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Lee K B - - 2006
Alpha-emitting 238Pu and 241Am sources on stainless steel substrates have been prepared using a new electrodeposition method based on an ammonium oxalate-ammonium sulfate electrolyte containing diethyl triamino pentaacetic acid. The deposition yield is determined by measuring the activity of the sources using a high-efficiency 2pi alpha proportional counter and a ...
Houk Ronald J T - - 2006
[reaction: see text] The dependence of acidity on Li+ coordination geometry to alpha-carbon acids is investigated by generating potential energy surfaces of Li+ complexation with acetaldehyde and its respective enolate. The global minimum for the enolate complex shows significant Li+-pi-system coordination to both oxygen and the alpha-carbon. The gas-phase acidity ...
Hargrave Jonathan D - - 2006
The cationic rhodium complex [Rh(cod)2][BF4] effectively catalyses the 1,4-addition of organotrialkoxysilanes to alpha-substituted acrylic esters. The reactions are promoted by heating in an oil-bath or more conveniently in a microwave reactor allowing rapid access to a useful range of functionalised products including 2-alkyl succinates and alpha-amino acid derivatives.
Bou Ricard - - 2006
The effects of dietary alpha-tocopheryl acetate (alpha-TA) doses (75, 150, and 225 mg/kg) and the duration of this supplementation (0, 10, 21, 32, and 43 days prior to slaughter) on fatty acid composition, alpha-tocopherol content, and oxidative status were studied either in raw or in cooked dark chicken meat with ...
Bleiholder Christian - - 2006
The proton affinities (PA) of the 20 naturally occurring alpha-amino acids (AA) have been determined computationally by means of density functional theory (DFT) and high-level G2(MP2) calculations. These theoretical PAs, together with data that have appeared since 1997 in the literature, are used to validate the most reasonable currently available ...
Moulin M - - 2006
Higher plant responses to abiotic stresses are associated with physiological and biochemical changes triggering a number of metabolic adjustments. We focused on L-lysine catabolism, and have previously demonstrated that degradation of this amino acid is osmo-regulated at the level of lysine-ketoglutarate reductase (LKR, EC 1.5.1.8) and saccharopine dehydrogenase (SDH, EC ...
Müller Tina A - - 2006
Alpha-ketoglutarate-dependent (R)-dichlorprop dioxygenase (RdpA) and alpha-ketoglutarate-dependent (S)-dichlorprop dioxygenase (SdpA), which are involved in the degradation of phenoxyalkanoic acid herbicides in Sphingomonas herbicidovorans MH, were expressed and purified as His6-tagged fusion proteins from Escherichia coli BL21(DE3)(pLysS). RdpA and SdpA belong to subgroup II of the alpha-ketoglutarate-dependent dioxygenases and share the specific ...
Czerwiñska MaƂgorzata - - 2006
The inversion of the keto-enol stability order of dialuric acid on ionization was calculated and verified experimentally. The radical cations in both forms were characterized. The spectrum of the keto form was observed upon direct ionization of dialuric acid under matrix conditions, whereas the enol form was formed upon a ...
Kumar T Santhosh - - 2006
A convergent route to a new class of locked nucleic acids, i.e., 2'-amino-alpha-L-LNA, has been developed. The optimized synthetic route to the corresponding phosphoramidite building block of thymine proceeds in 4% overall yield over 15 steps from the starting diol. Crucial synthetic steps include (a) introduction of a C2-azido group ...
Burger K - - 2006
5-Benzyloxy-4-trifluoromethyl-1,3-oxazoles, obtained from 5-fluoro-4-trifluoromethyloxazoles and benzyl alcohols, are capable for rearrangements. A 1,3 shift of a benzyl group is the key step of a new general route toward alpha-trifluoromethyl substituted aromatic and heteroaromatic amino acids, demonstrating that 5-fluoro-4-trifluoromethyl-1,3-oxazole is a synthetic Tfm-Gly equivalent. On reaction with benzpinacol partially fluorinated oxazoles ...
Meyer Udo - - 2006
For the second-generation asymmetric synthesis of the trans-tris(homoglutamic) acids via Strecker reaction of chiral ketimines, the cyanide addition as the key stereodifferentiating step produces mixtures of diastereomeric alpha-amino nitrile esters the composition of which is independent of the reaction temperature and the type of the solvent, respectively. The subsequent hydrolysis ...
