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901.
Paolo Ganis Donatella Furlani Daniele Marton Giuseppe Tagliavini Giovanni Valle 《Journal of organometallic chemistry》1985,293(2):207-212
The crystal structure of (C6H5)3SnCH2CHCH2 has been determined. The asymmetric unit consists of two molecules of triphenylallyltin having virtually the same conformation. Their geometrical parameters exclude pπ-dπ bonding between the metal and the allyl double bond, and seem to be in a better agreement with a σ-π conjugation effect. 相似文献
902.
De Gregorio A Battistutta R Arena N Panzalorto M Francescato P Valentini G Bruno G Zanotti G 《Organic & biomolecular chemistry》2003,1(18):3178-3185
Ornithine transcarbamoylase from ovine liver has been purified to homogeneity. Like all anabolic OTCs, the ovine enzyme is a trimer, constituted by identical subunits of 34 kDa. Sequence analysis of the 54 N-terminal residues of ovine OTC shows a high degree of homology with the human enzyme. The optimum pH and the Michaelis constants for the catalytic reaction were determined. The ovine enzyme is the most thermostable one among mammals OTCs, its critical temperature being 6 degrees C higher than those measured for the other enzymes. The enzyme has been crystallised and the structure determined at 3.5 A resolution. Crystals belong to the cubic P4(3)32 space group, with a = b = c = 184.7 A and a solvent content of about 80%. There is no evidence of any ligand in the active site cavity, indicating that the crystals contain an unliganded or T state of the enzyme. The unliganded OTCase enzyme adopts a trimeric structure which, in the crystal, presents a three-fold axis coincident with the crystallographic one. The conformation of each monomer in the trimer is quite similar to that of the liganded human protein, with the exception of a few loops, directly interacting with the substrate(s), which are able to induce a rearrangement of the quaternary organisation of the trimer, that accounts for the cooperative behaviour of the enzyme following the binding of the substrates. 相似文献
903.
A proteomic approach to study protein variation in GM durum wheat in relation to technological properties of semolina 总被引:1,自引:0,他引:1
Di Luccia A Lamacchia C Fares C Padalino L Mamone G La Gatta B Gambacorta G Faccia M Di Fonzo N La Notte E 《Annali di chimica》2005,95(6):405-414
Genetic manipulation of durum wheats by tobacco rab-1 genes influence the trafficking of gluten proteins through the secretory system by up- or down-regulating the transport step from the ER to the Golgi apparatus which may in turn modify functional performance of the grain. Gluten proteins were extracted from two genetically manipulated lines - Svevo B730 1-1 and Ofanto B688 1-2 - and their control lines and were analyzed by two dimensional gel electrophoresis. When the two-dimensional maps were compared by image analysis no significant differences between the GM line with an up-regulated trafficking containing the wild type tobacco rab1 (Svevo B730 1-1) and its control (Svevo control). By contrast, significant differences were found between the GM line with a down-regulated trafficking due to the tobacco rab1 mutant form (Ofanto B688 1-2) and its control (Ofanto control). Of the new protein spots detected in the down-regulated Ofanto B688 1-2 map, only a beta-amylase was identified. The remaining spots were susceptible to chymotripsin action but not to trypsin one, as in the case of the gluten protein. Rheological measurements showed that gluten quality was enhanced in the down-regulated Ofanto B688 1-2 without an increase in the amount of gluten. Proteomics is a useful and powerful tool for investigating protein changes in GMOs and in understanding events in food science and technology. 相似文献
904.
Antonio Costantino Fabretti Marco Ferrari Gian Carlo Franchini Carlo Preti Lorenzo Tassi Giuseppe Tosi 《Transition Metal Chemistry》1982,7(5):279-281
Summary The reaction of copper(II) chloride with 1,3-thiazolidine-2-thione in absolute ethanol yields the complex CuL2Cl2. This derivative has been studied by elemental analyses, molar conductance, magnetic moment measurements at different temperatures, electronic and infrared spectroscopy, thermal analyses (TG and DTG) and e.p.r. techniques. The complex has a pseudooctahedral stereochemistry, with bridging halides and with the ligands monodentate-S-bondedvia the exocyclic sulphur atom. 相似文献
905.
