Self-assembly Dotaz Zobrazit nápovědu
Ameloblastin (AMBN), an important component of the self-assembled enamel extra cellular matrix, contains several in silico predicted phosphorylation sites. However, to what extent these sites actually are phosphorylated and the possible effects of such post-translational modifications are still largely unknown. Here we report on in vitro experiments aimed at investigating what sites in AMBN are phosphorylated by casein kinase 2 (CK2) and protein kinase A (PKA) and the impact such phosphorylation has on self-assembly and calcium binding. All predicted sites in AMBN can be phosphorylated by CK2 and/or PKA. The experiments show that phosphorylation, especially in the exon 5 derived part of the molecule, is inversely correlated with AMBN self-assembly. These results support earlier findings suggesting that AMBN self-assembly is mostly dependent on the exon 5 encoded region of the AMBN gene. Phosphorylation was significantly more efficient when the AMBN molecules were in solution and not present as supramolecular assemblies, suggesting that post-translational modification of AMBN must take place before the enamel matrix molecules self-assemble inside the ameloblast cell. Moreover, phosphorylation of exon 5, and the consequent reduction in self-assembly, seem to reduce the calcium binding capacity of AMBN suggesting that post-translational modification of AMBN also can be involved in control of free Ca(2+) during enamel extra cellular matrix biomineralization. Finally, it is speculated that phosphorylation can provide a functional crossroad for AMBN either to be phosphorylated and act as monomeric signal molecule during early odontogenesis and bone formation, or escape phosphorylation to be subsequently secreted as supramolecular assemblies that partake in enamel matrix structure and mineralization.
- Publikační typ
- časopisecké články MeSH
The conditions determining network-forming and aggregation properties of hyaluronan on the mica surface were studied. The hyaluronan was deposited on the surface from aqueous and saline solutions and attached by a bivalent cation. The morphology of the immobilized assemblies was characterized by atomic force microscopy. The experimental results show that the morphology and size of the aggregates as well as the density of the interconnecting fibrillar network, both made of hyaluronan, at the liquid-solid phase interface are determined not only by its molecular weight or concentration in solution, but also by the dissolution conditions and storage time. These findings extend the current state of knowledge about the conformational variability of this biologically important polymer. Understanding the conformational variability is of great importance, as it governs the physiological functions of hyaluronan, as well as its processability and formulations. That in turn determines its usability in different pharmacological and biomaterial applications.
- MeSH
- hydrofobní a hydrofilní interakce MeSH
- hypertonický solný roztok chemie MeSH
- kyselina hyaluronová chemie MeSH
- mikroskopie atomárních sil metody MeSH
- molekulární struktura MeSH
- molekulová hmotnost MeSH
- polymery chemie MeSH
- povrchové vlastnosti MeSH
- rozpustnost MeSH
- silikáty hliníku chemie MeSH
- skladování léků MeSH
- voda chemie MeSH
- vodíková vazba MeSH
- Publikační typ
- časopisecké články MeSH
Cobalt bis(dicarbollide) derivatives are promising therapeutic agents however their utilization is complicated due to their low solubility and self-assembling in water. Earlier we have shown that their solubility can be increased by using of suitable biocompatible excipients--carriers of pharmaceutically active compounds. Expected mechanism of solubilization was disassembling of self-assemblies and complexation of unimers. Newly our results of time-dependent light scattering study correct this presumption. Poor solubility of all derivatives can be easily improved by using various excipients, however only heptakis(2,6-di-O-methyl)-β-cyclodextrin displays ability to disassemble self-assemblies of all derivatives and suppress their self-assembling. Surprisingly, the other excipients participate on formation of mixed assemblies of derivative/excipient complex or cover assemblies to make them more soluble without decreasing their size.
- MeSH
- biologická dostupnost MeSH
- hydrodynamika MeSH
- kobalt chemie MeSH
- molekulární konformace MeSH
- molekulární modely MeSH
- organokovové sloučeniny chemie farmakokinetika MeSH
- radiační rozptyl MeSH
- rozpustnost MeSH
- světlo MeSH
- voda chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The formation of mineralized tissues is governed by extracellular matrix proteins that assemble into a 3D organic matrix directing the deposition of hydroxyapatite. Although the formation of bones and dentin depends on the self-assembly of type I collagen via the Gly-X-Y motif, the molecular mechanism by which enamel matrix proteins (EMPs) assemble into the organic matrix remains poorly understood. Here we identified a Y/F-x-x-Y/L/F-x-Y/F motif, evolutionarily conserved from the first tetrapods to man, that is crucial for higher order structure self-assembly of the key intrinsically disordered EMPs, ameloblastin and amelogenin. Using targeted mutations in mice and high-resolution imaging, we show that impairment of ameloblastin self-assembly causes disorganization of the enamel organic matrix and yields enamel with disordered hydroxyapatite crystallites. These findings define a paradigm for the molecular mechanism by which the EMPs self-assemble into supramolecular structures and demonstrate that this process is crucial for organization of the organic matrix and formation of properly structured enamel.