Panneerselvam Kavin S - - 2006
This article has been removed consistent with Elsevier Policy on Article Withdrawal. The Publisher apologies for any inconvenience this may cause.
Landwehr Marco - - 2006
Here we report that an engineered microbial cytochrome P450 BM-3 (CYP102A subfamily) efficiently catalyzes the alpha-hydroxylation of phenylacetic acid esters. This P450 BM-3 variant also produces the authentic human metabolite of buspirone, R-6-hydroxybuspirone, with 99.5% ee.
Hamberg Mats - - 2006
3-Oxalinolenic acid (3-oxa-9(Z),12(Z),15(Z)-octadecatrienoic acid or (6(Z),9(Z),12(Z)-pentadecatrienyloxy)acetic acid) was synthesized from 5(Z),8(Z),11(Z),14(Z),17(Z)-eicosapentaenoic acid by a sequence involving the C15 aldehyde 3(Z),6(Z),9(Z),12(Z)-pentadecatetraenal as a key intermediate. Conversion of the aldehyde by isomerization and two steps of reduction afforded 6(Z),9(Z),12(Z)-pentadecatrienol, which was coupled to bromoacetate to afford after purification by HPLC >99%-pure 3-oxalinolenic ...
Zhang Haoyue - - 2006
PURPOSE: The study's purpose was to compare acarbose and maltose as inhibitors of maltase-glucoamylase activity for determining acid alpha-glucosidase activity in dried blood spot specimens for early identification of patients with infantile Pompe disease, a severe form of acid alpha-glucosidase deficiency. METHODS: Acid alpha-glucosidase activities in dried blood spot extracts ...
May James M - - 2006
To assess the disulfide reduction capacity of intact cells, EA.hy926 endothelial cells were incubated with alpha-lipoic acid in the presence of 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB). Alpha-lipoic acid was reduced within cells to dihydrolipoic acid, which could be quantified upon efflux from the cells as reduction of DTNB. Uptake of both alpha-lipoic ...
Ali Hasenah - - 2006
Extracts of six selected Malaysian plants with a reputation of usefulness in treating diabetes were examined for alpha-amylase inhibition using an in vitro model. Inhibitory activity studied by two different protocols (with and without pre-incubation) showed that Phyllanthus amarus hexane extract had alpha-amylase inhibitory properties. Hexane and dichloromethane extracts of ...
Ando Hiromune - - 2006
A synthetic study on alpha-(1-->4) and alpha-(1-->8)-fucosylation of sialic acid is reported, with the ultimate aim being the total assembly of the glycan portion of HPG-series gangliosides. In both types of fucosylations, the combination of a phenylthio fucosyl donor and a 1,5-lactamized acceptor provided high-yielding glycosylations to afford alpha-fucosyl-sialic acid ...
Shen Jun - - 2006
Many enzymes catalyze fast exchange between a small pool and a large pool in vivo. For example, aspartate aminotransferase catalyzes fast exchanges between alpha-ketoglutarate and glutamate and between oxaloacetate and aspartate, which can be detected using in vivo(13)C MRS while saturating alpha-carbons of the keto acids. Unlike in the traditional ...
Gatto Gregory J GJ - - 2006
Rapamycin, FK506, and FK520 are immunosuppressant macrolactone natural products comprised of predominantly polyketide-based core structures. A single nonproteinogenic pipecolic acid residue is installed into the scaffold by a nonribosomal peptide synthetase that also performs the subsequent macrocyclization step at the carbonyl group of this amino acid. It has been assumed ...
Christiansen Bolette - - 2006
The goldfish odorant receptor 5.24 is a member of family C of G protein-coupled receptors and is closely related to the human receptor GPRC6A. Receptor 5.24 has previously been shown to have binding affinity for L-alpha-amino acids, especially the basic amino acids arginine and lysine. Here we report the agonist ...
Dickins Rachel S - - 2006
A water-soluble, enantiopure lanthanide complex, SSS-[Ln x L3], has been assessed as an effective chiral derivatizing agent for the determination of the enantiomeric purity of alpha-hydroxy acids in aqueous solution. The complex displays superior chemical shift non-equivalence (DeltaDeltadelta approximately 2-11 ppm) for the diastereomeric resonances of interest compared to lanthanide ...
