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A D Gruzdev

Publications and source records attributed to A D Gruzdev.

46 records · Page 3Linked to original sources
PubMedDate not supplied

[Structure of virions of the M13 phage containing chimeric B-protein molecules].

We have studied the virion structure of M13 strains (M13B1, M13BOM1, M13BOM2, M13BOL1) with chimeric variants of B-protein. Data concerning the spatial structure of chimeric B-protein molecules and their interaction with intraphage DNA were obtained. The phage contour lengths were measured under electron microscope and the DNA/protein ratios were obtained by spectrophotometry. These data testified that the insertion of foreign peptide affected neither DNA packaging nor the compactness of molecular arrangement of proteins in the virion. By linear dichroism and fluorescence spectra of phages it was determined, that the insert can influence the polarity of amino acid environment and the orientation of amino acids in the B-protein central part. It was shown by quenching of phage fluorescence by KI that the inward or outward amino acids location in the capsid is invariable. The carboxyl residues have been titrated in the phage strains by Auramine O. It was shown that there is no correlation between the number of the titrated carboxyl groups and the number of the carboxyl groups as a whole.

Amino Acid Sequence↗
PubMedDate not supplied

[Effect of the length of internucleosome regions of DNA on the conformation of chromatid fibrils].

Models of chromatin fibers structures with linear regions of linker DNA were analysed. Limitations put by end dimensions of linker DNA and nucleosomes are considered. Good agreement between the structural properties of model and real chromatin fibers was obtained. It has been shown that the models with three and more configurations of closely located nucleosomes have linker DNA of 19-53 base pairs length, which is characteristic of real chromatin of the majority of somatic cells.

Chromatin↗
PubMedDate not supplied

[DNA packing in the DNP fibrils of polytene chromosomes].

Isolated polytene chromosomes stained with acridine orange were stretched with micromanipulator needles. Changes of chromosome fluorescence polarization led to the conclusions: 1) almost complete orientation of DNP fibers is attained at very low levels of chromosome stretching (3--8 times) without irreversible disruption of chromomeres; 2) internucleosomal DNA in native DNP fibers is supercoiled and makes 30 degrees angle to the fiber axis.

Acridines↗
PubMedDate not supplied

[Models of chromatin fibril organization].

Idealized models of chromatin fibers are presented. They are based on the data of nucleosome structure and on the postulate about lengths congruence and rectilinearity of internucleosomal DNA fragments. It has been shown that the majority of models are in the form of spirals with the diameter 30--40 nm consisting of chains of successively located nucleosomes. With some lengths of internucleosomal stretches the spirals are transformed to linear columns with two, three of four rows of nucleosomes. The DNA packing coefficient strongly depends on the shape of the model. The structure of real chromatin fibers is believed to be close to that of compact models. Corrections of the models due to supercoiling of internucleosomal DNA stretches are considered qualitatively.

Chromatin↗
PubMedDate not supplied

[Site-specific scission of DNA of polytene chromosomes of Chironomus thummi in situ by the oligoadenylate alkylating derivatives].

The possibility of site-specific scission of DNA in polytene chromosomes in situ by means of the method of complementarily addressed fragmentation is demonstrated. The fragmentation of polytene chromosomes of Chironomus thummi resulting from the alkylation of the denatured chromosomes with oligoadenylate derivatives, followed by scission of the DNA in specific sites and enlargement of nicks with exonucleases was investigated. Single-stranded regions were registered by means of luminescence microscopy after staining the chromosomes with acridine orange. The pattern of degradation of the chromosomes depends on the length of the oligoadenylate part of the reagents and is different from that obtained with uridine-5'-methylphosphate alkylating derivative which does not form any complexes with DNA. Oligoadenylates inhibit the action of the alkylating derivatives on the chromosomes.

Alkylation↗
PubMedDate not supplied

[Relative positions of stainable portions of DNA in deoxyribonucleoprotein fibrils].

The effect of acridine orange (AO) concentration on fluorescence polarization of DNA, DNP100 and DNP250 solutions (100 A and 249 A thick DNP fibers, respectively) was studied. It was shown that fluorescence depolarization by an excitation energy migration mechanisms is 3.5 times more efficient for DNP250 than for DNP100. Higher efficiency of energy migration may be explained by a tighter packing of stained DNA regions inside the 250 A fiber because both DNP100 and DNP250 have equal numbers of AO binding sites. The calculated average number of packed DNA strands in DNP250 is 3, the average angle between them is 26.5 degrees. A model of the 250 A DNP fiber is proposed. In this model nucleosomes form a tight 250 A coil with a 430 A pitch, internucleosomal DNA strands are oriented approximately along the fiber axis.

Acridines↗