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1.
Inorg Chem ; 59(7): 4527-4535, 2020 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-32181663

RESUMO

The in-gel detection of proteins for various proteomic experiments is commonly done with the fluorescent RuII tris(bathophenanthroline disulfonate) complex (Ru(BPS)3), which is more cost-effective compared to commercial Ru-based formulations but requires tedious procedures for its preparation and strongly acidic staining conditions. Herein, we report the synthesis and characterization of heteroleptic RuII complexes Ru(BPS)2(BP) and Ru(BPS)(BP)2 containing bathophenanthroline (BP) and bathophenanthroline disulfonate disodium salt (BPS) in comparison with Ru(BPS)3. It was shown by fluorescent and UV-vis measurements that novel RuII complexes were excitable in both UV and visible light, close to emission bands of classical lasers, which is important for successful in-gel protein detection. Novel fluorescent dyes demonstrated improved protein detection in comparison with commercially available SYPRO Ruby staining solution. In addition, unlike commonly used staining protocols, staining with Ru(BPS)(BP)2 can be performed at nearly neutral pH, thereby reducing artificial post-translational modifications (PTMs).

2.
Dalton Trans ; 49(2): 274-278, 2020 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-31803888

RESUMO

The industrial fluorination of UO2 to UF4 is based on a complex process involving the manipulation of a large amount of HF, a very toxic and corrosive gas. We present here a safer way to accomplish this reaction utilizing ionic liquid [Bmim][PF6] as a unique reaction medium and fluoride source.

3.
Org Biomol Chem ; 17(15): 3805-3811, 2019 04 10.
Artigo em Inglês | MEDLINE | ID: mdl-30916709

RESUMO

Gold(i) catalysed regio- and stereoselective intermolecular hydroamination of internal alkynes was developed for the effective synthesis of a series of (Z)-functionalised vinylazoles under solvent free conditions. The catalytic hydrogenation of the resulting enamines leads to substituted saturated azoles in good yields.

4.
Angew Chem Int Ed Engl ; 58(36): 12585-12589, 2019 09 02.
Artigo em Inglês | MEDLINE | ID: mdl-30908800

RESUMO

Enantiopure poly(lactic acid) (PLA) can form stereocomplexes when enantiomeric PLA chains are mixed in equivalent amounts. Such materials provide interesting features that might be suitable for numerous applications. Despite several advantages, the main drawback of PLA is its narrow window of processing, thus limiting its use for industrial applications. Reported herein are achiral iron complexes, that are highly active, productive, and stereoselective under mild reaction conditions for the ring-opening polymerization of lactide. The corresponding catalytic systems enable the production of stereoblock polymers with high molecular weights, allowing the formation of thermally stable and industrially relevant stereocomplexes.

5.
Inorg Chem ; 58(2): 1091-1099, 2019 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-30592422

RESUMO

Association of uranyl nitrate with the macrocycle [P8W48O184]40- in formate buffered aqueous solution leads to the formation of a new compound (K11.3Li8.1Na22)[(UO2)7.2(HCOO)7.8(P8W48O184)Cl8]·89H2O (1). Its characterization by XRD reveals a high disorder of the uranyl cations and the formation of monodimensional chains of anionic [(UO2)7.2(HCOO)7.8(P8W48O184)Cl8]41.4- entities linked through formate ligands. The uranyl species are located either in the coordinating sites of the macrocycle [P8W48O184]40- or at its surface. Further studies of the molecule by SAXS and TEM show that the 1D chain collapses to give rise to the formation of polydisperse spherically aggregated species with an average radius of 129 Å.

