Collagen-DNA complex.

Previously presented models of collagen-DNA (7) and collagen-siRNA (8) complexes point to a general description of delivery systems and indicate to what specific topology that system should be equipped with to effectively deliver the gene into the living body via in vivo and in vitro injection. We focused our interest on the nature of collagen-DNA complex structure and the molecular and environmental determinants of the self-association processes of collagen with the presence of DNA. In this aspect, the self-association of collagen-DNA complex offers an opportunity to characterize a unique system, which may be related to the general mechanisms of self-association of fiber macromolecules by water bridges.

Pycnometric, viscometric and calorimetric studies of the process to release the double-stranded DNA from the Un bacteriophage.

Knowledge of both the packaging of the linear, double-stranded (ds)DNA in bacteriophages and its subsequent release into the bacterial host is vital to our understanding of phage infection. There is now strong evidence that packaging requires a powerful rotary motor fuelled by ATP. From thermodynamic studies, however, it has been proposed that, at least for those viruses with a contractile tail, the dsDNA ejection from the phage head is a relatively simple physical process that does not require cellular energy and is facilitated by the difference in the conditions of the medium in the environments inside and outside the head.

[Microcalorimetric and electron spin resonance study of the influence of UV radiation on collagen].

It has been shown by microcalorimetry that UV-irradiation cardinally alters the temperature dependence of heat capacity of a collagen solution and decreases the enthalpy of collagen heat denaturation. By using the method of electron spin resonance (ESR), it was found that the primary products of UV-irradiated acid-soluble collagen are the atomic hydrogen and the anion radical of acetic acid. The latter, under the influence of long-wavelength UV light, is transformed into the methyl radical, which interacts with acetic acid to produce acetic acid radical.

Fiber molecular model of atelocollagen-small interfering RNA (siRNA) complex.

Previously we represented molecular model of collagen triple helix-DNA double helix complex [G.M. Mrevlishvili, D.

Biophysics of T5, IRA phages, Escherichia coli outer membrane protein FhuA and T5-FhuA interaction.

In spite of the similarities in a structural organization of T5 and IRA phages their thermal and hydrodynamical peculiarities are completely different. One of the significant differences is observed in temperature value at which thermally induced DNA ejection starts. If in the case of physiological conditions this difference equals to 30 degrees capital ES, Cyrillic, then it decreases as ionic strength of the solvent decreases.

DNA as a matrix of collagen fibrils.

In this paper we demonstrate that DNA binds to collagen directly to form DNA-collagen complex. Our model suggests that DNA, containing well-arranged phosphate groups, helps the collagen to make ordered aggregates-fibrils. During this process hydration shell of collagen triple helix destroys and stabilizes hydration shell of ds-DNA.

Complex between triple helix of collagen and double helix of DNA in aqueous solution.

We demonstrate in this paper that one example of a biologically important and molecular self-assembling complex system is a collagen-DNA ordered aggregate which spontaneously forms in aqueous solutions. Interaction between the collagen and the DNA leads to destruction of the hydration shell of the triple helix and stabilization of the double helix structure. From a molecular biology point of view this nano-scale self-assembling superstructure could increase the stability of DNA against the nucleases during collagen diseases and the growth of collagen fibrills in the presence of DNA.

Hydration of ds-DNA and ss-DNA by neutron quasielastic scattering.

Quasielastic neutron scattering measurements were performed in hydrated samples of ds-DNA and ss-DNA. The samples were hydrated in a high relative humidity atmosphere, and their final water content was 0.559 g H(2)O/g ds-DNA and 0.

[A viscosimetric study of thermally induced release of ds-DNA from Un phage].

The thermally induced ejection of DNA from the head of the Un phage was studied by viscosimetry, pH was used as a variable external factor. The results obtained suggest that the infection of the bacterium by the phage occurs in the pH range 6-10 rather than in the acidic medium (pH 4-5) because the infection can take place only if the DNA is completely ejected from the phage head. It was shown that the ejection of DNA upon dilution of the initial concentration of the phage depends on the time required for the equilibrium of the phage suspension in the corresponding buffer solution to be established after which the measurements can be performed.

Liposome-DNA interaction: microcalorimetric study.

The authors applied differential scanning calorimetry (DSC) for studying the thermodynamic characteristics of DNA-liposome interactions. At the first stage, the melting curves of the 'order-disorder' thermal transition for lipid component and of the 'helix-coil' transition for DNA were obtained. At the second stage, the phase behavior of the DNA-lipid mixture as a function of both components (lipid/DNA ratio) was obtained.

[Denaturation increment of heat capacity in diluted aqueous solutions of collagen].

