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11.
The dynamic evolution of the PrP(C) from its NMR-derived conformation to a beta-sheet-rich, aggregation-prone conformation is studied through all-atom, explicit solvent molecular dynamics in different temperature and pH conditions. The trajectories are analyzed by means of a recently introduced energy decomposition approach aimed at identifying the key residues for the stabilization and folding of the protein. It is shown that under native conditions the stabilization energy is concentrated in regions of the helices H1 and H3, whereas under misfolding conditions (low pH, high temperature, or mutations in selected sites) it is spread out over helix H2. Misfolding appears to be a rearrangement of the chain that disrupts most of the native secondary structure of the protein, producing some beta-rich conformations with an energy distribution similar to that of the native state. 相似文献
12.
We examined vertical migration and colonisation patterns of stream macroinvertebrates within the substratum of an Apennine
creek in NW Italy. Macrobenthos was sampled at three depths in the streambed (0–5, 5–10, 10–15 cm) by means of artificial
baskets filled with natural substratum. We placed 42 traps (5×5×15 cm), i.e. 21 top-opened (T-traps) and 21 bottom-opened
(B-traps), each composed of three overlapping baskets (high-H, medium-M and low-L), to evaluate differences in the vertical
movements. We also collected Surber samples to compare interstitial assemblages with streambed communities. The multilevel
traps yielded 42 taxa, compared with 60 taxa in the natural riverbed. Interstitial traps were rapidly colonised; both taxa
richness and organism number increased during the 42-day study period. We found active migration in both vertical directions,
but there were more invertebrates in the top-opened traps than in the bottom-opened traps. In the T-traps the most colonised
baskets were those placed at the H level, while in the B-traps the L level baskets were more rapidly colonised. The interstitial
assemblages differed markedly from the streambed communities in both composition and functional organisation, with more collector-gatherers
and predators in the interstitial zone and more filterers and scrapers in the natural riverbed. In Apennine lotic systems,
the interstitial zone is an important habitat for stream macrobenthos, although it may not be used by all species. 相似文献
13.
Mauro Magnani Vilberto Stocchi Marina Dachà Giorgio Fornaini 《Molecular and cellular biochemistry》1984,61(1):83-92
Summary Rabbit hexokinase (EC 2.7.1.1) has been shown to exist in reticulocytes as two distinct molecular forms, designated hexokinase Ia and Ib, but only one of these was consistently present in mature red cells. In vivo, hexokinase la and Ib show a decay rate of 3 and 8% a day, respectively, while in vitro they show a similar stability.The possibility that the proteolytic activities of the reticulocyte could be responsible for the fast decay of hexokinase was investigated. No differences were found in the decay rates of hexokinase la and Ib during in vitro reticulocyte maturation in presence or absence of proteolytic inhibitors. Contrariwise, many findings indicate the ATP-dependent proteolytic system of the reticulocyte as a possible mechanism. In fact, the decay of hexokinase and the degradation of 3H-globins are both stimulated by ATP and ubiquitin; they show similar kinetic properties and both disappear during reticulocyte maturation.The cellular localization of hexokinase la and Ib was shown to be responsible for the differences found between their decay rates.Abbreviations PMSF
phenylmethylsulfonyl fluoride
- TPCK
1-1-tosylamide-2-phenylethyl-chloromethyl ketone
- TLCK
N -p-tosyl-L-lysine chloromethyl ketone 相似文献
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15.
Sampietro M Bottani CE Carminati M Casari C Castoldi A Ferrari G Fusi M Guazzoni C Rottigni A Vergani M 《IEEE pulse》2011,2(3):35-40
The increase in the understanding of the physical and functional properties of the biological material, from the cellular level down to single molecules, owes its success to the development of suitable high-sensitivity platforms to image the biomaterial and analyze its response to specific stimuli. Imaging has indeed reached molecular capabilities, thanks to optical or magnetic markers [1], to the atomic force microscopy (AFM) in surface reconstruction [2], and is nearing success in three-dimensional (3-D) reconstruction thanks to X-ray holography [3]. 相似文献
16.
Giorgio M Trinei M Migliaccio E Pelicci PG 《Nature reviews. Molecular cell biology》2007,8(9):722-728
The reactive oxygen species that are generated by mitochondrial respiration, including hydrogen peroxide (H2O2), are potent inducers of oxidative damage and mediators of ageing. It is not clear, however, whether oxidative stress is the result of a genetic programme or the by-product of physiological processes. Recent findings demonstrate that a fraction of mitochondrial H2O2, produced by a specialized enzyme as a signalling molecule in the pathway of apoptosis, induces intracellular oxidative stress and accelerates ageing. We propose that genes that control H2O2 production are selected determinants of lifespan. 相似文献
17.
Lan YY Wang Z Raimondi G Wu W Colvin BL de Creus A Thomson AW 《Journal of immunology (Baltimore, Md. : 1950)》2006,177(9):5868-5877
18.
19.
Bisetto E Picotti P Giorgio V Alverdi V Mavelli I Lippe G 《Journal of bioenergetics and biomembranes》2008,40(4):257-267
The role of the integral inner membrane subunit e in self-association of F0F1ATP synthase from bovine heart mitochondria was analyzed by in situ limited proteolysis, blue native PAGE/iterative SDS-PAGE, and LC-MS/MS. Selective degradation of subunit e, without disrupting
membrane integrity or ATPase capacity, altered the oligomeric distribution of F0F1ATP synthase, by eliminating oligomers and reducing dimers in favor of monomers. The stoichiometry of subunit e was determined
by a quantitative MS-based proteomics approach, using synthetic isotope-labelled reference peptides IAQL*EEVK, VYGVGSL*ALYEK,
and ELAEAQEDTIL*K to quantify the b, γ and e subunits, respectively. Accuracy of the method was demonstrated by confirming
the 1:1 stoichiometry of subunits γ and b. Altogether, the results indicate that the integrity of a unique copy of subunit
e is essential for self-association of mammalian F0F1ATP synthase.
Elena Bisetto and Paola Picotti contributed equally to this work. 相似文献
20.
UTRdb and UTRsite: specialized databases of sequences and functional elements of 5′ and 3′ untranslated regions of eukaryotic mRNAs. Update 2002 下载免费PDF全文