ar—no2 bond formation by ar se reaction
Báo cáo khoa học: Bacitracin inhibits the reductive activity of protein disulfide isomerase by disulfide bond formation with free cysteines in the substrate-binding domain pptx
Ngày tải lên :
14/03/2014, 23:20
... that were used to discriminate different bacitracin analogs by MALDI-TOF ⁄ TOF MS are shown (D) The purity of each fraction was assessed by analytical RP-HPLC, with similar conditions as used for ... of this reaction were biphasic, with an initial lag phase followed by an exponential increase in turbidity In each Bacitracin forms a disulfide bond with free PDI cysteines case, the presence of ... peptides, which can be separated by RP-HPLC and characterized by MS [17] The basic structure of bacitracin consists of a cyclic peptide of seven amino acids with a linear peptide side chain of...
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Liên kết arc(=o)H hình thành thông qua phản ứng ar SE
Ngày tải lên :
15/04/2015, 09:22
... corresponding nonmetallated aromatic compounds through an Ar SE reaction (Sections 5.3.1 and 5.3.2) In addition, there are methods for preparing substituted aryl metal compounds that are isomerically pure ... especially elegant possibility for carrying out orthoselective Ar SE reactions (Section 5.3.), which otherwise is practically impossible Finally, aryl boron compounds are the best substrates for the ... radicals Ar N=N⋅ These radicals lose molecular nitrogen A highly reactive aryl radical remains, which then reacts directly or indirectly with the nucleophile Ar Ar NaNO2 NO2 H Ar Cu(II) N N CuCl Ar...
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Guanidine and guanidinium salt catalyzed enantioselective phosphorus carbon bond formation reactions 1
Ngày tải lên :
14/09/2015, 08:38
... 1.5) No reaction was observed when only KOH was used in the absence of metal oxide, which indicated that the presence of the solid support was essential for the activation of the P-H bond towards ... Et2 O O Ar H R Ar 78 77 52 Ar = o-NO2C6 H 81 selected examples Ar Ar O O P R H 2, Pd/C R O HO P O HO HN Ph NH 18 examples - 93% yield - 99% ee O Ph O P O HN Ph 78a 87% yield 98% ee Ar Ar 79a 87% ... epimerization of carbon chiral center was observed 17 Chapter H O p-Tol S N O (RO)2P (RO)2POM Ar THF, -78 oC H N S O (RO)2 P CF3 CO2H p-Tol Ar O 64 Ar 65a R = Et, Ar = Ph 65b R = iPr, Ar = p-MeOPh...
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Guanidine and guanidinium salt catalyzed enantioselective phosphorus carbon bond formation reactions 2
Ngày tải lên :
14/09/2015, 08:38
... phospha-Michael reactions catalyzed by small molecular using secondary phosphine oxides We aimed to develop an organocatalyst catalyzed phospha-Michael reaction using secondary phosphine oxides 2.3.1 ... salt has been demonstrated in several reactions such as Henry reaction4 , Strecker synthesis of α-amino acids5, Michael reaction6 , asymmetric silylation of secondary alcohols7, and electrophilic ... as substrates for this reaction (Scheme 2.5) In general, these reactions were 34 Chapter slow The reactions with various thioesters gave adducts 117a-d in excellent enantioselectivities and high...
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Guanidine and guanidinium salt catalyzed enantioselective phosphorus carbon bond formation reactions 3
Ngày tải lên :
14/09/2015, 08:38
... proton catalyst 153 was found to increase the reaction rate of a series of reactions like Diels-Alder reaction and Friedel-Crafts reaction (Scheme 3.2) Enantioselectivities, however, remained constantly ... accelerated reaction rate but high yield and high enantioselectivity was observed (entry 2) When the para-substituent was Cl or methyl group, the reaction rates were much slower reaction rate and long reaction ... phospha-Mannich reaction between secondary phosphine oxides and imines (Table 3.1, entries and 5) It was surprised that the results in terms of enantioselectivities obtained in the presence of the...