The experimental values of the denaturation increment of collagen heat capacity in diluted aqueous solutions, obtained at different scanning rates, are presented. It is shown that the dependences of the "equilibrium" enthalpy and entropy of collagen denaturation on denaturation-induced variation in heat capacity do not obey the empiric law of the linear correlation of the thermodynamic parameters of denaturation at 25 degrees C for globular proteins, indicating that the stabilization of the triple collagen helix proceeds by a special mechanism with the participation of water molecules.

[Cu(II) complexes with biomacromolecules. The use of Cu(II) ions as a structural spin label].

Complexes of Cu(II) ions with globular proteins (human serum albumin, bovine serum albumin, egg albumin, lisozim and DNA) have been studied using the ESR method. It was shown that Cu(II) ions may be use as structural "spin-label" to study conformational dynamics of macromolecules, including structural transition in biopolymers.

[Heat capacity of native DNA fibers at 2-25 K].

The data on low-temperature heat capacity (2-25 K) of native DNA strands at different humidities are presented, which take into account the specificity of hydration of DNA due to its chemical composition (GC-content). The temperature dependence of DNA heat capacity (Cp = f(T)) at 2-4 K was analyzed. Analysis of Cp = f(T) involves both the ordinary Debay density and excessive low-energy density of oscillatory states (DOS) peculiar to noncrystalline solids.

[Aperiodic structures, fractals, and low temperature heat capacity of biological macromolecules].

Low-molecular heat capacity of biological macromolecules has been analyzed in terms of modern conceptions of the physics of disordered systems and noncrystalline solids. It is shown that the fundamental thermodynamic features of these systems (amorphous and aperiodic structures, fractals polymers, etc.) are also inherent in biopolymers--proteins and nucleic acids, which gives a better insight into their structural-conformational and dynamic properties.

[Hydration and stability of the B-form of LiDNA].

Hydration and structure of Li DNA in films and solutions have been investigated by methods of IR spectroscopy, piezogravimentry, UHF dielectrometry, and microcalorimetry. The hydration energy and the water sorption range in which the DNA undergoes the transition from the unordered state to the B-form have been determined, making it possible to evaluate the contribution of water molecules of the DNA hydration shell to the total stabilization energy of the DNA helical structure.

[Appearance of fractal properties of globular proteins at low temperatures].

The dependence on temperature of the heat capacity of cytochrome c has been measured in the range 4-40 K at various water content. The fractal (Hausdorff) dimension of the protein (D) has been determined and shown to depend on the rate of protein hydration (1.1 < D < 1.

[Difference in DNA enthalpies in the helical and coiled states near 0 K].

On the basis of experimental data of DNA heat capacity in a wide range of temperatures the fundamental characteristics of DNA-H(0)0-the enthalpy of helix coil transition at 0(0)K were estimated. H(0)0 = 8.41 +/- 1.

[Heat capacity of DNA in native and denatured states].

Heat capacity of DNA in native and denatured states was estimated by the method of microcalorimetry. This value was shown to depend on the transition temperature and is determined by an increase of the number of oscillative freedom degrees of the polynucleotide chains in the state of statistical coils, and by hydrophobic effects and by "the melting of water ridge" located in native DNA in the B-form.

[A theoretical model of DNA packaging in the phage head].

Statistical model of dsDNA packaging to icosahedral bacteriophage capsid is presented. The model describes intraphage DNA as a globule, i.e.

[Calorimetric study of aqueous solutions of histone H1 and poly-L-proline II at low temperatures].

Low temperature differential scanning microcalorimetric investigation of water-histone H1 and water-poly-L-proline investigation was carried out. The concentrational dependence of the thermodynamic parameters (delta H(C), Tmax(C), delta S(T, C] for "bulk" water layers were studied. It was shown that the influence of these macromolecules on the structure and properties of surrounding water layers at the same degree of hydration is different.

[Energy of cooperative transitions in bacteriophage SD].

Heat denaturation of native phages SD suspensions, phage "shadows", and isolated phage DNA solutions were studied by scanning microcalorimetry and viscosimetry. Energetic parameters of cooperative transitions of protein fraction and DNA were measured. DNA melting was shown to be preceded by the destruction of capsid and protein denaturation.

[Low-temperature heat capacity of DNA in various conformation states].

Experimental results are presented on temperature--dependent DNA heat capacity in three different states: a) intact--native DNA in the conformation of double helix, b) disordered conformation of polynucleotide chains in the state of statistical coils, c) completely "degenerated" polynucleotide chains--mechanical mixture of nucleotides. Data on heat capacity (4-400 K) at different water content in the specimens allow a definition of relative changes in the pattern of the entropy temperature dependence for these conformational states with the account for the structural effect of water.

[Study of dynamic properties of water in poly(A) and poly(U) solutions by proton magnetic resonance].

Proton magnetic relaxation in aqueous solutions of polyadenylic and polyuridylic acids in the temperature range (10-80 degrees C) and acidities (pH 3-9.7) has been investigated. Activation energies of water molecule diffusion and proton exchange, as well as the velocities of these processes have been determined.