Search Results
Results 451 - 500 of 756
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Mulzer Johann - - 1996
The unnatural enantiomer of the amino acid detoxinine and both diastereomeric 3-hydroxy-D-prolines have been prepared from D-mannitol via the O-silylated hydroxyproline 12 as a common key intermediate.
Farrer R G - - 1995
Brefeldin A (BFA) has been used extensively to study the intracellular transport and processing of proteins and sphingolipids because of its dramatic alteration of the structural and functional organization of the Golgi. We have examined the effect of BFA on the synthesis of galactosylceramide sulfate (SGalCer) and its immediate precursor ...
Priebe H - - 1995
The origin of 4-acetyl-2-[N-acetyl-3,5-bis(2,3-dihydroxypropylcarbamoyl)- 2,4,6-triiodoanilinomethyl]-5,7-diiodo-3,4-dihydro-2H-benzo[1,4]ox azine- 6,8-dicarboxylic acid bis(2,3-dihydroxypropylamide) = N-acetyl cyclized iodixanol, 2-[N-acetyl-3,5-bis-(2,3-dihydroxypropylcarbamoyl)-2,4,6- triiodoanilinomethyl]-5,7-diiodo-3,4-dihydro-2H-benzo[1,4]oxazine- 6,8-dicarboxylic acid bis(2,3-dihydroxypropylamide) = cyclized iodixanol and 5,5'-(N-acetyl-2-hydroxypropane-1,3-diyldiamino)bis[N,N'-bis(2,3- dihydroxypropyl)-2,4,6-triiodoisophthalamide] = deacetyl iodixanol in the manufacturing process of the X-ray contrast agent 3,3',5,5'-tetrakis(2,3-dihydroxypropylcarbamoyl)-2,2',4,4',6,6'-++ +hexaiodo- N,N'-(2-hydroxypropane-1,3-diyl)diacetanilide = iodixanol is discussed and their synthesis and purification are described. ...
Wilkins R J - - 1995
The effects of extracellular and intracellular pH on matrix synthesis by isolated bovine chondrocytes were studied using radioisotope incorporation (35SO4 and 3H proline) and fluorescence techniques. Matrix synthesis exhibited a bimodal relation with decreased extracellular pH; with slight reductions (7.4 > pH > 7.1), synthesis increased (by up to 50%), ...
Doares S. H. - - 1995
Salicylic acid (SA) and acetylsalicylic acid (ASA), previously shown to inhibit proteinase inhibitor synthesis induced by wounding, oligouronides (H.M. Doherty, R.R. Selvendran, D.J. Bowles [1988] Physiol Mol Plant Pathol 33: 377-384), and linolenic acid (H. Pena-Cortes, T. Albrecht, S. Prat, E.W. Weiler, L. Willmitzer [1993] Planta 191: 123-128), are shown ...
Morowitz H - - 1995
This paper reports on the non-enzymatic aqueous phase synthesis of amino acids from keto acids, ammonia and reducing agents. The facile synthesis of key metabolic intermediates, particularly in the glycolytic pathway, the citric acid cycle, and the first step of amino acid synthesis, lead to new ways of looking at ...
Rodionov D G - - 1995
The penicillin tolerance exhibited by amino acid-deprived Escherichia coli has been previously proposed to be a consequence of the stringent response. Evidence indicating that penicillin tolerance is directly attributable to guanosine 3',5'-bispyrophosphate (ppGpp) overproduction and not to some other effect of amino acid deprivation is now presented. Accumulation of ppGpp ...
Sugawara T - - 1995
An automated synthesis system, which is suitable for repetitive syntheses using similar reaction procedures, was used to synthesize systematically a library of all possible dipeptides (25) and tripeptides (125) from 5 protected amino acids. The apparatus has also been applied to the automated synthesis of 10 fragment tripeptide derivatives that ...
Moran J K - - 1995
Monoclonal antibodies labeled with radiometals such as copper-67 have applications in radioimmunodiagnosis and radioimmunotherapy. Moi et al. [(1985) Anal. Biochem. 148, 249-253] showed that 6-[p-(bromoacetamido)benzyl]-1,4,8,11-tetraazacyclotetradecane- N,N',N",N"-tetraacetic acid (BAT) is an effective reagent for linking copper to proteins, and antibodies labeled with copper radionuclides are currently undergoing clinical trials. Here we ...
Cho H - - 1995
Escherichia coli thioesterase I (TesA) encoded by the tesA gene is located in the cellular periplasm. The tesA gene was modified by deletion of the leader sequence such that the mature enzyme was instead localized to the cellular cytosol. Production of thioesterase I in the cytosol results in striking changes ...
