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11.
Roque Bru Jose M. López-Nicolás Estrella Núñez-Delicado Dolores Nortes-Ruipérez Alvaro Sánchez-Ferrer Francisco Garciá-Carmona 《Applied biochemistry and biotechnology》1996,61(1-2):189-198
The capability of cyclodextrins to enhance greatly the solubility in water of poorly water-soluble substances makes them an
ideal alter native for investigating the expression of enzyme activity with such substrates in aqueous solution. This capability
is demonstrated by using soybean lipoxygenase with linoleic acid/β-cyclodextrin and di ethylstilbestrol/γ-cyclodextrin, and
cholesterol oxidase with choles terol/methyl-β-cyclodextrin. 相似文献
12.
Summary The use of capillary electrophoresis for the analysis of selected flavonols present in fruit juices and wines (kaempferol-3-rutinoside,
rutin, avicularin, quercitrin, isoquercitrin, isorhamnetin, kaempferol and quercetin) was explored, and the effect of pH and
temperature on the separation studied. The method had good reproducibility and analyses were carried out in less than 10 minutes. 相似文献
13.
Ferran Sanz Francesc Manaut Jesús Rodríguez Estrella Lozoya Elena López-de-Briñas 《Journal of computer-aided molecular design》1993,7(3):337-347
Summary MEPSIM is a computational system which allows an integrated computation, analysis, and comparison of molecular electrostatic potential (MEP) distributions. It includes several modules. Module MEPPLA supplies MEP values for the points of a grid defined on a plane which is specified by a set of three points. The results of this program can easily be converted into MEP maps using third-parties graphical software. Module MEPMIN allows to find automatically the MEP minima of a molecular system. It supplies the cartesian coordinates of these minima, their values, and all the geometrical relationships between them (distances, angles, and dihedral angles). Module MEPCOMP computes a similarity coefficient between the MEP distributions of two molecules and finds their relative position that maximizes the similarity. Module MEPCONF performs the same process as MEPCOMP, considering not only the relative position of both molecules but also a conformational degree of freedom of one of them. The most recently developed module, MEPPAR, is another modification of MEPCOMP in order to compute the MEP similarity between two molecules, but only taking into account a particular plane. The latter module is particularly useful to compare MEP distributions generated by systems of aromatic rings. MEPSIM can use several wavefunction computation approaches to obtain MEP distributions. MEPSIM has a menu type interface to simplify the following tasks: creation of input files from output files of external programs (GAUSSIAN and AMPAC/MOPAC), setting the parameters for the current computation, and submitting jobs to the batch queues of the computer. MEPSIM has been coded in FORTRAN and its current version runs on VMS/VAX computers. 相似文献
14.
Structural and thermal properties of all-trans lycopene are described in the present paper. Different crystalline lycopene samples obtained from fermentation process and recrystallized lycopene were analyzed. Structural properties (NMR, mass spectrometry and powder X-ray diffraction) of lycopene were clarified with recent techniques. High purity sample analysis by differential scanning calorimetry was used to study thermal behavior of pure lycopene and with traces of isomers. But also this was correlated with HPLC method for determine lycopene purity and isomers in low proportion. 相似文献
15.
José Manuel López-Nicolás Estrella Núñez-Delicado Antonio José Pérez-López Álvaro Sánchez-Ferrer Francisco García-Carmona 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):219-222
Polyphenol oxidase causes enzymatic browning by catalyzing natural phenolic compounds to quinones. Subsequent nonenzymatic
oxidative polymerization reactions form brown, black, or red pigments (melanins). Many methods can be shown experimentally
to diminish or prevent browning but are not all applicable for food use. In this work, the colour of fresh apple juice was
evaluated in the presence of maltosyl-β-CD, compound that complex polyphenol oxidases substrates. The effectiveness of CD
as browning inhibitor was determined by the difference between the colours observed in the CD-treated sample and the controls,
using the colour space CIE- L, a*, b* system. We have kinetically modelled apple juice enzymatic browning in the absence and
presence of maltosyl-β-CD. The complexation constant between the mixtures of diphenols present in apple juice and maltosyl-β-CD
was calculated (Kc = 4.09 mM−1). 相似文献
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Irene Díaz-Moreno Francisco J. Muoz-Lpez Estrella Frutos-Beltrn Miguel A. De la Rosa Antonio Díaz-Quintana 《Bioelectrochemistry (Amsterdam, Netherlands)》2009,77(1):43-52
