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At least 325 records · Page 18Linked to original sources
PubMed1991

[The spatial structure and hierarchy of the ecological groups in the skin microbiocenosis of the breasts].

In 120 nulligravidae, 175 pregnant women and 280 puerperants the skin microbiocenosis of mammary glands was studied. Its horizontal structure, the types of the distribution of different ecological groups over the surface of the biotope and their hierarchy, as well as the diversity of species at different anatomical areas, were described. The study showed that the representatives of resident flora were characterized by group distribution, while for transitory flora variations from occasional distribution in nulligravidae to group distribution in nursing mothers were noted. The most pronounced changes in hierarchy were observed in puerperants. In nursing mothers a significant increase in the diversity of species at different anatomical areas were also disclosed.

Adolescent↗
PubMed1991

[Spatial structure of the basic chain of the neurotoxin I molecule from the venom of cobra Naja naja oxiana and its crystal packing].

The structure of the alpha-carbon chain was solved by molecular replacement method at 2.7 A resolution. Neurotoxin I (NTX-I) is one of the main protein components purified from the venom of the central asian cobra Naja naja oxiana. NTX-I is known to bind specifically to acetylcholine receptors thus preventing the transmission of the neuroconductivity signal from synapses to muscles. NTX-I crystals were grown either by vapour diffusion or dialysis methods using specially prepared microdialysis cell. The intensities of reflections from native NTX-I crystals were measured in the range of 38.0-2.1 A-1 by omega-scan method with a Syntex P21 diffractometer operated in automatic regime. To determine the position and mode of packing of NTX-I molecule in unit cell program packages MERLOT and BLANC were applied running on a NORD-500 computer.

Amino Acid Sequence↗
PubMed1990

[Study of the spatial structure of the duplex d(pTGTTTGGC) d(pCCAAAC)A in aqueous solution by methods of uni- and two-dimensional (1)H-NMR spectroscopy and organic molecular mechanics].

Structure of the complementary complex d(pTGTTTGGC) d(pCCAAAC)A in the aqueous solution has been investigated by one- and two-dimensional 1H NMR spectroscopy. The resonances of nonexchangeable protons of bases as well as methyl and deoxyribose 1', 2'a, 2'b, 3' and 4' protons have been assigned by means of two-dimensional J-correlated spectroscopy (COSY) and two-dimensional nuclear Overhauser enhancement spectroscopy (NOESY). Using one-dimensional NOE measurements, 62 interproton distances (intranucleotide: (H6/H8)i--(H1')t, (H6/H8)i--(H2'a)i, (H1')i--(H2'a)i, (H1')i--(H2'b)i; internucleotide: (H6/H8)i--(H1')i-1, (H6/H8)i--(H2'a)i-1, (H6/H8)i--(H2'b)i-1, (H5/CH3)i--(H6/H8)i-1, (H5/CH3)i--(H2'a/H2'b)i-1) have been determined for nearest-neighbour protons. Spin-coupling constant values for some sugar protons have been obtained from COSY spectra. The restrained molecular mechanics calculations have yielded the possible solution structures of duplex fitting the experimental set of interproton distances and coupling constants.

Base Sequence↗
PubMedDate not supplied

[Various views on the formation of the spatial structure of proteins].

Basing on the protein tertiary structure data analysis, the peculiarities of enzymatic catalysis, as well as on the results of ab initio conformational energy map calculations of dipeptides, the conclusion is drawn, that the synthesis of polypeptide chains on the ribosome occurs on the right hand conformation of amino acid residues. For the number of amino acid residues to transfer to left hand conformation, local and electoral conditions are necessary. Some possible errors in the X-ray crystal structure data of proteins are pointed out.

Amino Acids↗
PubMedDate not supplied

[Computer analysis of the spatial structure of the amphotericin channel].

