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Query: UNIPROT:P06889 (Mol)
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Conditions of formation of the DNA optically-active compact particles (e. g. particles which are characterized by intense negative band in CD spectrum) in PEG-containing solutions of NaCl, NaClO4, KCl, KBr, KI and CsCL have been studied. It has been shown that the region of existence of the DNA optically-active compact particles is restricted not only by the definite concentration of PEG, but also by the definite ionic strength of solution. Above this region the intense band in CD spectra of the DNA compact particles is practically absent. The nature of cation influences the process of compactization (condensation) of the DNA double-stranded molecules; the nature of anion does not influence this process (up to 0,3 M salt concentration).
Mol Biol (Mosk)
PMID:[Conditions of formation of DNA optically-active particles in polyethyleneglycol-containing solutions of different salts]. 47 Sep 38

Different physico-chemical methods (CD, ORD, small-angle X-ray diffraction, etc) were used for investigating the properties of the DNA compact particles formed in PEG-containing water-salt solutions. It has been shown that small-angle reflection, characteristic of the DNA compact particles, changes from 36.8 A (CPEG = 140 mg/ml) to 25 A (CPEG = 300 mg/ml). The maximal optical activity (the intense negative CD-band and optical rotation [alpha] = 60 000 degrees) are inherent properties of the DNA compact particles formed at CPEG 120--180 mg/ml. The high optical activity points to the twist of DNA chromophores through the DNA molecule resulting in a long-rang pitch (P approximately 2000A). Such macroscopic superhelical structure (diameter 40--30 A) is due to conformational distortion of the DNA double-helix with alternating "left" and "right" orientation of chromophoes. Disappearance of conformation distortion is accompanied by disappearance of the high optical activity of the DNA compact particles and results in a small-angle reflection of 25 A. Taking into account the reasons of formation of the optically-active DNA compact particles conditions are suggested to conserve high optical activity at CPEG equal to 400 mg/ml.
Mol Biol (Mosk)
PMID:[Correlation between conformation distortion of the DNA sugar-phosphate backbone and high optical activity of its compact form]. 50 60

Crystals of human oxyhaemoglobin were obtained from poly(ethylene glycol) solutions. Spectroscopic and spectrophotometric measurements on the solutions during crystallization and on the dissolved crystals indicate that the method yields stable crystals of oxyhaemoglobin. Preliminary X-ray studies showed that the crystals obtained are isomorphous with those of deoxyhaemoglobin obtained from poly(ethylene glycol) solutions [Ward, Wishner, Lattman & Love (1975) J. Mol. Biol. 98, 161-177].
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PMID:Crystallization of human oxyhaemoglobin from poly(ethylene glycol) solutions. 64 22

The interaction between various fractions of neurospecific S-100 protein and calcium was studied by means of differential spectrophotometry. Fractions demonstrating "blue" and "red" shifts of the spectrum were detected. The change of conformation, occurring when calcium is bound, results in a redistribution of the protein in the double-phase system (polyetylenglycol-dextran), and the fractions, demonstrating the "blue" shift are transferred to the more hydrophobic phase (PEG), while fractions with the "red" shift move to the less hydrophobic phase (dextran). The existence of fractions with different reaction to calcium binding is discussed considering their participation in controling ionic permeability of neuronal membranes.
Mol Biol (Mosk)
PMID:[Reaction between calcium and different protein S-100 fractions]. 65 77

The formation of compact particles from synthetic double- and triplestranded polynucleotides in water-salt solutions, containing poly(ethylene glycol) (PEG) has been investigated. CD spectra of compact particles are characterized by intense bands (positive or negative) in the region of 270 nm, compact particles being divided into two families--psi- and psi+--according to the CD band sign. The amplitude of the CD band at 270 nm increases with the increase of CPEG. Heating of a solution, containing compact particles, results in a disappearance of the CD band, the "melting" of compact particles as revealed by the CD method occuring prior to the melting of the secondary structure of the corresponding polynucleotide. It is concluded that intense CD bands, which are characteristic of the compact form of synthetic polynucleotides, arise (similar to the case of DNA or dsRNA) from regular arrangement of polynucleotide chains in compact particles. The question, concerning the relation between parameters of the secondary structure of polynucleotides and their belonging either to psi- or to psi+ family is discussed. The factors, which could account for the appearance of intense bands in CD spectra of compact particles are also considered.
Mol Biol (Mosk)
PMID:[Compact form of synthetic polynucleotides. Relationship between secondary structure and circular dichroism spectra]. 65 79