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Guanidine and guanidinium salt catalyzed enantioselective phosphorus carbon bond formation reactions 4
Ngày tải lên :
14/09/2015, 08:38
... unless otherwise stated 4.2 Preparation and characterization of P-nucleophiles 4.2.1 Preparation of phosphine oxides Phosphine oxide 125a was purchased form Sigma-Aldrich and used without 82 ... Catalyst 168 (base) was obtained (checked by 19 F NMR, no 19 F peak was observed) Catalyst 168.HBF4 and 168 with other numbers of protons were prepared by mix catalyst 168.2HBF4 and 168 (base) Stirred ... enantioselectivity of 94% ee (syn-180a) The two diastereoisomers was separated by flash chromatography (elution with DCM/ethyl acetate 10:1) 4.6.2 Characterization of phospha-Mannich reaction...
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Design of chiral indium complexes for enantioselective carbon carbon bond formation reactions
Ngày tải lên :
30/09/2015, 06:07
... involved in the reaction in any particular case Henceforth, the following sections are not about the isolation of the allylic indium species; rather these are used immediately followed 22 Fürstner, ... control of carbon-carbon bond formation in the reactions of allylmetals with aldehydes and ketones This widespread use of allylic organometallics in stereocontrolled organic synthesis appears to be ... Lewis acid catalysts for carbon-carbon bond formation and organic synthetic transformations.42 40 For Reviews , see (a) Roush, W R Comprehensive Organic Synthesis, ed by Trost, B M.; Fleming,...
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Tài liệu Chapter 6: Carbon-carbon bond formation pptx
Ngày tải lên :
23/12/2013, 07:19
... a catalyst prepared from and or could be used as base with similar results Carbon-carbon bond formation 213 The palladium complex of the dibenzofuran-based water-soluble tertiary phosphine 49 ... the presence of a base both Ar groups take part in the coupling [35] Carbon-carbon bond formation 217 Due to its stability and water-solubility sodium tetraphenylborate is a particularly convenient ... liberates benzoic acid; hence the formation of considerable amounts of the latter Carbon-carbon bond formation 231 Stoichiometric Barbier-Grignard type reactions, mediated by tin, zinc, indium or other...
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Tài liệu Báo cáo khoa học: Membrane targeting and pore formation by the type III secretion system translocon pdf
Ngày tải lên :
14/02/2014, 22:20
... Salmonella possess similar biochemical properties but are functionally distinct Mol Microbiol 42, 469–481 Harrington AT, Hearn PD, Picking WL, Barker JR, Wessel A & Picking WD (2003) Structural characterization ... ATPase from the type III secretion system Nat Struct Mol Biol 14, 131–137 Membrane targeting and pore formation by the T3SS 38 Imada K, Minamino T, Tahara A & Namba K (2007) Structural similarity ... targeting and pore formation by the T3SS P.-J Matteı et al ¨ Fig Sequence alignments of major translocator proteins that display the highest level of sequence similarity Identical residues are...
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Tài liệu Báo cáo khoa học: Insights into and speculations about snake venom metalloproteinase (SVMP) synthesis, folding and disulfide bond formation and their contribution to venom complexity pdf
Ngày tải lên :
18/02/2014, 18:20
... full-length jararhagin and 0.5% of jararhagin C [42] Thus, from this example, we can estimate that approximately only one-quarter of the jararhagin synthesized is processed to jararhagin C The ... molecular charac- Snake venom metalloproteinases and venom complexity 37 38 39 40 41 42 43 44 45 46 terization of a high molecular weight hemorrhagic metalloprotease, jararhagin, from Bothrops jararaca ... cellular mechanisms of post-translation proteolytic processing of the PIIas and PIIIbs are different Several years ago, we became intrigued by the observation that both the processed and unprocessed...
