[Conformation of the ribosomal protein S1 of Thermus thermophilus in solution under different ionic conditions].

The structure of protein SI of Thermus thermophilus (M = 61 kDa) in solution at low and moderate ionic strengths (0 M and 100 mM NaCl, respectively) has been studied by small-angle X-ray and neutron scattering. It was found that protein S1 has a globular conformation under both ionic conditions. The modelling of different packing of six homologous domains of S1 on the basis of the NMR-resolved structure of one domain showed that the best fit of calculated scattering patterns from such complexes to experimental ones is observed at a compact package of the domains. The calculated value of the radius of gyration of the models is 28-29 angtroms, which is characteristic for globular proteins with a molecular mass of about 60 kDa. It was found that protein S1 has a tendency to form associates, and the type of the associate depends on ionic strength. These associates have, in general, two or three monomers at a moderate ionic strength, while at a low ionic strength the number of monomers exceeds three and they are packed in a compact manner. Strongly elongated associates were observed in neutron experiments at a moderate ionic strength in heavy water. The association of protein molecules was also confirmed by the data of dynamic light scattering. From these data, the translational diffusion coefficient of protein S1 at a moderate ionic strength was calculated to be (D20,w = (2.7 +/- 0.1) x 10(-7)cm2/s). This value is essentially smaller than the expected value (D20,w = (5.8 - 6.0) x 10(-7)cm2/s) for the S1 monomer in the globular conformation, indicating the association of protein molecules under equilibrium conditions.

[Gel filtration of protected synthetic peptides in dimethylformamide]. / Gel'-fil'tratsiia zashchishchennykh sinteticheskikh peptidov v dimetilformamide.

For large water-insoluble protected peptides, a novel method of analytical and preparative size exclusion liquid chromatography on Toyopearl HW-40, HW-50, HW-55, and HW-60 gels was proposed, with DMF as an eluent. The selectivity and molecular mass ranges of these gels were determined for separation of protected peptides in DMF. The molecular mass ranges of Toyopearl HW gels for protected peptides in DMF were found to differ significantly from those for peptides and proteins in aqueous buffer solutions.

[Comparative study of the radiation oxidation and x-ray chemiluminescence of globular proteins]. / Sravnitel'noe issledovanie radiatsionnogo okisleniia i rentgenokhemiliuminestsentsii nekotorykh globuliarynkh belkov.

Regularities of radiation oxidation (oxygen absorption for irradiation) and X-ray chemoluminescence of human serum albumin solutions have been studied. The oxidative rate was shown to be proportional to chemoluminescence intensity under various experimental conditions. the yield values for radiation oxidation of natural amino acids, glycyl-tryptophane and some other proteins were obtained. These values for amino acids changed in the range of 1.4 to 6, the mean value for amino acid yield was about 3.5 oxygen molecules/100 eV. Protein oxidation yield was in the range of 1.6 to 4. Correlation of the yields with respect to macromolecule spiralization was carried out. The difference in the yields of radiation oxidation protein can be related to higher duration of free radical life-span of amino acid residues forming the spirals that promotes formation of peroxy radicals. The difference of chemoluminescence yields for various proteins can be accounted for by different locations of tryptophan residues accessible for active products of water radiolysis and by the presence of various quantities of arginine in macromolecules. The mechanisms of chemical conversions of tryptophanyl peroxy radicals resulting in the formation of electron-excited states were discussed.

[Retinal sensitized photochemiluminescence of trypsin solutions and the effect of 3-hydroxypyridines]. / Sensibilizirovannaia retinalem fotokhemiliuminestsentsiia rastvorov tripsina i vliianie na nee 3-oksipiridinov.

A study of retinal sensibilized photochemiluminescence of trypsin is carried out. A kinetic scheme of processes responsible for the luminescence appearance according to which chemiluminescence depends on protein groups reaction with singlet oxygen is suggested. The values of a number of kinetic parameters of these processes are determined. The effect of 3-oxypyridine on retinal sensibilized photochemiluminescence is studied. The 3-oxypyridine addition to protein solution with retinal before radiation considerably decreases the intensity and light sum of the luminescence. 2-Oxypyridine photoprotective action is due to their reaction with primary and peroxide radicals of protein. The values of rate constants of interaction of protein radicals with 2,6-dimethyl-3-oxypyridine and 2-ethyl-6-methyl-3-oxypyridine are determined.

[Photochemiluminescence arising during sensitized photooxidation of trypsin solutions]. / Fotokhemiliuminestsentsiia, voznikaiushchaia pri sensibilizirovannom fotookislenii rastovorov tripsina.

Kinetic study of eosin-sensitized photochemoluminescence (PCL) in tripsin solutions was carried out. Kinetics of luminescence increase and decrease, connection between sensitized PCL with triptophane photodissociation in protein were investigated. Effect of the concentrations of protein and oxygen in solution on the parameters of eosin-sensitized PCL was studied in order to establish the succession of processes resulting in the formation of free radicals. The experimental data made it possible to propose a scheme of primary processes responsible for PCL, which shows that the formation of protein radicals proceeded in the reactions between the triplet excited states of dye and singlet oxygen and protein triptophyle residues. It was found that during the formation of radicals in the air at small concentrations of proteins singlet oxygen played a major role in the sensitized photooxidation of protein. It was shown that the mechanism of processes responsible for sensitized PCL, determining postluminescence is similar to tripsin chemoluminescence under UV-illumination. Some kinetic parameters of the processes proceeding during sensitized photooxidation were determined and estimated.

[Photooxidation and photochemiluminescence of different proteins]. / Fotookislenie i fotokhemiliuminestsentsiia razlichnykh belkov.

Information has been obtained concerning photooxidation rate of 18 proteins, blood plasma, glycyl triptophane and some amino acids under UV-irradiation. It has been shown that the majority of the objects studied have the quantum yields of oxygen absorption in the range 0.2--0.6%. Photochemoluminescence of proteins was also investigated. It has been found that protein photochemoluminescence characteristics differ significantly, their main differences are concerned with intramolecular reaction of peroxide free radicals responsible for chemoluminescence with protein acceptors.