Energy of Amphotericin B cholesterol complex in a membrane was calculated by the method of atom--atomic potentials. The complex is shown to have two stable states. One of them is stabilized by electrostatic interactions between charged groups of neighbouring antibiotic molecules due to a decline of the molecules to the pore radius. Another state with radial orientation of antibiotic molecules and smaller pore diameter is stabilized mainly by van-der-Waals forces. A conclusion is made that transitions between open and closed states may result from small shifts and turn of all the antibiotic molecules in the complex.

Amphotericin B↗
PubMedDate not supplied

[The spatial structure and interrelation of plerocercoids of Digramma interrupta (Cestoda, Ligulidae) and the bream (Abramis brama) in the Kuibyshev reservoir].

The character of the distribution of the plerocercoid D. interrupta in the bream Abramis brama from the Kuibyshev water reservoir was studied. The spread of the parasites in A. brama population is of complex character and changes with the increase of fish body length. The factors affecting the maintenance and regulation of the relationships in the host-parasite system (size composition of fishes, peculiarities of the host's genotype, values of occurrence of different numbers of the parasites, variability of plerocercoids) are discussed.

Animals↗
PubMedDate not supplied

[Spatial structure of secretin molecule].

By conformational analysis and circular dichroism the structure of peptide hormone secretin and its shortened N-terminal fragments in different solvents (water, aqueous solutions of alpha-L-phosphatidic acid and sodium dodecyl sulfate) have been studied. The results obtained by the two methods are compared.

Circular Dichroism↗
PubMedDate not supplied

[Spatial structure of the cro-repressor in a solution. I. Identification of interaction in a hydrophobic cluster using the nuclear Overhauser effect].

The structure of a bacteriophage lambda cro repressor hydrophobic globule was studied by the technique of 1H NMR spectroscopy at 500 MHz. The analysis of NOE difference spectra and building of the molecular models for the most probable fragments of the secondary structure allowed us to assign many signals in the protein spectrum and to identify the intramolecular interactions which stabilized the hydrophobic globule and the tertiary structure of the molecule. The results suggest that the structure of the cro repressor hydrophobic globule in solution coincides with the crystal one, although there are some differences in the mutual arrangement of the alpha 1 helix and the three-fold beta-sheet. Resonance assignment has made it possible to study conformational changes and specific interactions of the cro repressor by using suitable reporter groups.

Bacteriophage lambda↗
PubMed1978

[Chemical modification of epsilon-amino lysine groups in horseradish peroxidase. Its effect on catalytic properties and spatial structure of the enzyme].

Effect of chemical modification of horseradish peroxidase lysine epsilon-amino groups by propionic, butyric, valeric, succinic anhydrides and trinitrobenzolsulfonic acid (TNBS) on catalytic properties of the enzyme is investigated. All the preparations of modified peroxidase have 100% peroxidase activity for o-dianizidine at pH 7.0, which indicates the absence of lysine epsilon-amino group in the enzyme active site. pH-dependencies of modified peroxidase relative activity are studied; modification by anhydrides of monobasic acids is not found to result in changes of the relative activity pH-profile, while modification by succinic anhydride widens it. Absorption and circular dichoism spectra of native and modified peroxidase within 260--270 nm are obtained, some changes in the enzyme tertiary structure after its epsilon-amino groups modification are observed. Modification of four epsilon-amino groups by buturic and succinic anhydrides and of three epsilon-amino groups by TNBS is found to increase the regidity of protein surrounding of heme, and modification of six epsilon-amino groups by TNBS results in more unwrapped enzyme structure as compared with its native molecule.

Butyrates↗
PubMed1986

[Determination of phosphate residues participating in the formation of the spatial structure of tRNA- Leu IAG from cow mammary glands].

The phosphates of the tRNA-Leu IAG from cow mammary gland (tRNA which has a long variable loop) participating in the formation of three-dimensional structure were studied by alkylation with ethylnitrosourea and methylnitrosourea. A low degree of modification was observed for the phosphates of the following nucleotides: 7, 8, 9, 10 (at the bend site between the acceptor and D-stem); 18, 19, 20A and 21 in the D-loop; 47H and 49 at the joint of variable and T-stem; 57, 58 and 59 in the T-loop.

Animals↗