Maes Veronique - - 2006
Two new 99mTc-labeled neurotensin(8-13) analogues containing the retro-N(alpha)-carboxymethyl-histidine ((N(alpha)His)Ac) chelator were synthesized as potential radiopharmaceuticals for visualization of pancreatic carcinoma. To improve the pharmacokinetic properties, (N(alpha)His)Ac-Arg-NMeArg-Pro-Tyr-Tle-Leu (NT-XII), which is metabolically stabilized at two positions, was further modified. Shikimic acid (3,4,5-trihydroxy-1-cyclohexene-1-carboxylic acid) was introduced to obtain a more hydrophilic peptide (NT-XVIII), ...
Roy St?phanie - - 2006
Stereocontrolled formation of tertiary or quaternary chiral carbons bearing nitrogen was achieved using the [3,3]-sigmatropic rearrangement of cyanate to isocyanate as a key element. A short and highly selective sequence of reactions, starting from p-menthane-3-carboxaldehyde, was developed leading to alpha,alpha-dialkylated alpha-amino acids or N-heterocycles, depending on the method of cleavage ...
Martínez-Cuesta M Carmen - - 2006
Amino acid catabolism is mainly initiated in Lactococcus lactis by a transamination reaction that leads to the formation of alpha-keto acids. In addition, a novel alpha-keto acid decarboxylase enzyme, rare in lactic acid bacteria, responsible for the conversion of alpha-keto acids into aldehydes has been reported in L. lactis IFPL730. ...
Pumera Martin - - 2006
Semi-empirical quantum mechanics calculations using AM1 (Austin Method 1) were carried out for various host-guest combinations of alpha-cyclodextrin and mono-halogen benzoic acids. The energetically favorable inclusion structures were identified. The AM1 results show that alpha-cyclodextrin complexes with mono-halogen benzoic acid acids (where the halogen is chlorine, bromide, iodine) as guest ...
Funchal Cláudia - - 2006
Accumulation of the branched-chain alpha-keto acids (BCKA), alpha-ketoisocaproic acid (KIC), alpha-keto-beta-methylvaleric acid (KMV), and alpha-ketoisovaleric acid (KIV) and their respective branched-chain alpha-amino acids (BCAA) in tissues and biological fluids is the biochemical hallmark of patients affected by the neurometabolic disorder known as maple syrup urine disease (MSUD). Considering that brain ...
Kakkar Rita - - 2006
Pyruvic acid and its isomers, including the enol tautomers and enantiomeric lactone structures, have been investigated at the B3LYP/6-311 + + G(3df,3pd) level, and it is found that a keto form with trans C(methyl)C(keto)C(acid)O(hydroxyl) and cis C(keto)C(acid)OH, and with one methyl hydrogen in a synperiplanar position with respect to the ...
Song Chuanjun - - 2006
[reaction: see text] Reactions between alpha-substituted unsaturated carboxylic acids 20 and N-tosylpyrroles [14, 23] in the presence of trifluoroacetic anhydride result in smooth alpha-acylation of the pyrrole, followed by Nazarov cyclization to give 50-80% yields of cyclopenta[b]pyrroles. The presence of an alpha-substituent in the unsaturated acid appears to be mandatory.
Martinková Miroslava - - 2006
A stereoselective approach has been developed to the new sugar amino acid and potential potent turn mimic 5-O-(tert-butyldimethylsilyl)-3-deoxy-1,2-O-isopropylidene-3-methoxycarbonylamino-alpha-D-xylofuranose 3-C-carboxylic acid (12), via the [3,3]-sigmatropic rearrangement of allylic thiocyanates (Z)-6 and (E)-7, prepared from D-xylose. The synthesis of a new dipeptide 13 is also described.
Perpète Philippe - - 2006
The catabolism of methionine to methionol and methanethiol in Saccharomyces cerevisiae was studied using (13)C NMR spectroscopy, GC-MS, enzyme assays and a number of mutants. Methionine is first transaminated to alpha-keto-gamma-(methylthio)butyrate. Methionol is formed by a decarboxylation reaction, which yields methional, followed by reduction. The decarboxylation is effected specifically by ...
Terry Claire - - 2006
Cryopreservation of human hepatocytes is important for the treatment of liver disease by hepatocyte transplantation and also for the use of hepatocytes as an in vitro model of the liver. One factor in the success of cryopreservation is the quality of cells before freezing. Preincubation of hepatocytes with cytoprotective compounds ...