6.
Langmuir ; 35(2): 446-452, 2019 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-30565468

RESUMO

In presence of calcium ions, ß-lactoglobulin (BLG) unfolds and subsequently aggregates after heating. This process has important pharmaceutical and agroalimentary applications. Nowadays, the molecular mechanism of unfolding and BLG aggregation, and the role of calcium in the mechanism, is poorly understood. Actually, in most studies, data have been acquired at room temperature, after heating and after aggregation, which makes it difficult to establish a clear causal-temporal relation between calcium binding, heat, and aggregation. Thus, the goal of the present study is to get accurate, nanoscale data about the molecular events leading to BLG unfolding and calcium-dependent aggregation. The molecular transformation of BLG during heating has been investigated, using the NMR pulse field gradient technique, operating in a high field (900 MHz). Thanks to this technique, the molecular conformation of newly formed unfolded BLG molecules can be distinguished in a large pool of native ones. The present work shows that BLG at neutral pH at 65 °C displays fast, cooperative-like unfolding, in which no long-lived intermediary state (as a molten globule one) is detected, before aggregation. These data also indicate that calcium ions bind unfolded BLG in specific sites which might be a necessary feature to form the aggregate. Finally, these data also provide an NMR-based methodology to monitor the rate of protein unfolding using NMR.


Assuntos
Lactoglobulinas/metabolismo , Agregados Proteicos , Animais , Cálcio/metabolismo , Bovinos , Calefação , Temperatura Alta , Lactoglobulinas/química , Ressonância Magnética Nuclear Biomolecular , Ligação Proteica , Conformação Proteica , Multimerização Proteica , Desdobramento de Proteína
7.
Chem Sci ; 9(22): 5021-5032, 2018 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-29938031

RESUMO

A new strategy for the synthesis of large poly-oxo clusters bearing 38 tetravalent uranium atoms {U38} has been developed by controlling the water release from the esterification reaction between a carboxylic acid and an alcohol. The molecular entity [U38O56Cl40(H2O)2(ipa)20]·(ipa) x (ipa = isopropanol) was crystallized from the solvothermal reaction of a mixture of UCl4 and benzoic acid in isopropanol at temperature ranging from 70 to 130 °C. Its crystal structure reveals the molecular assembly of the UO2 fluorite-like inner core {U14} with oxo groups bridging the uranium centers. The {U14} core is further surrounded by six tetrameric sub-units of {U4} to form the {U38} cluster. Its surface is decorated by either bridging- and terminal chloride anions or terminal isopropanol molecules. Another synthesis using the same reactant mixture at room temperature resulted in the crystallization of a discrete dinuclear complex [U2Cl4(bz)4(ipa)4]·(ipa)0.5 (bz = benzoate), in which each uranium center is coordinated by two chlorine atoms, four oxygen atoms from carboxylate groups and two additional oxygen atoms from isopropanol. The slow production of water released from the esterification of isopropanol allows the formation of the giant cluster with oxo bridges linking the uranium atoms at a temperature above 70 °C, whereas no such oxo groups are present in the dinuclear complex formed at room temperature. The kinetics of {U38} crystallization as well as the ester formation are analyzed and discussed. SAXS experiments indicate that the {U38} species are not dominant in the supernatant, but hexanuclear entities which are closely related to the [U6O8] type are formed.

8.
Chemistry ; 23(45): 10777-10788, 2017 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-28488394

RESUMO

In the present study, we report the first silver-dependent enantiodivergent gold-catalysed reaction. The asymmetric intramolecular hydroamination of alkenes catalysed by the combination of a single chiral binuclear gold(I) chloride complex and silver perchlorate can afford both enantiomers of the products by a simple solvent change from toluene to methanol. Such an enantiodivergent reaction is strictly independent of the reaction temperature or of the nature of the catalyst anion and displays the same first-order kinetic rate law with respect to substrate concentration in both solvents. Beyond a simple solvent effect the enantioinversion is controlled by gold-silver chloride adducts which occur only in methanol and allow a dual activation of the reagent. While one single gold atom activates the alkene moiety, the other gold atom forms an oxophilic gold-silver chloride adduct which is likely to interact with the carbamate function. By comparison with toluene, which affords (S)-enantiomer, this proximal and bimetallic activation would allow an opposite stereodifferentiation of the two diastereomeric intermediates during the final protodeauration step and lead therefore to the (R)-enantiomer.