Quémard A - - 1995
In Mycobacterium tuberculosis isoniazid (INH)-susceptibility and the presence of a thermolabile catalase-peroxidase (T-catalase) are nearly always associated. It is shown in this study that an INH-susceptible strain of M. aurum had a T-catalase activity while its resistant mutants did not, but an in vitro susceptible strain of M. avium had ...
Chen H G - - 1995
Two stereoselective syntheses of a new pseudodipeptide isostere, the right-hand hydroxyethylene dipeptidomimetic (Xaa psi[CH2CH(OH)]Yaa), are presented. In one method readily available amino acids are used as starting materials for Evans chiral aldol condensation chemistry. The second method relies on the synthesis of an anti-aldol product for the hydroxyethylene isostere via ...
Erb E - - 1994
A recursive strategy that solves for the active members of a chemical library is presented. A pentapeptide library with an alphabet of Gly, Leu, Phe, and Tyr (1024 members) was constructed on a solid support by the method of split synthesis. One member of this library (NH2-Tyr-Gly-Gly-Phe-Leu) is a native ...
Cappello A R - - 1994
The short-term effect of T3 and insulin on glycerolipid synthesis from [1-14C] acetate was studied in hepatocytes from both euthyroid and hypothyroid rats. In these conditions fatty acid and cholesterol synthesis were also investigated. Within 4 h after T3 addition to euthyroid cells, a small but significative stimulation of the ...
Granger N A - - 1994
Injection of dibutyryl-cAMP prevents cuticular melanization of black Manduca sexta larvae, whose pigmentation is related to a defect in the control of the corpus allatum. The cAMP analog has no effect in allatectomized black larvae. Significant stimulation of corpus allatum activity was obtained in vitro with compounds which elicit or ...
Fessner W D - - 1994
An efficient technique is presented which integrates cofactor dependent enzymic phosphorylation and dehydrogenation into a single, closed-loop system by employing phosphoenolpyruvate as the sacrificial reagent for sequential ATP and NAD+ recycling steps. Exemplary applications are developed for the synthesis of 6-phosphogluconate from glucose, and that of dihydroxyacetone phosphate from glycerol. ...
Vaidyanathan G - - 1994
Our previously reported method for the 18F labeling of antibodies using N-succinimidyl 4-[18F]fluorobenzoate (SFB) involved a rather long synthesis time. Here we present an improved method for the synthesis of SFB which reduces the synthesis time by about 45 min. A reaction time of 5-8 min (versus 25 min for ...
Chen W - - 1994
hemA and hemM, which are 213 bp apart and divergently transcribed, were separately cloned. We found that hemA is required for 5-aminolevulinic acid (ALA) synthesis in two ALA- auxotrophs. Overexpression of hemM alone did not produce ALA. More ALA was produced by strains harboring a plasmid with both hemA and ...
Watanabe Y - - 1994
Several neuroactive guanidino compounds have been reported to be synthesized in mammals by transamidination reactions. The enzyme(s) responsible for their synthesis and their location in the body has not been well established. The purpose of this investigation was to determine if purified homogeneous rat kidney alpha- and beta-L-arginine : glycine ...
Rane S S - - 1993
A facile synthesis of dl-6,10,14-trimethylpentadecan-2-ol (1) a pheromone component of rice moth, Corcyra cephalonica Stainton and 5,9,13-trimethyltetradecanoic acid (2) a component of marine sponge, Cinachyrella alloclada Uliczka, using a common, intermediate, hexahydrofarnesol is accomplished. The salient features for 1 are: Grignard coupling of 5 with allylmagnesium bromide and oxymercuration-demercuration whereas ...
Osgood D P - - 1993
Arginine was the only amino acid used by Clostridium difficile that permitted cytotoxin synthesis in a peptone-based medium. Synthesis of cytotoxin was delayed when glucose was used as the substrate. Addition of rifampin or puromycin to cultures prior to release of cytotoxin inhibited the release of cytotoxin, suggesting that a ...
Amirmozafari N - - 1993
A defined medium that supported the growth of and synthesis of heat-stable enterotoxin (YST) by clinical isolates of Yersinia enterocolitica at levels equivalent to those observed in a complex Trypticase soy broth-0.6% yeast extract medium was developed. The defined medium contained four amino acids (L-methionine, L-glutamic acid, glycine, and L-histidine), ...
Lerner N R - - 1993
Deuterium-enriched amino acids occur in the Murchison carbonaceous chondrite. Synthesis from D-enriched interstellar precursors by Strecker reactions during aqueous alteration of the parent body has been proposed. To test this hypothesis, we have measured the retention of deuterium in amino acids produced from HCN, NH3, and formaldehyde-D2, acetaldehyde-D4, and acetone-D6 ...
