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1.
Tatiana B. Feldman Oleksandr I. Ivankov Alexander I. Kuklin Tatiana N. Murugova Marina A. Yakovleva Olga A. Smitienko Irina B. Kolchugina Adam Round Valentin I. Gordeliy Alexander V. Belushkin Mikhail A. Ostrovsky 《生物化学与生物物理学报:生物膜》2019,1861(10):183000
The supramolecular organization of the visual pigment rhodopsin in the photoreceptor membrane remains contentious. Specifically, whether this G protein-coupled receptor functions as a monomer or dimer remains unknown, as does the presence or absence of ordered packing of rhodopsin molecules in the photoreceptor membrane. Completely opposite opinions have been expressed on both issues. Herein, using small-angle neutron and X-ray scattering approaches, we performed a comparative analysis of the structural characteristics of the photoreceptor membrane samples in buffer, both in the outer segment of photoreceptor cells, and in the free photoreceptor disks. The average distance between the centers of two neighboring rhodopsin molecules was found to be ~5.8 nm in both cases. The results indicate an unusually high packing density of rhodopsin molecules in the photoreceptor membrane, but molecules appear to be randomly distributed in the membrane without any regular ordering. 相似文献
2.
This paper presents a new method for calculating the folding-unfolding rates of globular proteins. The method is based on solution of kinetic equations for a network of folding-unfolding pathways of the proteins. The rates are calculated in the point of thermodynamic equilibrium between the native and completely unfolded states. The method has been applied to all the proteins listed by Jackson [Jackson, S. E. (1998) Folding Des. 3, R81-R91] and some peptides. Although the studied protein chains differ by more than 1 order of magnitude in size and exhibit two- as well as three-state kinetics in water, and their folding rates cover more than 11 orders of magnitude, the theoretical estimates are reasonable close to the experimentally measured folding rates in midtransition (the correlation coefficient being as high as 0.78). This means that the presented theory (having no adjustable parameters at all) is consistent with the experimental observations. 相似文献
3.
T. B. Feldman O. I. Ivankov T. N. Murugova A. I. Kuklin P. V. Shelyakin M. A. Yakovleva V. I. Gordeliy A. V. Belushkin M. A. Ostrovsky 《Doklady. Biochemistry and biophysics》2015,465(1):420-423
Supramolecular organization of rhodopsin in the photoreceptor membrane was investigated by small-angle neutron scattering method. The experiments, which were performed with mixtures of heavy/light water as solvent (contrast variation method), were aimed at obtaining information about the lipid and protein components of the photoreceptor disc membrane separately. It was shown that the packaging density of the rhodopsin molecules in the photoreceptor membrane was unusually high: the distance between the centers of the molecules was approximately 56 Å. The probability of the monomeric state of rhodopsin molecules in the photoreceptor membrane, according to the data obtained, is rather high. 相似文献
4.
Alexey S Kondrashov Inna S Povolotskaya Dmitry N Ivankov Fyodor A Kondrashov 《Biology direct》2010,5(1):5
Background
Divergence of two independently evolving sequences that originated from a common ancestor can be described by two parameters, the asymptotic level of divergence E and the rate r at which this level of divergence is approached. Constant negative selection impedes allele replacements and, therefore, is routinely assumed to decelerate sequence divergence. However, its impact on E and on r has not been formally investigated. 相似文献5.
6.
A study of bacterial surface oligosaccharides were investigated among
different strains of Neisseria gonorrhoeae to correlate structural features
essential for binding to the MAb 2C7. This epitope is widely expressed and
conserved in gonococcal isolates, characteristics essential to an effective
candidate vaccine antigen. Sample lipooligosaccharides (LOS), was prepared
by a modification of the hot phenol-water method from which de-O-acetylated
LOS and oligosaccharide (OS) components were analyzed by ES-MS-CID-MS and
ES-MSnin a triple quadrupole and an ion trap mass spectrometer,
respectively. Previously documented natural heterogeneity was apparent from
both LOS and OS preparations which was admixed with fragments induced by
hydrazine and mild acid treatment. Natural heterogeneity was limited to
phosphorylation and antenni extensions to the alpha-chain. Mild acid
hydrolysis to release OS also hydrolyzed the beta(1-->6) glycosidic
linkage of lipid A. OS structures were determined by collisional and
resonance excitation combined with MS and multistep MSn which provided
sequence information from both neutral loss, and nonreducing terminal
fragments. A comparison of OS structures, with earlier knowledge of MAb
binding, enzyme treatment, and partial acid hydrolysis indicates a generic
overlapping domain for 2C7 binding. Reoccurring structural features include
a Hepalpha(1-->3)Hepbeta(1-->5)KDO trisaccharide core branched on the
nonreducing terminus (Hep-2) with an alpha(1-->2) linked GlcNAc
(gamma-chain), and an alpha-linked lactose (beta-chain) residue. From the
central heptose (Hep-1), a beta(1-->4) linked lactose (alpha-chain),
moiety is required although extensions to this residue appear unnecessary.
相似文献
7.
V. N. Ivankov 《Russian Journal of Marine Biology》2000,26(1):76-78
8.
V. N. Ivankov V. A. Kaplunenko E. E. Borisovets 《Russian Journal of Marine Biology》2016,42(5):402-408
An analysis of the structure of scales from two morphologically close species of Far Eastern redfins, genus Tribolodon, has shown that their species affiliation can be diagnosed not only in adults, but also in immature individuals. The most pronounced inter-species differences between redfins have been observed using a combination of three basic parameters of scales from fish with different body sizes: the lesser diameter, greater diameter, and the number of radii. Since the scale parameters exhibit a non-linear relationship with the body size, the basic parameters were logarithmically transformed for the analysis. 相似文献
9.
When a protein folds or unfolds, it passes through many half-folded microstates. Only a few of them can accumulate and be seen experimentally, and this happens only when the folding (or unfolding) occurs far from the point of thermodynamic equilibrium between the native and denatured states. The universal features of folding, though, are observed in the vicinity of the equilibrium point. Here the two-state transition proceeds without any accumulation of metastable intermediates, and only the transition state (folding nucleus) is outlined by its key influence on the folding/unfolding kinetics. This review covers recent experimental and theoretical studies of folding nuclei. 相似文献
10.
A specimen of the blackfin flounder Glyptocephalus stelleri showing a reversal of the body sides was found for the first time. Records of flounders of the genus Pseudopleuronectes with abnormal body coloration are given. The occurrence of pigmentation on both sides of the body and the reversal of sides are indicative of the manifestation of atavism in flatfishes. The high variability of phenotypic characters, which is common to some species of flatfish with clinal variations, is illustrated using the example of the marbled flounder. 相似文献