9.
J Am Chem Soc ; 139(17): 6217-6225, 2017 05 03.
Artigo em Inglês | MEDLINE | ID: mdl-28398052

RESUMO

We report here a unique example of an in situ generated aluminum initiator stabilized by a C2-symmetric salen ligand which shows a hitherto unknown high activity for the ROP of rac-lactide at room temperature. Using a simple and robust catalyst system, which is prepared from a salen complex and an onium salt, this convenient route employs readily available reagents that afford polylactide in good yields with narrow polydispersity indices, without the need for time-consuming and expensive processes that are typically required for catalyst preparation and purification. In line with the experimental evidence, DFT studies reveal that initiation and propagation proceed via an external alkoxide attack on the coordinated monomer.

10.
J Mol Biol ; 428(22): 4544-4558, 2016 11 06.
Artigo em Inglês | MEDLINE | ID: mdl-27725184

RESUMO

AMSH [associated molecule with a Src homology 3 domain of signal transducing adaptor molecule (STAM)] is one of the deubiquitinating enzymes associated in the regulation of endocytic cargo trafficking. It shows an exquisite selectivity for Lys63-linked polyubiquitin chains that are the main chains involved in cargo sorting. The first step requires the ESCRT-0 complex that comprises the STAM and hepatocyte growth factor-regulated substrate (Hrs) proteins. Previous studies have shown that the presence of the STAM protein increases the efficiency of Lys63-linked polyubiquitin chain cleavage by AMSH, one of the deubiquitinating enzyme involved in lysosomal degradation. In the present study, we are seeking to understand if a particular structural organization among these three key players is responsible for the stimulation of the catalytic activity of AMSH. To address this question, we first monitored the interaction between the ubiquitin interacting motif (UIM)-SH3 construct of STAM2 and the Lys63-linked diubiquitin (Lys63-Ub2) chains by means of NMR. We show that Lys63-Ub2 is able to bind either the UIM or the SH3 domain without any selectivity. We further demonstrate that the SH3 binding motif (SBM) of AMSH (AMSH-SBM) outcompetes Lys63-Ub2 for binding SH3. Additionally, we show how different AMSH-SBM variants, modified by their sequence and length, exhibit similar equilibrium dissociation constants when binding SH3 but significantly differ in their dissociation rate constants. Finally, we report the solution NMR structure of the AMSH-SBM/SH3 complex and propose a structural organization where the AMSH-SBM interacts with the STAM2-SH3 domain and contributes to the correct positioning of AMSH prior to polyubiquitin chains' cleavage.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/química , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Complexos Endossomais de Distribuição Requeridos para Transporte/química , Complexos Endossomais de Distribuição Requeridos para Transporte/metabolismo , Espectroscopia de Ressonância Magnética , Ubiquitina Tiolesterase/química , Ubiquitina Tiolesterase/metabolismo , Ubiquitinas/química , Ubiquitinas/metabolismo , Humanos , Modelos Biológicos , Modelos Moleculares , Ligação Proteica
11.
Int J Syst Evol Microbiol ; 66(9): 3694-3702, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27375118

RESUMO

From our recent survey of non-pigmented rapidly growing mycobacteria in the Parisian water system, three groups of isolates (taxons 1-3) corresponding to possible novel species were selected for taxonomic study. The three taxa each formed creamy white, rough colonies, had an optimal growth temperature of 30 °C, hydrolyzed Tween 80, were catalase-positive at 22 °C and expressed arylsulfatase activity. All three were susceptible to amikacin, ciprofloxacin and tigecycline. The three taxa produced specific sets of mycolic acids, including one family that has never previously been described, as determined by thin layer chromatography and nuclear magnetic resonance. The partial rpoB sequences (723 bp) showed 4-6 % divergence from each other and more than 5 % differences from the most similar species. Partial 16S rRNA gene sequences showed 99 % identity within each species. The most similar sequences for 16S rRNA genes (98-99 % identity over 1444-1461 bp) were found in the Mycobacterium fortuitum group, Mycobacterium septicum and Mycobacterium farcinogenes. The three taxa formed a new clade (bootstrap value, 99 %) on trees reconstructed from concatenated partial 16S rRNA, hsp65 and rpoB sequences. The above results led us to propose three novel species for the three groups of isolates, namely Mycobacterium lutetiense sp. nov. [type strain 071T=ParisRGMnew_1T (CIP 110656T=DSM 46713T)], Mycobacterium montmartrense sp. nov. [type strain 196T=ParisRGMnew_2T (CIP 110655T=DSM 46714T)] and Mycobacteriu marcueilense sp. nov. [type strain of 269T=ParisRGMnew_3T (CIP 110654T=DSM 46715T)].