Giuseppe Del Re 《International journal of quantum chemistry》1981,19(6):979-984
Communication between chemists and physicists working in different domains of physical chemistry may sound like a dream, but actually it must be established in order that the whole field may develop in a more efficient way. Binding is a unifying concept whose discussion may make it possible for specialists of different extractions to profit from each other's work. When different specialists speak of binding, they have some intuitive picture in mind. Does it correspond to a unique well-defined concept, or is it just a cover for ignorance? A tentative definition is proposed as a starting point for discussion, but it is also emphasized that only from an open-minded and thorough analysis of the various interpretations it should be possible to make real progress. An example showing very clearly the relationship between the various topics is that of biopolymers, whose understanding depends on the specification of the role of a variety of binding effects, from chemisorption to charge transfer to (one-dimensional) metallic binding. 相似文献
906.
907.
Andrea M. Gasco Clara Cena Antonella Di Stilo Giuseppe Ermondi Claudio Medana Alberto Gasco 《Helvetica chimica acta》1996,79(7):1803-1817
The synthesis, structural characterization, and NO donor properties of a series of terfuroxan (= terfurazan trioxide) derivatives 1a–h and 2a–j are reported (Schemes 1 and 2). Structural assignments were confirmed principally by mass and 13C- and 1H-NMR spectroscopy. The extent and the initial rate of NO release in the presence of thiol cofactor was evaluated for each derivative. Vasodilator effects of all the terfuroxan derivatives were evaluated on endothelium-denuded strips of rat aorta precontracted with noradrenaline. Concentration-response curves were also evaluated in the presence of 10 m?M oxyhemoglobin (HbO2), a well known NO scavenger. The whole series displays high vasodilating potency; the most active terfuroxans ( 1a, b, g and 2i ) are 5–10 times as potent as glyceryl trinitrate taken as reference (see Table 3). The potency decrease observed in the presence of HbO2 agrees with the involvement of NO in the vasorelaxing action. The 4,3′:4′,4″ connection (series 1 ; furoxan numbering) gives rise to the most potent compounds. The conformational factors seem to play important roles in the activity. No clear relationship between physico-chemical properties of the substituents and potencies of derivative emerges. 相似文献
908.
Tiziana Beringhelli Gianfranco Ciani Giuseppe DAlfonso Angelo Sironi Maria Freni 《Journal of organometallic chemistry》1982,233(3):C46-C50
The novel anions [Re3H3(CO)10(μ-O2CR)]? (R = H, CH3, CF3), obtained by reaction of [Re3H4(CO)10]? with the corresponding car?ylic acids, have been characterized by IR and NMR spectra and by X-ray analysis of the formate and trifluoroacetate derivatives. They contain a triangle of rhenium atoms, with the car?ylate group diaxially bridging on the shorter ReRe edge. 相似文献
909.
Cirilli R Ferretti R Gallinella B La Torre F La Regina G Silvestri R 《Journal of separation science》2005,28(7):627-634
The enantiomeric separation of a series of imidazole analogues of Fluoxetine and Miconazole endowed with potent antifungal activity was performed using cellulose tris(4-methylbenzoate) (Chiralcel OJ) and cellulose tris(3,5-dimethylphenylcarbamate) (Chiralcel OD) as chiral stationary phases. Binary mixtures of n-hexane and alcohol as well as pure alcohols (ethanol or 2-propanol) were used as eluents. The enantiomer elution order was monitored by chiroptical detectors based on on-line optical rotation and circular dichroism measurements. For some of the compounds studied very high enantioseparation factor values (alpha > 7) on Chiralcel OJ CSP were observed. In order to study the chiroptical characteristics of the two most biologically active compounds, chromatographic resolutions were carried out on a semipreparative scale. Assignment of the absolute configuration was empirically established by comparing the CD spectra of the separated enantiomers with those obtained from the enantiomers of Miconazole. 相似文献
910.