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81.
82.
Dr. Bettina Sommer Dr. Holger von Moeller Martina Haack Dr. Farah Qoura Clemens Langner Dr. Gleb Bourenkov Dr. Daniel Garbe Dr. Bernhard Loll Prof. Dr. Thomas Brück 《Chembiochem : a European journal of chemical biology》2015,16(1):110-118
Isobutanol is deemed to be a next‐generation biofuel and a renewable platform chemical. 1 Non‐natural biosynthetic pathways for isobutanol production have been implemented in cell‐based and in vitro systems with Bacillus subtilis acetolactate synthase (AlsS) as key biocatalyst. 2 – 6 AlsS catalyzes the condensation of two pyruvate molecules to acetolactate with thiamine diphosphate and Mg2+ as cofactors. AlsS also catalyzes the conversion of 2‐ketoisovalerate into isobutyraldehyde, the immediate precursor of isobutanol. Our phylogenetic analysis suggests that the ALS enzyme family forms a distinct subgroup of ThDP‐dependent enzymes. To unravel catalytically relevant structure‐function relationships, we solved the AlsS crystal structure at 2.3 Å in the presence of ThDP, Mg2+ and in a transition state with a 2‐lactyl moiety bound to ThDP. We supplemented our structural data by point mutations in the active site to identify catalytically important residues. 相似文献
83.
Díaz MD Palomino-Schätzlein M Corzana F Andreu C Carbajo RJ del Olmo M Canales-Mayordomo A Pineda-Lucena A Asensio G Jiménez-Barbero J 《Chembiochem : a European journal of chemical biology》2010,11(17):2424-2432
The conformations of two synthetic pentapeptides with antimicrobial activity and their 4-fluorophenylalanine (Pff)-containing analogues (ArXArXAr-NH(2); Ar=Phe, Pff; X=Lys, Arg) have been studied. NMR experiments carried out both in aqueous fluoroalcohol solutions and SDS micelles permitted their interactions with membrane-like environments to be explored. WaterLOGSY experiments and Mn(2+)-based paramagnetic probes were also applied to assess their orientations with respect to the SDS micelles. In addition, pulse-field gradient (PFG) diffusion NMR spectroscopy studies were conducted, under different experimental conditions (i.e., concentration, temperature) to characterize the possible changes in the peptides' aggregation states as a putative critical factor for their antimicrobial activity. Finally, molecular dynamics simulations on a variety of conformations showed the intrinsic flexibility of these peptides in both aqueous solutions and membrane-mimetic systems. 相似文献
84.
Martina Baeumler Frank Gütle Vladimir Polyakov Markus Cäsar Michael Dammann Helmer Konstanzer Wilfried Pletschen Wolfgang Bronner Rüdiger Quay Patrick Waltereit Michael Mikulla Oliver Ambacher Franck Bourgeois Reza Behtash Klaus J. Riepe Paul J. van der Wel Jos Klappe Thomas Rödle 《Journal of Electronic Materials》2010,39(6):756-760
85.
Martina Gensini Dr. Maria Altamura Dr. Tula Dimoulas Dr. Valentina Fedi Dr. Danilo Giannotti Dr. Sandro Giuliani Dr. Antonio Guidi Dr. Nicholas J. S. Harmat Dr. Stefania Meini Dr. Rossano Nannicini Franco Pasqui Manuela Tramontana Dr. Antonio Triolo Dr. Carlo Alberto Maggi Dr. 《ChemMedChem》2010,5(1):65-78
Herein we describe the synthesis of a series of new potent tachykinin NK2 receptor antagonists by the modulation of the C‐ and N‐terminal moieties of ibodutant (MEN 15596, 1 ). The N‐terminal benzo[b]thiophene ring was replaced by different substituted naphthalenes and benzofurans, while further modifications were evaluated at the C‐terminal tetrahydropyran moiety. Most compounds demonstrated a high affinity for the human NK2 receptor and high in vitro antagonist potency, indicating that a wide range of substituents at both termini can be incorporated in the molecule without detrimental effects on the interactions with the NK2 receptor. Selected compounds were tested in vivo confirming their activity as NK2 antagonists. In particular, after both iv and id administration to guinea pig, compound 61 b was able to antagonize NK2‐induced colonic contractions with a potency and duration‐of‐action fully comparable to the reference compound 1 (MEN 15596, ibodutant). 相似文献
86.
Martina Rejtharová Libor Rejthar Katarína Čačková 《Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment》2018,35(2):233-240
A sensitive and robust confirmatory method for determination of steroid esters in blood serum is essential for reliable monitoring of possible illegal use of steroid hormones as growth promoters in meat production. A previously used sample preparation methodology was improved. The procedure consists of protein precipitation and removal of phospholipids by dispersive SPE Supel? QuE Z-Sep (Sigma-Aldrich) followed by clean-up on alumina column and LC-MS/MS measurement. The modified method has been validated according to Commission Decision 2002/657/EC. Validation parameters for determination of six testosterone esters and five nortestosterone esters in bovine and porcine blood serum are presented in this article. Decision limits for all analytes were observed in the range 10–20 pg mL?1. The method described is considerably robust for bovine and porcine serum analyses and can be applied both for screening and confirmatory determination in routine residue monitoring. 相似文献
87.
Determination of Lutein from Fruit and Vegetables Through an Alkaline Hydrolysis Extraction Method and HPLC Analysis 下载免费PDF全文
Alessandra Fratianni Rossella Mignogna Serena Niro Gianfranco Panfili 《Journal of food science》2015,80(12):C2686-C2691
A simple and rapid analytical method for the determination of lutein content, successfully used for cereal matrices, was evaluated in fruit and vegetables. The method involved the determination of lutein after an alkaline hydrolysis of the sample matrix, followed by extraction with solvents and analysis by normal phase HPLC. The optimized method was simple, precise, and accurate and it was characterized by few steps that could prevent loss of lutein and its degradation. The optimized method was used to evaluate the lutein amounts in several fruit and vegetables. Rich sources of lutein were confirmed to be green vegetables such as parsley, spinach, chicory, chard, broccoli, courgette, and peas, even if in a range of variability. Taking into account the suggested reference values these vegetables can be stated as good sources of lutein. 相似文献
88.
A strategic analysis of the electricity market in Western Australia yields a market potential for renewable energy in Western Australia. However, from a purely financial viewpoint the installation of grid-connected pv-systems still is not economically viable. In this paper a balanced scorecard (BSC) is developed to capture and visualize other than financial benefits. Therefore, the BSC can be used as a marketing tool to communicate the benefits of a privately owned GCPV system to potential customers. 相似文献
89.
90.
Atomic force microscopy (AFM) can image materials at the nanometer scale and obtain quantitative information
on their surface energy, roughness and hardness (Morris et al. 1999). AFM has also been used to quantify
changes in the surface properties of polymer films and coatings exposed to UV radiation or natural weathering,
but it has not been used to assess the photodegradation of wood (Biggs et al. 2001). The advantage of
using AFM to assess the photodegradation of polymers lies in its ability to reveal early changes in the
material on a nanometer scale and elucidate mechanisms responsible for such degradation. This study examined
if AFM could provide similar information and insights for wood exposed to solar radiation. 相似文献