Assuntos
Mycobacterium/classificação , Filogenia , Microbiologia da Água , Abastecimento de Água , Técnicas de Tipagem Bacteriana , DNA Bacteriano/genética , Mycobacterium/genética , Mycobacterium/isolamento & purificação , Ácidos Micólicos/metabolismo , Paris , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
12.
ChemSusChem ; 9(12): 1413-23, 2016 06 22.
Artigo em Inglês | MEDLINE | ID: mdl-27115079

RESUMO

The catalytic conversion of alcohols into carboxylic acid salts in water was performed in the presence of ruthenium complexes supported by aliphatic PNP pincer ligands preformed or formed in situ. High activity toward a wide substrate scope was achieved with turnover number values of up to 4000. The air-stable catalytic system can be recycled by using toluene as a catalyst-immobilizing phase; the activity is maintained after five consecutive runs. Finally, mechanistic studies allowed some fundamental aspects related to water activation to be unveiled and to the mechanism postulated.


Assuntos
Álcoois/química , Ácidos Carboxílicos/química , Reciclagem , Sais/química , Água/química , Catálise , Hidrogenação , Rutênio/química
13.
J Biol Chem ; 291(18): 9666-77, 2016 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-26921321

RESUMO

The spores of the Bacillus cereus group (B. cereus, Bacillus anthracis, and Bacillus thuringiensis) are surrounded by a paracrystalline flexible yet resistant layer called exosporium that plays a major role in spore adhesion and virulence. The major constituent of its hairlike surface, the trimerized glycoprotein BclA, is attached to the basal layer through an N-terminal domain. It is then followed by a repetitive collagen-like neck bearing a globular head (C-terminal domain) that promotes glycoprotein trimerization. The collagen-like region of B. anthracis is known to be densely substituted by unusual O-glycans that may be used for developing species-specific diagnostics of B. anthracis spores and thus targeted therapeutic interventions. In the present study, we have explored the species and domain specificity of BclA glycosylation within the B. cereus group. First, we have established that the collagen-like regions of both B. anthracis and B. cereus are similarly substituted by short O-glycans that bear the species-specific deoxyhexose residues anthrose and the newly observed cereose, respectively. Second we have discovered that the C-terminal globular domains of BclA from both species are substituted by polysaccharide-like O-linked glycans whose structures are also species-specific. The presence of large carbohydrate polymers covering the surface of Bacillus spores may have a profound impact on the way that spores regulate their interactions with biotic and abiotic surfaces and represents potential new diagnostic targets.


Assuntos
Bacillus anthracis/fisiologia , Bacillus cereus/fisiologia , Glicoproteínas de Membrana/metabolismo , Polissacarídeos Bacterianos/metabolismo , Glicosilação , Glicoproteínas de Membrana/genética , Polissacarídeos Bacterianos/genética , Estrutura Terciária de Proteína , Especificidade da Espécie , Esporos Bacterianos
14.
Inorg Chem ; 54(17): 8271-80, 2015 Sep 08.
Artigo em Inglês | MEDLINE | ID: mdl-26301948

