Crystalline

In the present paper, we reported the influence of the crystallization time on the crystallinity of the Fe-mordenite zeolite (Fe- MOR). The obtained results showed that, in order to reach the high crystallinity of zeolite the optimal duration of crystallization was about 36 h.

9p 12120609 01-06-2020 5 0   Download

It was demonstrated that Poly(p-Xylylene) (PPX) could be prepared from α,α’-Bis(Alkoxy or Aryloxy) –p-Xylenes via chemical vapor decomposition (CVD)- method. This is one-step process and there are side products by the CVD-process. This effect depends both on the CVD- condition and the properties of the starting monomer. The structure and thermal behavior of the material were characterized by FTIR, UVvis spectroscopy, elemental analysis, wide-angle X-ray diffraction, DTA and DSC.

14p 12120609 01-06-2020 17 1   Download

Starch defines a semicrystalline polymer made of two different polysaccharide fractions. The A- and B-type crystalline lattices define the distinct structures reported in cereal and tuber starches, respectively. Amylopectin, the major fraction of starch, is thought to be chiefly responsible for this semicrystalline organization while amylose is generally considered as an amorphous polymer with little or no impact on the overall crystalline organization.

11p system191 01-06-2013 45 4   Download

The case of homologous monomeric c-type and oligomeric b-type crystallins has been described and analyzed in evolutionary terms. Data and hypotheses from molecular genetics and structural investigations converge and suggest a novel three-phase model for the evolutionary history of crystallin-type proteins. In the divergent cascades of monomeric and oligomeric crystallins, a pivotal role was played by alterations in the gene segments encoding the C-terminal extensions and the intermotif or interdomain linker peptides.

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Oligomerization into multimeric complexes is a prerequisite for the chaperone function of almost all a-crystallin type heat shock proteins (a-Hsp), but the molecular details of complex assembly are poorly understood. The a-Hsp proteins from Bradyrhizobium japonicum are suitable bacterial models for structure-function studies of these ubiquitous stress proteins. They fall into two distinct classes, A and B, display chaperone activity in vitro and form oligomers of  24 subunits.

9p research12 01-06-2013 49 6   Download

Oviparously developing embryos of the brine shrimp, Artemia franciscana, synthesize abundant quantities of a small heat shock/a-crystallin protein, termed p26. Wild-type p26 functions as a molecular chaperone in vitro and is thought to help encysted Artemia embryos survive severe physiological stress encountered during diapause and anoxia. Full-length and truncated p26 cDNA derivatives were generated by PCR amplification of p26-3-6-3, then cloned in either pET21(+) or pRSETC and expressed in Escherichia coli BL21(DE3)....

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Mycobacterium tuberculosisheat shock protein 16.3 (MTB HSP 16.3) accumulates as the dominant protein in the latent stationary phase of tuberculosis infection. MTB HSP 16.3 displays several characteristics of small heat shock proteins (sHsps): its expression is increased in response to stress, it protects against protein aggregationin vitro, and it contains thecoreÔa-crystallinÕdomainfound inall sHsps.

8p research12 23-04-2013 35 2   Download

The interaction of bacterial endotoxins [lipopolysaccharide (LPS) and the
endotoxic principle lipid A], with high-den-sity lipoprotein (HDL) from serum was investigated with a variety of physical techniques and biological assays. HDL exhibited an increase in the gel to liquid crystalline phase transition temperature Tc and a rigidification of the acyl chains of the endotoxins as measured by Fourier-transform infrared spectroscopy and differential scanningcalorimetry.

10p tumor12 22-04-2013 38 3   Download

Duckd2-crystallin is a soluble tetrameric lens protein. In the presence of guanidinium hydrochloride (GdnHCl),it undergoes stepwise dissociation and unfolding. Gel-filtra-tion chromatography and sedimentation velocity analysis has demonstrated the dissociation of the tetramer protein to a monomeric intermediate with a dissociation constant of 0.34lM 3 . Dimers were also detected during the dissociation and refoldingprocesses.

8p tumor12 20-04-2013 34 1   Download

A cellulase (endo-b-1,4-glucanase, EC 3.2.1.4) was purified from the gut of larvae of the yellow-spotted longicorn beetle Psacothea hilarisby acetone precipitation and elution from gels after native PAGE and SDS/PAGE with activity staining. The purified protein formed a single band, and the molecular mass was estimated to be 47 kDa. The purified cellulasedegradedcarboxymethylcellulose (CMC), insoluble cello-oligosaccharide (average degree of polymerization 34) and soluble cello-oligosaccharides longer than cellotriose, but not crystalline cellulose or cellobiose. ...

