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951.
Classification for enzymes is a prerequisite for understanding their function. Here, an automatic enzyme identifier based on support vector machine (SVM) with feature vectors from protein functional domain composition was built to identify enzymes and further a classifier to classify enzymes into six different classes: oxidoreductase, transferase, hydrolase, lyase, isomerase and ligase. Jackknife cross-validation test was adopted to evaluate the performance of our classifier. The 86.03% success rate achieved for enzyme/non-enzyme identification and 91.32% for enzyme classification, which is much better than that of the BLAST and PSI-BLAST based method, also outperforms several existed works. The results indicate that protein functional domain composition is able to capture the major features which facilitate the identification/classification of proteins, thus demonstrating that our predictor could be a more effective and promising high-throughput method in enzyme research. Moreover, a web-based software Enzyme Classification System (ECS) for identification as well as classification of enzymes can be accessed at: http://pcal.biosino.org/. 相似文献
952.
We developed an intelligent polymerized crystalline colloidal array (IPCCA) photonic crystal sensing material which reversibly
senses the organophosphate compound methyl paraoxon at micromolar concentrations in aqueous solutions. A periodic array of
colloidal particles is embedded in a poly-2-hydroxyethylacrylate hydrogel. The particle lattice spacing is such that the array
Bragg-diffracts visible light. We utilize a bimodular sensing approach in which the enzyme organophosphorus hydrolase (OPH)
catalyzes the hydrolysis of methyl paraoxon at basic pH, producing p-nitrophenolate, dimethylphosphate, and two protons. The protons lower the pH and create a steady-state pH gradient. Protonation
of the phenolates attached to the hydrogel makes the free energy of mixing of the hydrogel less favorable, which causes the
hydrogel to shrink. The IPCCA’s lattice constant decreases, which blueshifts the diffracted light. The magnitude of the steady-state
diffraction blueshift is proportional to the concentration of methyl paraoxon. The current detection limit is 0.2 μmol methyl
paraoxon per liter. 相似文献
953.
The potential of using ensiling, with and without supplemental enzymes, as a cost-effective pretreatment for bioethanol production from agricultural residues was investigated. Ensiling did not significantly affect the lignin content of barley straw, cotton stalk, and triticale hay ensiled without enzyme, but slightly increased the lignin content in triticale straw, wheat straw, and triticale hay ensiled with enzyme. The holocellulose (cellulose plus hemicellulose) losses in the feedstocks, as a result of ensiling, ranged from 1.31 to 9.93%. The percent holocellulose loss in hays during ensiling was lower than in straws and stalks. Ensiling of barley, triticale, wheat straws, and cotton stalk significantly increased the conversion of holocellulose to sugars during subsequent hydrolysis with two enzyme combinations. Enzymatic hydrolysis of ensiled and untreated feedstocks by Celluclast 1.5 L-Novozyme 188 enzyme combination resulted in equal or higher saccharification than with Spezyme CP-xylanase combination. Enzyme loadings of 40 and 60 FPU/g reducing sugars gave similar sugar yields. The percent saccharification with Celluclast 1.5 L-Novozyme 188 at 40 FPU/g reducing sugars was 17.1 to 43.6%, 22.4 to 46.9%, and 23.2 to 32.2% for untreated feedstocks, feedstocks ensiled with, and without enzymes, respectively. Fermentation of the hydrolysates from ensiled feedstocks resulted in ethanol yields ranging from 0.21 to 0.28 g/g reducing sugars. 相似文献
954.
955.
Nathalie Payre Sylvain Cottaz Claire Boisset Redouane Borsali Birte Svensson Bernard Henrissat Hugues Driguez 《Angewandte Chemie (International ed. in English)》1999,38(7):974-977
Heterobifunctional ligands that bind at the same time to the catalytic domain and to the starch-binding domain of glucoamylase induce a conformational change of the protein, as shown by dynamic light scattering. The ligands consist of acarbose and β-cyclodextrin linked together by oligoethylene glycols of variable length (see the schematic diagram). 相似文献
956.
Jacob Overgaard Birgit Schitt Finn K. Larsen Arthur J. Schultz John C. MacDonald Bo B. Iversen 《Angewandte Chemie (International ed. in English)》1999,38(9):1239-1242
Low-barrier hydrogen bond (LBHB) involvement in enzyme catalysis is examined by analysis of experimental nuclear and electron densities of a model compound for the catalytic triad in serine proteases (shown schematically), which is based on a cocrystal of betaine, imidazole, and picric acid. The three short, strong N−H⋅⋅⋅O hydrogen bonds in the structure have varying degrees of covalent bonding contributions suggesting a gradual transition to the LBHB situation. 相似文献
957.
Thomas Kolter Konrad Sandhoff 《Angewandte Chemie (International ed. in English)》1999,38(11):1532-1568
Glycolipids such as ganglioside GM1 are involved in the building of carbohydrate layers on the surface of living cells. The investigation of the metabolism of this class of compounds gives insight into human diseases, novel signal transduction processes, and the epidermal water permeability barrier. 相似文献
958.
Manfred T. Reetz Michael H. Becker Heinz-Werner Klein Detlef Stckigt 《Angewandte Chemie (International ed. in English)》1999,38(12):1758-1761
About 1000 catalytic or stoichiometric asymmetric reactions of racemic compounds or prochiral substrates bearing enantiotopic groups can be analyzed per day. In this highly efficient method the enantioselectivity is determined by electrospray ionization mass spectrometry using isotopically labeled substrates. The picture shows the mass spectrum of the mixture obtained upon hydrolysis of 1 to afford the pseudo-enantiomeric products 2 and 3 . 相似文献
959.
960.