RESUMO

The reaction of Na10[α-SiW9O34] with tetravalent metallic cations such as 4f ((NH4)2Ce(NO3)6), 5d (HfCl4), or 5f (UCl4 and Th(NO3)4) in a pH 4.7 sodium acetate buffer solution leads to the formation of four sandwich-type polyoxometalates [Ce4(µ(3)-O)2(SiW9O34)2(CH3COO)2](10-) (1), [U4(µ(3)-O)2(SiW9O34)2(CH3COO)2](10-) (2), [Th3(µ(3)-O)(µ(2)-OH)3(SiW9O34)2](13-) (3), and [Hf3(µ(2)-OH)3(SiW9O34)2](11-) (4). All four compounds consist of a polynuclear cluster fragment stabilized by two [α-SiW9O34](10-) polyanions. Compounds 1 and 2 are isostructural with a tetranuclear core (Ce4, U4), while compound 3 presents a trinuclear Th3 core bearing a µ(3)-O-centered bridge. It is an unprecedented configuration in the case of the thorium(IV) cluster. Compound 4 also possesses a trinuclear Hf3 core but with the absence of the µ(3)-O bridge. The molecules have been characterized by single-crystal X-ray diffraction, (183)W and (29)Si nuclear magnetic resonance (NMR) spectroscopy, infrared (IR) spectroscopy, thermogravimetric analysis (TGA), and scanning electron microscopy/energy-dispersive X-ray (SEM/EDX) analysis.


Assuntos
Cério/química , Háfnio/química , Tório/química , Compostos de Tungstênio/química , Urânio/química , Oxigênio/química , Silício/química
15.
Inorg Chem ; 54(16): 7673-83, 2015 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-26208250

RESUMO

[Mo6X14](2-) octahedral molybdenum clusters are the main building blocks of a large range of materials. Although (95)Mo nuclear magnetic resonance was proposed to be a powerful tool to characterize their structural and dynamical properties in solution, these measurements have never been complemented by theoretical studies which can limit their interpretation for complex systems. In this Article, we use quantum chemical calculations to evaluate the (95)Mo chemical shift of three clusters: [Mo6Cl14](2-), [Mo6Br14](2-), and [Mo6I14](2-). In particular, we test various computational parameters influencing the quality of the results: size of the basis set, treatment of relativistic and solvent effects. Furthermore, to provide quantum chemical calculations that are directly comparable with experimental data, we evaluate for the first time the (95)Mo nuclear magnetic shielding of the experimental reference, namely, MoO4(2-) in aqueous solution. This is achieved by combining ab initio molecular dynamics simulations with a periodic approach to evaluate the (95)Mo nuclear shieldings. The results demonstrate that, despite the difficulty to obtain accurate (95)Mo chemical shifts, relative values for a cluster series can be fairly well-reproduced by DFT calculations. We also show that performing an explicit solvent treatment for the reference compound improves by ∼50 ppm the agreement between theory and experiment. Finally, the standard deviation of ∼70 ppm that we calculate for the (95)Mo nuclear shielding of the reference provides an estimation of the accuracy we can achieve for the calculation of the (95)Mo chemical shifts using a static approach. These results demonstrate the growing ability of quantum chemical calculations to complement and interpret complex experimental measurements.


Assuntos
Molibdênio/química , Teoria Quântica , Isótopos , Espectroscopia de Ressonância Magnética , Conformação Molecular , Simulação de Dinâmica Molecular , Solventes/química
16.
Inorg Chem ; 54(12): 6043-54, 2015 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-26024151

RESUMO

For the first time, hexanuclear complexes with general chemical formula [Ln6O(OH)8(NO3)6(H2O)n](2+) with n = 12 for Ln = Sm-Lu and Y and n = 14 for Ln = Pr and Nd were stabilized as nanoaggregates in ethylene glycol (EG). These unprecedented nanoaggregates were structurally characterized by (89)Y and (1)H NMR spectroscopy, UV-vis absorption and luminescence spectroscopies, electrospray ionization mass spectrometry, diffusion ordered spectroscopy, transmission electron microscopy, and dynamic light scattering. These nanoaggregates present a 200 nm mean solvodynamic diameter. In these nanoaggregates, hexanuclear complexes are isolated and solvated by EG molecules. The replacement of ethylene glycol by 2-hydroxybenzyl alcohol provides new nanoaggregates that present an antenna effect toward lanthanide ions. This results in a significant enhancement of the luminescence properties of the aggregates and demonstrates the suitability of the strategy for obtaining highly tunable luminescent solutions.