Gonzalez-Perez Oscar - - 2006
Alpha-lipoic acid and vitamin E have synergistic effects, as determined in models of oxidant radical lesions. This review summarizes recent findings showing that the combination of alpha-lipoic acid plus vitamin E has beneficial effects in reducing oxidative damage in ischemic or other oxidation-related pathological events. Both antioxidants are common in ...
Aoki Satoko - - 2006
The alpha-anomer form of sulfoquinovosyl-monoacylglycerol with a saturated C18 fatty acid (alpha-SQMG-C(18:0)) is a natural sulfolipid that is a clinically promising antitumor agent. It forms vesicles, micelles or an emulsion in water, depending on several physicochemical conditions. The type of aggregate formed appears to strongly influence the bioactivity level. Thus, ...
Palecz Bartlomiej - - 2005
Dissolution enthalpies of L-alpha-proline, L-alpha-tyrosine, L-alpha-tryptophan, L-alpha-histidyne, L-alpha-arginine, L-alpha-lysine, L-aspartic acid, and L-alpha-glutamic acid in aqueous solutions of urea have been measured by calorimetry at a temperature of 298.15 K. The values of dissolution enthalpy were used to determine enthalpic heterogeneous pair interaction coefficients between the zwitterions of the natural ...
Okumiya Toshika - - 2006
We have established a new method for the enzymatic diagnosis of glycogen storage disease type II (Pompe disease or acid maltase deficiency) using mixed leukocytes. The method employs glycogen and 4-methylumbelliferyl-alpha-D-glucopyranoside (4MU-alphaGlc) as substrates for measuring the lysosomal acid alpha-glucosidase (acid alphaGlu) activity, and incorporates acarbose to eliminate the interference ...
Naydenova Emilia - - 2006
Novel alpha-aminophosphonic acids are synthesized reacting 1,3-oxazolidin-2-one derivatives with formaldehyde and phosphorus trichloride. Treatment of N-(phosphonomethyl)oxazolidinones with aqueous NaOH gave the expected alpha-aminophosphonic acids. The oxidation of (2-hydroxy-1,1-dimethylethylamino)methyl phosphonic acid in the presence of CdO and water resulted in N-phosphonomethyl-2-methyl-1-propanoic acid. Their structures were proved by means of IR, 1H, ...
Margiotta Nicola - - 2005
Synthetic amino acids such as fluorinated alpha-amino acids are currently actively investigated for their biological activity. Herein, we report on the synthesis and characterization of platinum complexes containing an N,O-chelated pure enantiomer of alpha-trifluoromethylalanine (alpha-Tfm-Ala). The compounds are either anionic, K[PtCl2(alpha-Tfm-Ala)], or cationic, [PtAm2(alpha-Tfm-Ala)](NO3) (Am2= (NH3)2, ethylendiamine (en), 1,10-phenanthroline (phen), ...
Mazaleyrat Jean-Paul - - 2005
An induced axial chirality in the biphenyl core of the 2',1':1,2;1'',2'':3,4-dibenzcyclohepta-1,3-diene-6-amino-6-carboxylic acid (Bip) residue, a conformationally labile, atropoisomeric, C(alpha)-tetrasubstituted alpha-amino acid, was observed by CD and (1)H NMR spectroscopic techniques in the linear dipeptides Boc-Bip-Xaa*-OMe where Boc=tert-butoxycarbonyl, OMe=methoxy, and Xaa*=D- and/or L-Ala, -Val, -Leu, -Phe, -(alphaMe)Val and -(alphaMe)Leu. Chiral induction ...
Cheng Mao-Sheng - - 2006
A facile synthetic approach toward oleanolic acid glycoside bearing alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl moiety, a unique oligosaccharide that strongly induces antitumor activity of oleanane-type triterpenoid saponins, was developed. Based on this approach beta-hederin (oleanolic acid 3-O-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranoside) was efficiently prepared from oleanolic acid through stepwise glycosylation in linear eight steps with 52% overall yield, ...
Katritzky Alan R - - 2005
[Structure: see text]. Reactions of readily available N-(alkyl-, aryl-, and heteroarylsulfonyl)benzotriazoles 3a-h with diverse nitriles, reactive heteroaromatics, alkylheteroaromatics, sulfones, and esters produced alpha-cyanoalkyl sulfones 5a-i, sulfonylheteroaromatics 7a-e, alpha-(sulfonylalkyl)heterocycles 9a-f, alpha-sulfonylalkyl sulfones 11a-g, and esters of alpha-sulfonyl acids 14a-c, respectively, in synthetically useful to excellent yields. The results represent the first ...