- MeSH
- amelogenin metabolismus MeSH
- aminokyselinové motivy fyziologie MeSH
- biologická evoluce MeSH
- extracelulární matrix - proteiny metabolismus MeSH
- hydroxyapatit metabolismus MeSH
- myši MeSH
- proteiny zubní skloviny metabolismus MeSH
- sekvence aminokyselin MeSH
- vazba proteinů fyziologie MeSH
- vnitřně neuspořádané proteiny metabolismus MeSH
- zubní sklovina metabolismus MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, N.I.H., Extramural MeSH
The preservation of enzymatic activity is a fundamental requirement for exploiting hybrid nano-bio-conjugates, and the control over protein-nanoparticle interactions, leading to stable and catalytically active hybrids, represents the key for designing new biosensing platforms. In this scenario, surface active maghemite nanoparticles (SAMNs) represent a new class of naked magnetic nanoparticles, displaying peculiar electrocatalytic features and the ability to selectively bind proteins. Recombinant aminoaldehyde dehydrogenase from tomato (SlAMADH1) was used as a model protein, and successfully immobilized by self-assembly on the surface of naked SAMNs, where its enzymatic activity resulted preserved for more than 6 months. The hybrid nanomaterial (SAMN@SlAMADH1) was characterized by UV-Vis spectroscopy, mass spectrometry, and TEM microscopy, and applied for the development of a biosensor for the determination of aminoaldehydes in alcoholic beverages. Measurements were carried out in a low volume electrochemical flow cell comprising a SAMN modified carbon paste electrode for the coulometric determination of the NADH produced during the enzymatic catalysis. The present findings, besides representing the first example of an electrochemical biosensor for aminoaldehydes in an alcoholic matrix, open the door to the use of immobilized enzymes on naked metal oxides nanomaterials for biosensing.
- MeSH
- aldehyddehydrogenasa metabolismus MeSH
- aldehydy analýza MeSH
- biosenzitivní techniky * MeSH
- elektrochemické techniky MeSH
- enzymy imobilizované metabolismus MeSH
- kovové nanočástice chemie MeSH
- propylaminy analýza MeSH
- Solanum lycopersicum enzymologie MeSH
- železité sloučeniny chemie MeSH
- Publikační typ
- časopisecké články MeSH
Supramolecular characteristics of two spermine amides of betulinic acid (1 and 2) were studied by measuring and evaluating their UV-VIS-NIR spectra in aqueous acetonitrile and DOSY-NMR spectra in tetradeuteromethanol, accompanied by atomic force microscopy (AFM) images, scanning electron microscopy (SEM) micrographs, and transmission electron microscopy (TEM) micrographs. Fibrous supramolecular self-assembly of 1 and 2 was observed by AFM images, as well as by the SEM and TEM micrographs. Bathochromic shifts of the absorbance maximum at 870nm to 1015-970nm in the UV-VIS-NIR spectra were observed with increasing water content in the acetonitrile/water systems, indicating formation of fibrous J-type aggregates. Variable temperature DOSY-NMR spectral measurement showed non-linear dependence that also suggests self-assembly behavior of the studied systems. Chiral supramolecular structures were formed by self-assembling due to the chirality of the monomeric molecules. Application of aqueous media during self-assembly procedures is an important factor in the development of targeted drug delivery systems.
In the Avocado Sunblotch Viroid (ASBVd: 249-nt) from the Avsunviroidae family, a symmetric rolling-circle replication operates through an autocatalytic mechanism mediated by hammerhead ribozymes (HHR) embedded in both polarity strands. The concatenated multimeric ASBVd (+) and ASBVd (-) RNAs thus generated are processed by cleavage to unit-length where ASBVd (-) self-cleaves with more efficiency. Absolute scale small angle neutron scattering (SANS) revealed a temperature-dependent dimer association in both ASBVd (-) and its derived 79-nt HHR (-). A joint thermodynamic analysis of SANS and catalytic data indicates the rate-determining step corresponds to the dimer/monomer transition. 2D and 3D models of monomeric and dimeric HHR (-) suggest that the inter-molecular contacts stabilizing the dimer (between HI and HII domains) compete with the intra-molecular ones stabilizing the active conformation of the full-length HHR required for an efficient self-cleavage. Similar competing intra- and inter-molecular contacts are proposed in ASBVd (-) though with a remoter region from an extension of the HI domain.