17.
PLoS Pathog ; 10(5): e1004115, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24809459

RESUMO

Mycobacterium tuberculosis bacilli display two signature features: acid-fast staining and the capacity to induce long-term latent infections in humans. However, the mechanisms governing these two important processes remain largely unknown. Ser/Thr phosphorylation has recently emerged as an important regulatory mechanism allowing mycobacteria to adapt their cell wall structure/composition in response to their environment. Herein, we evaluated whether phosphorylation of KasB, a crucial mycolic acid biosynthetic enzyme, could modulate acid-fast staining and virulence. Tandem mass spectrometry and site-directed mutagenesis revealed that phosphorylation of KasB occurred at Thr334 and Thr336 both in vitro and in mycobacteria. Isogenic strains of M. tuberculosis with either a deletion of the kasB gene or a kasB_T334D/T336D allele, mimicking constitutive phosphorylation of KasB, were constructed by specialized linkage transduction. Biochemical and structural analyses comparing these mutants to the parental strain revealed that both mutant strains had mycolic acids that were shortened by 4-6 carbon atoms and lacked trans-cyclopropanation. Together, these results suggested that in M. tuberculosis, phosphorylation profoundly decreases the condensing activity of KasB. Structural/modeling analyses reveal that Thr334 and Thr336 are located in the vicinity of the catalytic triad, which indicates that phosphorylation of these amino acids would result in loss of enzyme activity. Importantly, the kasB_T334D/T336D phosphomimetic and deletion alleles, in contrast to the kasB_T334A/T336A phosphoablative allele, completely lost acid-fast staining. Moreover, assessing the virulence of these strains indicated that the KasB phosphomimetic mutant was attenuated in both immunodeficient and immunocompetent mice following aerosol infection. This attenuation was characterized by the absence of lung pathology. Overall, these results highlight for the first time the role of Ser/Thr kinase-dependent KasB phosphorylation in regulating the later stages of mycolic acid elongation, with important consequences in terms of acid-fast staining and pathogenicity.


Assuntos
3-Oxoacil-(Proteína de Transporte de Acila) Sintase/metabolismo , Proteínas de Bactérias/metabolismo , Mycobacterium tuberculosis/metabolismo , Mycobacterium tuberculosis/patogenicidade , Ácidos Micólicos/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , 3-Oxoacil-(Proteína de Transporte de Acila) Sintase/genética , Animais , Proteínas de Bactérias/genética , Domínio Catalítico/genética , Parede Celular/metabolismo , Metabolismo dos Lipídeos/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos SCID , Técnicas Microbiológicas/métodos , Modelos Moleculares , Mycobacterium tuberculosis/genética , Ácidos Micólicos/química , Fosforilação , Coloração e Rotulagem/métodos , Tuberculose/diagnóstico , Tuberculose/metabolismo , Tuberculose/microbiologia , Virulência
18.
J Biol Chem ; 287(25): 21372-83, 2012 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-22514274

RESUMO

Carbon assimilation in plants is regulated by the reduction of specific protein disulfides by light and their re-oxidation in the dark. The redox switch CP12 is an intrinsically disordered protein that can form two disulfide bridges. In the dark oxidized CP12 forms an inactive supramolecular complex with glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and phosphoribulokinase, two enzymes of the carbon assimilation cycle. Here we show that binding of CP12 to GAPDH, the first step of ternary complex formation, follows an integrated mechanism that combines conformational selection with induced folding steps. Initially, a CP12 conformation characterized by a circular structural motif including the C-terminal disulfide is selected by GAPDH. Subsequently, the induced folding of the flexible C-terminal tail of CP12 in the active site of GAPDH stabilizes the binary complex. Formation of several hydrogen bonds compensates the entropic cost of CP12 fixation and terminates the interaction mechanism that contributes to carbon assimilation control.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Proteínas de Transporte/metabolismo , Fotossíntese/fisiologia , Dobramento de Proteína , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Transporte/genética , Dissulfetos/metabolismo , Estabilidade Enzimática/fisiologia , Gliceraldeído-3-Fosfato Desidrogenase (NADP+)(Fosforiladora)/genética , Gliceraldeído-3-Fosfato Desidrogenase (NADP+)(Fosforiladora)/metabolismo , Complexos Multienzimáticos/genética , Complexos Multienzimáticos/metabolismo , Fosfotransferases (Aceptor do Grupo Álcool)/genética , Fosfotransferases (Aceptor do Grupo Álcool)/metabolismo
19.
Phys Chem Chem Phys ; 13(33): 15103-21, 2011 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-21792425

