Biomedical subjects

G Kh Bozhko

Publications and source records attributed to G Kh Bozhko.

4 recordsLinked to original sources

PubMedDate not supplied

[Melting of DNA-total histone complexes in the presence of noradrenaline].

Study is presented of the effect of noradrenaline on thermic denaturation of DNA-total histone complexes within the range of protein concentrations which corresponds to c1/c2 0-1.7 in solutions of 10(-3) M Na+ ionic strength (c1 and c2 being the weight concentrations of protein and nucleic acid, respectively). Denaturation of these systems has been found to be strongly affected by bivalent metals contained in DNA samples. Their presence accounts for the high temperature and wide melting range of DNA and diminution of the latter with an increase of the protein concentration in DNA-histone complexes. The denaturation parametres obtained for the studied systems are in fair agreement with predictions from the clip thermodynamic theory. Noradrenaline is shown to be capable of destabilizing DNA-total histon complexes. This is due to the inactivation of bivalent metals bound with DNA by noradrenaline. It is also suggested that noradrenaline does not weaken the histone binding with a nucleic acid.

Cations, Divalent↗

PubMedDate not supplied

[Histone-nonhistone protein complex reconstruction].

A complex of chromatin proteins composed of five histon fractions and nine nonhiston fractions and stable in 2M NaCl solution was destructed by treating with urea, changing pH and decreasing the NaCl concentration, No reconstruction of the complex was observed after the said factors has been removed and the initial solvent composition restored. Nevertheless the reconstruction was detected after dissociation of the complex by desalting in the presence of DNA. The reconstruction was successful when stimulated both dimers and tetramers, the chromatin protein complex under study cannot be reconstructed by "self-organization", the only way being through the stage of nucleoproteid formation, and is similar in this respect to some other complex protein structures of the cell.

Animals↗

PubMedDate not supplied

[Studies of histone-nonhistone complex].

A chromatin protein complex was isolated from the calf thymus using hydroxyapatite without denaturants. Polyacrylamide gel electrophoresis showed that this complex consisted of five histones and nonhistone proteins. The complex is stable in 2 M sodium chloride. As the evidence of its stability the results are presented or rechromatography on hydroxyapatite, of gel-filtration on Sephadex G-150 and of polyacrylamide gel electrophoresis after crosslinking proteins by formaldehyde under mild conditions. It is suggested, that hydrophobic interactions which take place under high ionic strength due to the counteraction of protein charged groups, are among the possible mechanisms. This is supported by partial dissociation of the complex with a decrease in the sodium chloride concentrations in the solution.

Animals↗

PubMedDate not supplied

[Studies of DNP protein dissociation in the presence of norepinephrine].

Calf thymus DNP dissociation was studied by sepharose 2B gel-chromatography as well as by oxyapatite ion-exchange chromatography. The degree of dissociation was estimated by protein content in the chromatography peaks. Intact DNP and DNP incubated with norepinephrine were filtered simultaneously through two identical columns. In the presence of norepinephrine a partial deproteinization was observed. This effect has some specificity, namely, it was considerably lower in the presence of tyrosine, and was absent when the norepinephrine structure was changed. On the basis of the available data on the norepinephrine ability to form chelatic complexes with polyvalent metals and comparing the deproteinizing effect of norepinephrine and EDTA it was assumed that the norepinephrine dissociating effect was due to its binding with cations incorporated into the DNP complex structure.

Animals↗