were studied by kinetic and thermodynamic methods, using CD spectroscopy, dynamic light scattering, and scanning calorimetry. It was found that both unfolding and refolding reactions of this protein in neutral solution in the presence of 100 mM(More)
Understanding the forces driving formation of protein/DNA complexes requires measurement of the Gibbs energy of association, DeltaG, and its component enthalpic, DeltaH, and entropic, DeltaS, contributions. Isothermal titration calorimetry provides the enthalpy (heat) of the binding reaction and an estimate of the association constant, if not too high.(More)
The specific association of many DNA-binding proteins with DNA frequently results in significant deformation of the DNA. Protein-induced DNA bends depend on the protein, the DNA sequence, the environmental conditions, and in some cases are very substantial, implying that DNA bending has important functional significance. The precise determination of the DNA(More)
A stepwise replacement of somatic histones on sperm-specific proteins (we have termed them illexines I1 and I2) is found to occur during spermatogenesis of squid Illex argentinus [Kadura, S.N. and Khrapunov, S.N. (1988) Eur. J. Biochem. 175, 603-607]. The chromatin from nuclei of squid immature testes has a nucleosomal DNA repeat which corresponds to the(More)