[A study of protein structure changes during hydration by means of diffuse X-ray scattering. II. Fourier transform analysis of X-ray scattering data].

Radial distribution functions were deduced by Fourier transform analysis of angular dependences of diffuse x-ray scattering intensities for the following proteins with different hydration degree: water-soluble a-protein myoglobin, water-soluble alpha+beta protein lysozyme, and transmembrane proteins of photosynthetic reaction centers from purple bacteria Rhodobacter sphaeroides and Blastochlorii viridis. The results of Fourier analysis of x-ray scattering intensities give the quantitative characteristics of the mechanisms underlying the influence of water on the formation of biomacromolecules. Water, on the one hand, weakens the intraglobular hydrogen bond net, loosens the protein structure, and increases the internal conformational dynamics.

[A study of protein structure changes during hydration by diffuse X-ray scattering. I. The intensity and the shape of "10-angstrom" maximum].

The angle dependencies of diffuse x-ray scattering intensities were studied in a wide range of angles from 3 to 80 degrees for water-soluble and membrane proteins with a different structural organization: alpha-helical protein myoglobin, alpha-helical protein serum albumen, alpha + beta protein lysozyme, and transmembrane proteins of photosynthetic reaction centers (RC) from purple bacteria Rhodobacter sphaeroides, and Blastochlorii (Rhodopseudomonas) viridis containing cytocrome c, situated out side the membrane, and for H and L+M subunits of membrane protein of reaction center from Rb. sphaeroides for various hydration degrees. The hydration/dehydration process was studied for water-soluble proteins (within hydration range from h = 0.

[Equilibrium fluctuations in myoglobin and lysozyme].

The angular dependencies of inelastic intensities of Rayleigh scattering of Moessbauer radiation were measured for myoglobin and lysozyme (in the hydration range h = 0.05-0.7).

[Effect of disulfide bonds on lysozyme dynamics].

The effect of destruction of disulfide bonds on the dynamics of proteins was studied by an example of lysozyme by the methods of molecular dynamics. In lysozyme, in the absence of disulfide bonds, the characteristic times of motions of secondary structure devices increased 3-7 times, whereas the amplitudes of fluctuations of secondary structure devices practically did not vary. In the absence of S-S-bonds, the volume of the molecule decreased approximately by 2%, primarily due to a "cleft" between the major and the small domains of lysozyme.

[Molecular dynamics of bending fluctuations in the protein secondary structures].

A comparative study of the dynamics of protein secondary structure elements by the example of alpha-helices of myoglobin, barnase, polylysine, and polyglycine and beta-layers of barnase and GFP was carried out by the methods of molecular dynamics. The effective Young's moduli of both free secondary structure elements and those built in the protein globule were determined. A heterogeneity of the elastic properties of the secondary structure elements was found.