Thaden J - - 1993
To provide a solid support for automated synthesis of 3'-(aminoalkyl)-modified oligonucleoside methylphosphonates, controlled pore glass beads were functionalized with a protected N-(3-aminoprop-1-yl)-N-(2-hydroxyethyl)-2-aminoethyl ester of succinic acid. This "Aha-CPG" was used for automated synthesis of oligo-2'-deoxyribonucleoside methylphosphonates having either of two distinct 3' terminal modifications. If the first coupling to the ...
Magnuson K - - 1993
Our understanding of fatty acid biosynthesis in Escherichia coli has increased greatly in recent years. Since the discovery that the intermediates of fatty acid biosynthesis are bound to the heat-stable protein cofactor termed acyl carrier protein, the fatty acid synthesis pathway of E. coli has been studied in some detail. ...
Fan G - - 1993
The effects of okadaic acid on ornithine decarboxylase (ODC) activity and milk product formation were studied in cultured mammary tissues derived from midpregnant mice. Okadaic acid stimulated ODC activity as well as the synthesis of lactose, lipids, and casein-rich phosphoproteins. When tested together, okadaic acid and prolactin evoked a nonadditive ...
Pugh K C - - 1993
3-Nitro-2-pyridinesulfenyl chloride (NpysCl) is the starting material for the synthesis of N-, O- and S-Npys-protected amino acids. Two efficient, novel synthetic routes to NpysCl are described. The stability of NpysCl was determined in a variety of solvents, with and without base, to determine the most suitable solvent and base for ...
Herranz R - - 1993
The synthesis of (6R,5S,2RS)-6-amino-5-hydroxy-2-isobutyl-4-oxo-7- phenylheptanoic acid (9), a carbaanalogue of the aminopeptidase (AP) inhibitor bestatin (1) is described. This synthesis was carried out by a malonic ester alkylation with the suitably protected halomethyl ketone of (2S,3R)-AHPBA*), followed by a second alkylation with isobutyl bromide of the resulting 4-ketodiester, and subsequent ...
Elliott M E - - 1993
Previous work from this laboratory has suggested that the adrenal glomerulosa is under tonic inhibition by fatty acids. The purpose of the present work was to define the mechanism by which fatty acids inhibit aldosterone synthesis. Experiments with isolated bovine adrenocortical cells showed the following. 1) Fatty acids inhibited angiotensin-II-stimulated ...
Safavy A - - 1993
In an effort to generate bifunctional chelating agents (BCAs) with improved labeling, conjugation, and biodistribution properties, the synthesis of trisuccin is reported. This new hydroxamate BCA, after synthesis and characterization, was used for conjugation and radiolabeling of monoclonal antibodies with 99mTc. This new class of synthetic BCAs may be useful ...
Iyer R S - - 1993
Aflatoxin B1 is a potent carcinogen which requires activation in order to react with DNA. The exo-8,9-epoxide is putatively the active form although it has thus far eluded direct detection in biological systems. This laboratory has reported a synthesis of the epoxide using dimethyldioxirane as the oxidant [(1988) J. Am. ...
Lortie R - - 1993
The kinetics of the synthesis of triolein catalyzed by immobilized Mucor miehei lipase were studied. Equilibrium constants for the synthesis of mono-, di-, and triolein were calculated from the equilibrium compositions for different initial ratios of glycerol and oleic acid by means of multiresponse regression. The 1,3-specific lipase can catalyze ...
Roughan G. - - 1993
Long-chain fatty acid synthesis from [1-14C]acetylcarnitine by chloroplasts isolated from spinach (Spinacia oleracea), pea (Pisum sativum), amaranthus (Amaranthus lividus), or maize (Zea mays) occurred at less than 2% of the rate of fatty acid synthesis from [1-14C]acetate irrespective of the maturity of the leaves or whether the plastids were purified ...
Arzeno H B - - 1993
Methodology for the large-scale, solid-phase synthesis of nafarelin, I, an LH-RH agonist and RS-26306, III, and LH-RH antagonist, is described. N alpha-Boc protected amino acids were used in the synthesis. The only side-chain-protected amino acids required were BocHis(Tos)-OH and BocSer(t-Bu)-OH. The use of temporary protection on serine eliminates the formation ...
Lehnert H - - 1993
Brain catecholamine and serotonin neurons are intimately involved in a number of physiological functions such as cardiovascular regulation, neuroendocrine secretion, regulation of behavior, mood and appetite control. The synthesis and release of these neurotransmitters appear to be remarkably correlated with the subsequent physiological changes observed. While there are numerous pharmacological ...
Shin H C - - 1993
A rapid and high-yielding two-step synthesis of fatty thioacids from readily available starting materials has been devised. In the first step, an acid chloride is reacted with thioacetic acid at room temperature to produce a mixed thioanhydride, which in the second step is nucleophilically deacetylated with propylamine or butylamine at ...