Many fleeting macromolecular interactions, like those being involved in electron transport, are essential in biology. However, little is known about the behaviour of the partners and their dynamics within their short-lived complex. To tackle such issue, we have performed molecular dynamics simulations on an electron transfer complex formed by plastocyanin and cytochrome f from the cyanobacterium Phormidium laminosum.Besides simulations of the isolated partners, two independent trajectories of the complex were calculated, starting from the two different conformations in the NMR ensemble. The first one leads to a more stable ensemble with a shorter distance between the metal sites of the two partners. The second experiences a significant drift of the complex conformation. Analyses of the distinct calculations show that the conformation of cytochrome f is strained upon binding of its partner, and relaxes upon its release. Interestingly, the principal component analysis of the trajectories indicates that plastocyanin displays a concerted motion with the small domain of cytochrome f that can be attributed to electrostatic interactions between the two proteins. 相似文献
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Nontargeted GC–MS approach for volatile profile of toasting in cherry,chestnut, false acacia,and ash wood 下载免费PDF全文
Brígida Fernández de Simón Miriam Sanz Estrella Cadahía Enrique Esteruelas Angel María Muñoz 《Journal of mass spectrometry : JMS》2014,49(5):353-370
By using a nontargeted GC–MS approach, 153 individual volatile compounds were found in extracts from untoasted, light toasted and medium‐toasted cherry, chestnut, false acacia, as well as European and American ash wood, used in cooperage for aging wines, spirits and other beverages. In all wood types, the toasting provoked a progressive increase in carbohydrate derivatives, lactones and lignin constituents, along with a variety of other components, thus increasing the quantitative differences among species with the toasting intensity. The qualitative differences in the volatile profiles allow for identifying woods from cherry (being p‐anisylalcohol, p‐anisylaldehyde, p‐anisylacetone, methyl benzoate and benzyl salicylate detected only in this wood), chestnut (cis and trans whisky lactone) and false acacia (resorcinol, 3,4‐dimethoxyphenol, 2,4‐dihydroxy benzaldehyde, 2,4‐dihydroxyacetophenone, 2,4‐dihydroxypropiophenone and 2,4‐dihydroxy‐3‐methoxyacetophenone), but not those from ash, because of the fact that all compounds present in this wood are detected in at least one other. However, the quantitative differences can be clearly used to identify toasted ash wood, with tyrosol being most prominent, but 2‐furanmethanol, 3‐ and 4‐ethylcyclotene, α‐methylcrotonolactone, solerone, catechol, 3‐methylcatechol and 3‐hydroxybenzaldehyde as well. Regarding oak wood, its qualitative volatile profile could be enough to distinguish it from cherry and acacia woods, and the quantitative differences from chestnut (vanillyl ethyl ether, isoacetovanillone, butirovanillone, 1‐(5‐methyl‐2‐furyl)‐2‐propanone and 4‐hydroxy‐5,6‐dihydro‐(2H)‐pyran‐2‐one) and ash toasted woods. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
20.
Determination of Abamectin Residues in Avocados by Microwave-Assisted Extraction and HPLC with Fluorescence Detection 总被引:1,自引:0,他引:1
Javier Hernández Borges Lidia M. Ravelo-Pérez Estrella M. Hernández-Suárez Aurelio Carnero Miguel Ángel Rodríguez-Delgado 《Chromatographia》2008,67(1-2):69-75
In this article a new analytical method for the confirmation and quantification of abamectin residues in avocados is described.
The method allows a fast analysis of abamectin homologues using microwave assisted extraction (MAE), solid-phase extraction
(SPE) and high-performance liquid chromatography (HPLC) with fluorescence (FL) detection using trifluoroacetic anhydride (TFAA)
and N-methylimidazole (NMIM) as derivatizing agents. The mobile phase consisted of water, methanol and acetonitrile (5:47.5:47.5
v/v/v) and was pumped at a rate of 1.1 mL min−1 (isocratic elution). Homogenized avocado samples were extracted once with 20 mL acetonitrile:water 4:1 (v/v) in a microwave oven for 26 min at 700 W with a maximum temperature of 80 °C. MAE operational parameters were optimized by
means of an experimental design. Extracts were cleaned using C18 SPE cartridges. Average recoveries of the method at four spiked levels (0.005, 0.01, 0.10 and 1.0 mg kg−1) were found to be in the range 90–100% with good precision (RSD < 12%). The limits of detection (LODs) and quantification
(LOQs) of the whole method were 0.001 and 0.003 mg kg−1, respectively, which are lower than the maximum residue limit (MRL) established by the Spanish and the European legislation
in avocados (0.01 mg kg−1). Several avocado samples previously treated with the pesticide were also analyzed. 相似文献