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Tài liệu Báo cáo khoa học: Models and mechanisms of O-O bond activation by cytochrome P450 A critical assessment of the potential role of multiple active intermediates in oxidative catalysis doc
Ngày tải lên :
19/02/2014, 16:20
... of carbon-centred radicals derived from a diverse set of substrates are on the order of about 10)10 s [98] Moreover, the randomness of the apparent intramolecular KIEs for unrearranged and rearranged ... out owing to insensitivity of the reaction toward radical scavengers, whereas blockage of turnover by cyanide hinted at an iron-based mechanism [116] The sum of these ndings raised serious questions ... catalyzed by toluene dioxygenase from Pseudomonas putida Biochemistry 27, 13601367 207 Resnick, S.M., Lee, K & Gibson, D.T (1996) Diverse reactions catalyzed by naphthalene dioxygenase from Pseudomonas...
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Báo cáo khoa học: Cytoglobin conformations and disulfide bond formation pdf
Ngày tải lên :
15/03/2014, 11:20
... Cytoglobin conformations and disulfide bond formation A Results and Discussion Quaternary structure analysis of human Cygb by size exclusion chromatography with multi-angle laser light scattering (SEC-MALLS) ... form an internal S–S bond, displays a faster replacement reaction; however, heterogeneity is observed, indicating the presence of two protein conformations The rapid phase arising from the competition ... of formation of an intramolecular disulfide bridge The formation of an intermolecular disulfide bridge was observed in mass spectrometry, but represents only a small fraction of the Cygb preparation...
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Báo cáo khoa học: Inactivation of tyrosine phenol-lyase by Pictet–Spengler reaction and alleviation by T15A mutation on intertwined N-terminal arm docx
Ngày tải lên :
16/03/2014, 12:20
... indole-lyase (TNA; PDB entry: 1AX4) and aspartate aminotransferases (AspAT; PDB entry: 1ARI) [16–18] In porcine cytosolic aspartate aminotransferase (AspAT), the N-terminal arm protruding toward the large ... has a 50% sequence identity with the tryptophanase from P vulgaris, which degrades tryptophan to indole, ammonia, and pyruvate [14,25] The secondary, tertiary, and quaternary structures are also ... enzymes, aromatic decarboxylases, by l-DOPA [10,23], this is the first time the rapid inactivation of TPL has been explained based on a Pictet–Spengler reaction Consistent with the observation...
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Báo cáo khoa học: Abstract P1 – FEBS Datta Plenary Lectureship Award P1-001 Peptide bond formation, cotranslational folding and antibiotics synergism docx
Ngày tải lên :
16/03/2014, 22:20
... era T Jenuwein Research Institute of Molecular Pathology (IMP), The Vienna Biocenter, Vienna, Austria E-mail: jenuwein@imp.univie.ac.at The last years were highlighted by the landmark description ... and genome stability The implications of epigenetic research for human biology and disease, including stem cells, cancer and aging are far-reaching and will form a modern foundation to explore ... nucleus M Carmo-Fonseca Institute of Molecular Medicine, University of Lisbon, Lisbon, Portugal E-mail: carmo.fonseca@fm.ul.pt The spliceosome is a dynamic RNA-protein macromolecular machine...
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Báo cáo Y học: Disul®de bond formation through Cys186 facilitates functionally relevant dimerization of trimeric hyaluronan-binding protein 1 (HABP1)/p32/gC1qR docx
Ngày tải lên :
17/03/2014, 17:20
... Materials EAH±Sepharose 4B, Superose columns, Sephadex G-25 and molecular mass markers were obtained from Pharmacia Biotech Inc (Uppsala, Sweden) The Protoblot Western-blot system was purchased from ... molecular mass standards under the above conditions The molecular mass (Mr) of standards indicated by arrows is shown in the inset and numbered 1, 2, 3, and 5, respectively The peaks marked I, ... relative molecular mass of nearly 70 kDa However, a smear at 20±25 kDa was consistently observed, which represents uncross-linked HABP1 monomer corresponding to the sequence-derived molecular mass...