B?chele Berthold - - 2005
A rapid, sensitive and selective HPLC separation with photodiode array detection was developed for the analysis of the novel pentacyclic triterpenoid acetyl-11-keto-alpha-boswellic acid. Complete baseline separation of acetyl-11-keto-alpha-boswellic acid from the corresponding isomer acetyl-11-keto-beta-boswellic acid was achieved on a fluorinated stationary phase. The standard curve was linear from 0.98 nmol/l ...
Günther S - - 2005
The human malaria parasite Plasmodium falciparum possesses a single mitochondrion and a plastid-like organelle called the apicoplast. Both organelles contain members of the KADH (alpha-keto acid dehydrogenase) complexes--multienzyme complexes that are involved in intermediate metabolism. In the asexual blood stage forms of the parasites, the alpha-ketoglutarate dehydrogenase and branched chain ...
Chen Zhaobin - - 2005
The photophysical properties of N-(alpha-naphthyl)-benzimidazole (alpha-NABI), N-(beta-naphthyl)-benzimidazole (beta-NABI) and N-(alpha-pyridyl)-benzimidazole (alpha-PYBI) were studied and alpha-NYBI exhibit intramolecular charge transfer fluorescence in polar solvents. The fluorescence of benzimidazoles can be quenched by acetic acid and the existence of exciplexes was observed between the benzimidazole derivatives and acetic acid. Particularly, the maximum ...
Roychowdhury Abhijit - - 2005
The unusual amino acid diaminopimelic acid (DAP) was prepared by cross metathesis of appropriately protected vinyl glycine and allyl glycine derivatives. Catalytic hydrogenation of the cross-coupling product resulted in reduction of the double bond and the removal of protecting groups. The resulting compounds were appropriately protected for the polymer-supported and ...
Xu Hong-wu - - 2005
Herein we present a new example of coordination-mediated resolution of racemic acids by a chiral acid. The reaction of copper(II) acetate monohydrate, optically pure O,O'-dibenzoyltartaric acid (DBTA) and racemic alpha-bromo-2-chlorophenylacetic acid (HL1) in acetonitrile solution afforded a binuclear copper(II) complex with D-DBTA dianion, alpha-bromo-2-chlorophenylacetate and acetate as ligands. After decomposition ...
Hodgson David M - - 2005
[reaction; see text] N-Boc syn-7-(2-hydroxyethyl)-4-(alkyl or aryl)sulfonyl-2-azabicyclo[2.2.1]hept-5-enes serve as precursors in syntheses of the neuroexcitants 3-(carboxymethyl)pyrrolidine-2,4-dicarboxylic acid 43, alpha-kainic acid 12, alpha-isokainic acid 14, and alpha-dihydroallokainic acid 77. The key step in these syntheses is the intermolecular radical addition of 2-iodoethanol to a N-Boc 2-(alkyl or aryl)sulfonyl-7-azabicyclo[2.2.1]heptadiene 7 to induce ...
Chruma Jason J - - 2005
The first functional catalytic mimic of the enzyme dialkylglycine decarboxylase is described. This system utilizes a hydrophobically modified polyethylenimine polymer, a pyridoxamine cofactor, and a 2-aryl-2-alkylglycine sacrificial amine source to convert alpha-keto acids to alpha-amino acids at biologically relevant temperatures with multiple turnovers of the pyridoxamine catalyst. The effects of ...
Fast Jonas - - 2005
HAMLET (human alpha-lactalbumin made lethal to tumor cells) is a complex between alpha-lactalbumin and oleic acid that induces apoptosis in tumor cells, but not in healthy cells. Heteronuclear nuclear magnetic resonance (NMR) spectroscopy was used to determine the structure of 13C-oleic acid in HAMLET, and to study the 15N-labeled protein. ...
Pearson Andrew G - - 2005
This work describes our preliminary efforts towards the development of aryl glucuronides as potential probes for heparanase. During the course of these initial investigations, attempted glycosidation of methyl 2,3,4-tri-O-acetyl-alpha-D-glucopyranosyluronate trichloroacetimidate with 4-hydroxycinnamic acid gave a complex mixture of four different components. These were identified as the 1-cinnamyl glucuronate ester 13, ...
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