Biomedical subjects
Publications and source records attributed to V G Budker.
Interaction of DNA with planar bilayer phosphatidylcholine membrane in the presence of CaCl2 increases electric conductance of the membrane several times as a result of the formation of DNA-membrane complex. The same effect was observed in the cases of ribosomal RNA and synthetic homopolymers polyA, polyU and polyA X polyU double helix.
It was shown that a change in conductance and capacitance of BLM can be explained by Ca++ BLM--heparin complex organization.
The temperature dependence of poly(C) is shown by the infrared spectroscopy to be different for the free polynucleotide and for the polynucleotide in complexes with membranes. The intensity of stretching vibrations of C = 0 bond of poly(C) in the complex appears to be sensitive to the temperature. The intensity of this band is sharply decreased by increasing the temperature. This effect depends upon concentration of Mg2+-cations. Adsorption of poly(I)-poly(C) on the surface of vesicles from phosphatidylcholine results in the increase of the double helix.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
IR-spectra of poly-A phosphatidylcholine complexes in D2O were studied. It has been shown that in the absence of Mg2+ the spectrum was a superposition of spectra of poly-A and phosphatidylcholine. Introduction of MgCl2 to the concentration of 0.03 M led to the dramatic decrease of absorbance at 1629 cm-1 characteristic of backbone vibration of adenine. Further increase of the concentration of MgCl2 up to 0.08 M resulted in the additional absorbance maximum at 1627 cm-1. Under a variety of temperatures the position of the maximum did not change. It was assumed that on adding magnesium ions to the "poly-A-lipid" mixture in D2O the components formed a stable complex. At high Mg2+ concentration a partial disarrangement of stacking interactions in poly-A occurred that might be a consequence of the incorporation of nucleic bases into hydrophobic membrane phase.
4-(N-2-chloroethyl-N-methylamino)-benzaldehyde acetyl derivatives of penta-., hexa, hepta-, octauridylates were used for localization of the structures organizing the mRNA-binding centre of ribosomes. These derivatives, alike free oligonucleotides, stimulate the binding of phenylalanyl-tRNA to ribosomes. Within the specific complex all the oligonucleotide derivatives alkylated the 30S ribosomal subunit. Octauridylate and hexauridylate derivatives specifically alkylated also the 50S subunit of ribosomes. Polyuridylic acid protected ribosomal subunits from alkylation. In the 30S subunit the derivatives modify 16S RNA and proteins: S4, S5, S7, S9, S13, S15, S18, S21. It was found that oligouridylate derivatives of different length alkylate different proteins.
The possibility of transfection of bacterial cells by phage M13 DNA entrapped into phospholipid vesicles (liposomes) has been studied. Two types of liposomes differing in size were used. Entrapped DNA was transferred by liposomes into Ca2+-treated E. coli cells. Efficiency of the transfection in the case of small (ca. 400 A) liposomes was 2--3 orders of magnitude higher than that of free DNA extracted from such liposomes.
Explore the source record for details and available documents.
4-N-2-chloroethyl-N-methylamino-benzaldehyde acetal derivatives (RCL-derivatives) of octauridylic and nanauridylic acids were used to localize the structures organizing mRNA-binding site of ribosomes. These derivatives, like free oligonucleotides, stimulate binding of 14C-phenylalanyl-tRNA to ribosomes. They effectively alkylate ribosomes within the specific complex. The extent of 30S subunit alkylations is much greater than that of 50S subunit, alkylation being completely inhibited by preincubation with polyridylic acid, suggesting that the chemical alteration occurs near mRNA-binding site. Both rRNA and proteins undergo modification in 30S subunit (75% and 25% of the total 30S subunit modification, respectively).