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multilayer tio2 – nanotube formation by two-step anodization
Ngày tải lên :
20/03/2014, 13:05
... layer is confirmed by Fig 4B Figure 4C shows a high-resolution TEM image of the tube bottom of the second layer Clearly, an amorphous structure is present as confirmed by selected area diffraction ... second layer starts at the bottom of the first tubes by narrow channels being formed in the early stages Further, we show that the thickness of these second layers can be in the range of several micrometers, ... steps in the formation of the second tubular layer during the second anodization step Downloaded 21 Jul 2008 to 159.226.100.134 Redistribution subject to ECS license or copyright; see http://www.ecsdl.org/terms_use.jsp...
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Báo cáo khoa học: On peptide bond formation, translocation, nascent protein progression and the regulatory properties of ribosomes ppt
Ngày tải lên :
23/03/2014, 17:22
... short or loosely placed analogs are positioned with orientations requiring conformational rearrangements in order to participate in peptide bond formation [3,5,6] These rearrangements are bound ... sequence of SecM includes a sequence motif FXXXXWIXXXXGIRAGP that, in the absence of the protein export system, causes elongation arrest during translation of SecM in E coli This particular sequence ... case of the archaeon H marismortui [4], requires significantly higher concentrations than those used clinically Hence, in this critical aspect, H marismortui resembles eukaryotes more than prokaryotes...
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Báo cáo Y học: Suppression of apolipoprotein C-II amyloid formation by the extracellular chaperone, clusterin potx
Ngày tải lên :
24/03/2014, 04:21
... modeling by a superposition of sedimentation profiles of ideal nondiffusing particles [30] A regularization parameter of p ¼ 0.95, and a buffer density of 1.01 gÆmL)1 was used The nonsedimenting baselines ... aggregates, the sedimentation boundaries at different time points were analyzed to obtain ls ) g*(s) sedimentation coefficient distributions The method is based on direct linear least-squares boundary modeling ... amyloid present [6,18] This change in fluorescence was used to monitor amyloid formation by apoC-II in the presence of various concentrations of clusterin (Fig 1) For apoC-II alone, amyloid formation...
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Báo cáo khoa học: Protein folding and disulfide bond formation in the eukaryotic cell pptx
Ngày tải lên :
29/03/2014, 22:21
... cytoplasm itself is rare Instead, the reductive ‘antioxidant’ environment is (partly) maintained by the oxidoreductase thioredoxin R Hartmann-Petersen (Copenhagen, Denmark) discussed a thioredoxin-related ... disulfide bonds, and how and when these different activities come into play is the subject of much current research There are also a surprisingly large number of thiol– disulfide oxidoreductase and ... Tim proteins J Biol Chem 284, 6818–6825 28 Thomsen M, Hansen B, Nilsson P, Nowak J, Johansen P, Thomsen P & Christiansen J (1994) Pharmacological characterization of a biosynthetic trisulfide-containing...
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Báo cáo khoa học: Monitoring the prevention of amyloid fibril formation by a-crystallin Temperature dependence and the nature of the aggregating species pdf
Ngày tải lên :
30/03/2014, 04:20
... mass increased by and the density decreased 0.02 ngÆmm)2 by 0.0072 gÆcm)3 After 2.5 h, the thickness increased by 0.212 nm, the mass increased by 0.05 ngÆmm)2 and the density decreased by 0.0167 ... temperature (Fig 2A,B) However, as assessed by TFT binding, the presence of a-crystallin significantly suppressed fibril formation by j-casein (Fig 2A,B) At 30 °C, the fibril formation rate was slowest and ... the start of the experiment By the end of the measurement, the thickness had increased by 0.342 nm, the mass had increased by 0.10 ngÆmm)2 and the density had decreased by 0.024 gÆcm)3 By contrast,...
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