Chlorosomes, the light-harvesting antennae of green photosynthetic bacteria, are based on large aggregates of bacteriochlorophyll molecules. Aggregates with similar properties to those in chlorosomes can also be prepared in vitro. Several agents were shown to induce aggregation of bacteriochlorophyll c in aqueous environments, including certain lipids, carotenes, and quinones. A key distinguishing feature of bacteriochlorophyll c aggregates, both in vitro and in chlorosomes, is a large (>60 nm) red shift of their Q(y) absorption band compared with that of the monomers. In this study, we investigate the self-assembly of bacteriochlorophyll c with the xanthophyll astaxanthin, which leads to the formation of a new type of complexes. Our results indicate that, due to its specific structure, astaxanthin molecules competes with bacteriochlorophylls for the bonds involved in the aggregation, thus preventing the formation of any significant red shift compared with pure bacteriochlorophyll c in aqueous buffer. A strong interaction between both the types of pigments in the developed assemblies, is manifested by a rather efficient (~40%) excitation energy transfer from astaxanthin to bacteriochlorophyll c, as revealed by fluorescence excitation spectroscopy. Results of transient absorption spectroscopy show that the energy transfer is very fast (<500 fs) and proceeds through the S(2) state of astaxanthin.
- MeSH
- bakteriální proteiny chemie izolace a purifikace metabolismus MeSH
- bakteriochlorofyly chemie izolace a purifikace metabolismus MeSH
- Chlorobium chemie MeSH
- fotosyntéza MeSH
- přenos energie * MeSH
- spektrální analýza MeSH
- světlo MeSH
- světlosběrné proteinové komplexy chemie metabolismus MeSH
- xanthofyly chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Stereospecific nucleation of mesoporous hybrid microspheres composed of CaCO3 and carrageenan was appended to one side of bacterial cellulose membrane synthesized in static cultures of Gluconacetobacter hansenii to develop an implantable drug delivery device. The synthesis of the hybrid microparticles proceeds by self-assembly mechanism in the presence of calcium and contains tailorable amounts of doxorubicin. However, in the absence of the particles, doxorubicin was distributed along the BC film, but without control release of drug. Infrared spectroscopy, confocal and scanning electron microscopies analyses demonstrate that the doxorubicin is entrapped inside the hybrid particles with approximately 80% drug loading compared to the 11% obtained for native bacterial cellulose. Doxorubicin content in the hybrid particles can be increased by a factor of 10 (from 258.6 to 2586.3 nmol ml−1), and also by the quantities of particles regulated by the CaCO3–carrageenan content and the physicochemical microenvironment. The hybrid BC system can be considered as smart device since the kinetic release of doxorubicin from the hybrid cellulose system rise from 1.50 to 2.75 μg/membrane/day when the pH decreases from 7.4 to 5.8 at 37 °C, a pathologic simulated environment. The hybrid microparticle system can be potentially used as an implantable drug delivery system for personalized oncological therapies.
- MeSH
- antitumorózní látky aplikace a dávkování terapeutické užití toxicita MeSH
- bakteriální polysacharidy biosyntéza farmakologie metabolismus MeSH
- biomedicínský výzkum metody trendy MeSH
- celulosa * biosyntéza farmakologie MeSH
- doxorubicin aplikace a dávkování farmakologie MeSH
- elektronová mikroskopie metody využití MeSH
- Gluconacetobacter růst a vývoj účinky léků MeSH
- individualizovaná medicína metody trendy využití MeSH
- karagenan * biosyntéza metabolismus MeSH
- konfokální mikroskopie metody využití MeSH
- lidé MeSH
- nanokompozity chemie mikrobiologie využití MeSH
- spektrofotometrie infračervená metody využití MeSH
- statistika jako téma metody MeSH
- systémy cílené aplikace léků metody využití MeSH
- techniky in vitro MeSH
- uhličitan vápenatý * chemická syntéza metabolismus MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- práce podpořená grantem MeSH