RESUMO

Molecular dynamics simulations describing the solvation process of native and modified cyclodextrins (per-substituted α-, ß-, and γ-cyclodextrins, as well as an amino-acid derived ß-cyclodextrin) have been performed. A homogeneous force field, namely "q4md-CD", has been built from the development of a new force field topology database and from a combination of the GLYCAM04 and Amber99SB force fields to correctly describe the geometrical, structural, dynamical and hydrogen bonding aspects of heterogeneous cyclodextrin based systems. These include native, organo- and peptidic-linked cyclodextrins. q4md-CD features: (i) geometrical parameters from Amber99SB to describe the protein parts, (ii) geometrical parameters from GLYCAM04 for the carbohydrate and organic parts when available or those of Amber99SB otherwise, (iii) partial atomic charges, embedded in force field libraries for the carbohydrate and organic fragments, were derived using the R.E.D. tools according to the "Amber" strategy and (iv) scaling factors of 1.2 and 2.0 were imposed for the 1-4 electrostatic and 1-4 van der Waals interactions, respectively. Results given by q4md-CD on native cyclodextrins have been compared to those obtained with reference to force fields like GLYCAM04, GLYCAM06 and Amber99SB as well as with experimental data. This work not only gives a global view of the performances of the aforementioned force fields towards a correct description of solvated cyclodextrins, but also extends the capabilities of current force fields by addressing some issues concerning hydrogen bonding and opens new possibilities towards studies of glycoconjugates by molecular dynamics.


Assuntos
Ciclodextrinas/química , Simulação de Dinâmica Molecular , Ligação de Hidrogênio , Estrutura Molecular , Estereoisomerismo
20.
Biofouling ; 27(7): 751-61, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21777114

RESUMO

The role of the BclA domains of B. cereus ATCC 14579 was investigated in order to understand the phenomena involved in the interfacial processes occurring between spores and inert surfaces. This was done by (i) creating deletions in the collagen-like region (CLR) and the C-terminal domain (CTD) of BclA, (ii) building BclA proteins with various lengths in the CLR and (iii) modifying the hydrophobic upper surface in the CTD. First, it was demonstrated that the CLR was substituted by three residues already reported in the CLR of B. anthracis, viz. rhamnose, 3-O-methyl-rhamnose, and GalNH(2) residues, while the CTD was also substituted by two additional glycosyl residues, viz. 2-O-methyl-rhamnose and 2,4-O-methyl-rhamnose. Regarding the properties of the spores, both CLR and CTD contributed to the adhesion of the spores, which was estimated by measuring the resistance to detachment of spores adhered to stainless steel plates). CLR and CTD also impacted the hydrophobic character and isoelectric point of the spores. It was then shown that the resistance to detachment of the spores was not affected by the physicochemical properties, but by the CLR length and the presence of hydrophobic amino acids on the CTD.


Assuntos
Bacillus cereus/fisiologia , Colágeno , Glicoproteínas de Membrana/química , Glicoproteínas de Membrana/metabolismo , Estrutura Terciária de Proteína , Esporos Bacterianos/fisiologia , Bacillus cereus/química , Bacillus cereus/genética , Aderência Bacteriana , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Colágeno/química , Colágeno/genética , Colágeno/metabolismo , Glicosilação , Glicoproteínas de Membrana/genética , Mutação , Oligossacarídeos/análise , Estrutura Terciária de Proteína/genética , Estrutura Terciária de Proteína/fisiologia , Ramnose/análise , Esporos Bacterianos/química , Aço Inoxidável , Propriedades de Superfície
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