The dependence of viscosity of the water solutions of poly(ethylene glycol) (PEG) on the molecular weight has been studied. It has been shown that there is a "transitional" region in PEG properties which accounts for the formation of fluctuation polymer network of the PEG molecules. It has been shown that the "transitional" region in properties of PEG which appears at a certain concentration of PEG (CtrPEG) is characteristic of the PEG preparations with molecular weights exceeding 600 and dependence of the value of CtrPEG on the molecular weight of PEG was obtained. Compactization of double-stranded DNA molecules in PEG-containing water-salt solutions has been studied and the dependence of the value of CcrPEG, . i.e. the concentration of PEG at which the compact particles of DNA appear in the solution, on the molecular weight of PEG was obtained. The correlation between these two dependences reflecting quite different physico-chemical processes shows that the double-stranded DNA molecules are constrained within the polymer network of the PEG molecules. The influence of ionic strength and ionic composition of the solution on the formation of a compact form was investigated. The transition of the DNA molecules from a linear to a compact state may occur only at a definite value of ionic strength of the solution. This transition may occur at the change of K+ for Na+ cations (at a constant value of CPEG). The extent of compactization of the DNA molecules in PEG-containing water-salt solutions is monitored by the molecular structure and by the ionic strength of the solvent. It is supposed that the peculiarities of compactization of the DNA molecules in PEG-containing water-salt solutions reflect some characteristics of conformational transitions of the DNA molecules which occur in vivo.
Mol Biol (Mosk)
PMID:[Relationship between the molecular structure of aqueous solutions of polyethylene glycol and the compactness of double-stranded DNA molecules]. 66 17

Numerous recombinants arose when protoplasts of S. coelicolor were treated with polyethylene glycol and regenerated on non-selective solid medium. In six-factor crosses, recombination frequencies of more than 10% (up to 17%) were routinely observed. This recombination did not require either of the known sex factors, SCPI and SCP2. The proportion of multiple crossover classes was much higher than amongst recombinants produced by conjugated between mycelia. Analysis of the spatial distribution of crossovers in double and quadruple crossover recombinants showed only a slight tendency for crossovers to occur closer together than randomly on the complete linkage group. This suggests that genomes brought together by protoplast fusion are complete, or nearly so (in conjugation, in contrast, one genome is represented by a comparatively short fragment). Individual colonies arising from fused protoplasts did not contain different parental genomes without recombinants, but recombinants often occurred without parentals. Several recombinant genotypes often occurred in the same colony, showing a segregation of some, only, of the parental alleles. Complementary genotypes, parental or recombinant, did not occur in the same colony. It is postulated that complete genomes of fused protoplasts usually become fragmented and that crossing-over, often repeated, occurs between the fragments, to generate haploid recombinants. Analysis of fusions between propoplasts of four different genotypes indicated that the average number of protoplasts fusing together was low, but nevertheless appreciable numbers of fusions involved three or four genomes. Crossing-over between them produced recombinants inheriting markers from three or four parents. The generation of nearly random populations of recombinants between two or more parent strains by propoplast fusion under the conditions described appears to have simple applications in industrial and academic strain construction.
Mol Gen Genet 1978 Jul 04
PMID:Bacterial protoplast fusion: recombination in fused protoplasts of Streptomyces coelicolor. 68 71

The experimental data indicating that the amplitude of the negative band in CD spectra of DNA compact particles forming in PEG-containing water-salt solutions intensifies with the decrease of DNA molecular weight are presented. This effect is not explained by the light scattering on the compact particles. The presence of the negative band in CD spectrum of DNA compact particles is interpreted as result of formation of dichrographic-active "microcrystalline" region ("domains") (if DNA compact particles are formed from double-stranded molecules with unaltered secondary structure); it is also supposed that the number of these regions in the particle and their dichrographic activity doesn't depend on the particles size. This interpretation is in agreement with experimental data on the increase of the number of compact particles with the decrease of DNA molecular weight. Proportionality coefficient in the linear dependence of the amplitude of negative band on the size of DNA compact particles in solution depends apparently on dichrographic activity of "microcrystalline" regions, and this activity is connected with structural peculiarities of initial DNA molecules.
Mol Biol (Mosk)
PMID:[Compact form of DNA in solution. X. Peculiarities of circular dichroism spectra of DNA compact particles forming polyethylene glycol-containing water-salt solutions]. 75 78

A simple procedure for the isolation of animal mitochondrial DNA is described. It includes deproteinization of mitochondrial lysates with phenol, precipitation of total nucleic acids with polyethylene glycol, RNA precipitation by saet and final purification of DNA using gel chromatography on a Sepharose 4B column. MtDNA preparations obtained were free from protein and RNA and were represented predimonantly by the covalently closed molecules. The content of D-looped molecules in these preparations was equal to 45%.
Mol Biol (Mosk)
PMID:[Simple procedure for the isolation of animal mitochondrial deoxyribonucleic acid]. 75 86

Temperature dependences of absorption and CD spectra of DNA compact particles, formed in water-salt solutions in the presence of poly(ethylene glycol) (PEG), have been compared. It has been shown that the disappearance of a specific negative CD band, characteristic of the DNA compact form, occures prior to the destruction of the DNA secondary structure and is not connected with changes of the number or the size of compact particles. The disappearance of this band is believed to reflect the destruction of ordered structure of microcrystalline regions in DNA compact particles. The temperature, at which this "melting" takes place (taum) increases with the rise of PEG concentration, but always remains below the melting temperature of the DNA secondary structure. The thermodynamic parameters, deltaH and deltaS, which characterize the "melting" of the microcrystalline regions in DNA compact particles, were calculated for each CD "melting" curve and were shown in increase, similarly to taum, with the rise of PEG concentration. These data indicate that the regularity of the internal structure of DNA compact particles depends not only on the structural characteristics of the initial DNA, but also on the solvent properties, in particular, on the PEG concentration.
Mol Biol (Mosk)
PMID:[DNA compact form in solution. XI. Melting of the DNA compact state, formed in water-salt solutions, containing poly(ethylene glycol)]. 75 89


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