6p tumor12 20-04-2013 40 5   Download

We report a comprehensive physicochemical characteriza-tion of a glycoglycerolipid from Mycoplasma fermentans, MfGl-II, in relation to its bioactivityand compared thiswith the respective behaviors of phosphatidylcholine (PC) and a bacterial glycolipid, lipopolysaccharide (LPS) from deep rough mutantSalmonella minnesotastrain R595. Theb«a gel-to-liquid crystalline phase transition behavior of the hydrocarbon chains withTc¼30Cfor MfGl-II as well as for LPS exhibits high similarity between the two glycolipids.

9p tumor12 20-04-2013 32 2   Download

Embryos of the brine shrimp,Artemia franciscana, exhibit remarkable resistance to physiological stress, which is tem-porally correlated with the presence of two proteins, one a small heat shock/a-crystallin protein termed p26 and the other called artemin, of unknown function.Artemin was sequenced previously by Edman degradation, and its rela-tionship to ferritin, an iron storage protein, established.The isolation from anArtemiaexpressed sequence tag library of artemin and ferritin cDNAs extends this work. ...

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Using synchrotron X-ray diffraction the thermal behaviour was studied of the cubic phases in the 1-monooleoyl-rac-glycerol (MO)/n-octyl-b-D-glucopyranoside (OG)/ 2 H2O system with 58 or 45 wt % MO concentration and varying OG/ 2 H2O contents. These MO contents correspond to a Pn3mcubic single-phase or aPn3mcubic phase in excess water on the binary MO/water axis of the ternary phase diagram. The cubic liquid crystalline phases are stable with small fractions of OG, while higher OG concentrations trigger a cubic-to-lamellar phase transition. ...

10p tumor12 20-04-2013 38 3   Download

a-Crystallin, a molecular chaperone and lens structural protein protects soluble enzymes against heat-induced aggregation and inactivation by a variety of molecules. In this study we investigated the chaperone function ofa-crys-tallininamorephysiological systeminwhicha-crystallinwas incorporated into red cell
ghosts. Its ability to protect the intrinsic membrane protein Na/K-ATPase from external stresses was studied. Red cell ghosts were created by lysing the red cells and removing cytoplasmic contents by size-exclusion chromatography. ...

7p fptmusic 16-04-2013 48 2   Download

Small heat shock proteins (sHSPs) function as molecular chaperones, pre-venting stress induced aggregation of partially denatured proteins and pro-moting their return to native conformations when favorable conditions pertain. Sequence similarity between sHSPs resides predominately in an internal stretch of residues termed the a-crystallin domain, a region usually flanked by two extensions.

15p awards 06-04-2013 37 3   Download

Thebandccrystallins are evolutionarily related families of proteins that make up a large part of the refractive structure of the vertebrate eye lens. Each family has a distinctive gene structure that reflects a history of succes-sive gene duplications. A survey ofc-crystallins expressed in mammal, rep-tile, bird and fish species (particularly in the zebrafish, Danio rerio) has led to the discovery of cN-crystallin, an evolutionary bridge between theband cfamilies.

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Geodin is a protein encoded by a sponge gene homologous to genes from the bc-crystallins superfamily. The interest for this crystallin-type protein stems from the phylogenesis of porifera, commonly called sponges, the earliest divergence event in the history of metazoans. Here we report the preparation of geodin as a recombinant protein fromEscherichia coli, its characterization through physico-chemical analyses, and a model of its 3D structure based on homology modelling.

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a-Crystallin is the principal lens protein which, in addition to its structural role, also acts as a molecular chaperone, to prevent aggregation and preci-pitation of other lens proteins. One of its two subunits,aB-crystallin, is also expressed in many nonlenticular tissues, and a natural missense muta-tion, R120G, has been associated with cataract and desmin-related myopa-

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The mammalian small heat shock proteinaB-crystallin can be phosphorylated at three different sites, Ser19, Ser45 and Ser59. We compared the intracellular distribution of wild-type, nonphosphorylatable and all possible pseudophos-phorylation mutants ofaB-crystallin by immunoblot and immunocytochemical analyses of stable and transiently transfected cells. We observed that pseudophosphorylation at two (especially S19D/S45D) or all three (S19D/S45D/ S59D) sites induced the partial translocationofaB-crystallin from the detergent-soluble to the detergent-insoluble frac-tion....

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A hallmark ofa-crystallin-type small heat shock proteins (sHsps) is their highly dynamic oligomeric structure which promotes intermolecular interactions involved in subunit exchange and substrate binding (chaperone-like activity). We studied the oligomeric features of two classes of bacterial sHsps by size exclusion chromatography and nanoelectro-spray mass spectrometry.Proteins of both classes formed large complexes that rapidly dissociated upon dilution and at physiologically relevant heat shock temperatures....

10p dell39 03-04-2013 45 3   Download