Peak M - - 1992
We investigated the interactions of insulin and okadaic acid, an inhibitor of protein phosphatases type-2A and type-1, on glycogen synthesis in rat, guinea pig and rabbit hepatocytes. Insulin stimulated glycogen synthesis in rat and guinea pig but not in rabbit hepatocytes. In rat and guinea pig hepatocytes, the stimulation of ...
Takeda M - - 1992
Guanidinoacetic acid, a precursor of creatine, is an essential substrate for muscle energy metabolism. Since guanidinoacetic acid has been reported to be synthesized from arginine and glycine by glycine amidinotransferase (transamidinase) in kidney homogenates or slices, the purpose of this study was to provide evidence of guanidinoacetic acid synthesis in ...
Quémard A - - 1992
Striking structural analogies exist between the two specific antimycobacterial drugs ethionamide (ETH) and isoniazid (INH), and they share several inhibitory properties in susceptible species of mycobacteria. The effect of ETH on mycolic acid synthesis was studied in whole cells and in cell extracts of various species, since this synthesis is ...
Soler C C Departament de Bioquímica i Fisiologia, Universitat de Barcelona, - - 1992
Ornithine decarboxylase (ODC) activity is induced by protein-synthesis independent mechanisms in freshly isolated rat hepatocytes, incubated either without or with a mixture of amino acids in the incubation medium. Urea synthesis rates were two- to three-fold higher in those hepatocytes incubated in the presence of amino acids that in those ...
Smith R G - - 1992
Leucoplasts were isolated from the endosperm of developing castor (Ricinis communis) endosperm using a discontinuous Percoll gradient. The rate of fatty acid synthesis was highest when malate was the precursor, at 155 nanomoles acetyl-CoA equivalents per milligram protein per hour. Pyruvate and acetate also were precursors of fatty acid synthesis, ...
Sharan R N - - 1992
Aqueous, acetic acid, hydrochloric acid and ethanol extracts of betel nut (Areca catechu L.) have been found to induce unscheduled DNA synthesis in Hep 2 cells obtained from human larynx carcinoma, in vitro. Different concentrations of extracts of betel nut induced dose-dependent unscheduled DNA synthesis in Hep 2 cells. Together ...
Di Giacomo M - - 1992
Following our research on the arachidonic acid metabolites and their derivatives with potential biological activity, we describe the synthesis of the (+-)-8,12-trans-(5Z, 14Z)-9-oxo-prosta-5,14-dienoic acid, a 11-deoxyprostanoid correlated to the class of Preclavulones, one of the unusual families of marine eicosanoids from the coral Clavularia Viridis with considerable biological interest.
Hiltunen M - - 1992
The fatty acid synthase inhibitor cerulenin (50 to 100 micrograms/ml) inhibited production of the polyketide mycotoxins alternariol (AOH) and alternariol monomethyl ether (AME) by the mold Alternaria alternata. The results suggested that AOH synthesis was inhibited by a direct mechanism by cerulenin, whereas production of AME was probably limited by ...
Westby A A Natural Resources Institute, Central Avenue, Chatham Maritime, ME4 4TB, Chatham, Kent, - - 1992
Processes for the production ofgari, East Nigerianfu-fu and West Nigerianfu-fu are described. Changes in pH value, moisture content, microflora and sugar content of cassava duringgari andfu-fu preparation are reported. Mannitol accumulated during thegari fermentation but not in either of thefu-fu fermentations. During each stage ofgari andfu-fu production, lactic acid bacteria ...
Tijburg L B - - 1992
Okadaic acid, a specific inhibitor of protein phosphatase 1 and 2A, inhibited the synthesis of phosphatidylethanolamine via the CDPethanolamine pathway in isolated hepatocytes. Pulse-chase experiments and measurement of the enzyme activity demonstrated that the inhibition of phosphatidylethanolamine synthesis was not caused by an inhibition of CTP:phosphoethanolamine cytidylyltransferase, the putative regulatory ...
Lee W N - - 1992
The synthesis of a homonucleus polymer from its labeled precursor will lead to the formation of molecules with different masses. The distribution of these mass isotopomers is strictly a function of the enrichment of the 13C-labeled precursor, and can thus be used for the determination of the precursor enrichment and ...
Farmer E. E. - - 1992
Jasmonic acid and methyl jasmonate have been shown previously to be powerful inducers of proteinase inhibitors in tomato, tobacco, and alfalfa leaves. We show here that when proposed octadecanoid precursors of jasmonic acid, i.e., linolenic acid, 13(S)-hydroperoxylinolenic acid, and phytodienoic acid, were applied to the surfaces of tomato leaves, these ...
Siedler F - - 1992
The synthesis is described for muramyl-dipeptide-related amphiphilic analogs, where 1,10-diaminodecane served as a lipophilic C-terminal linker for the preparation of a bidentated L-alanyl-D-isoglutamine derivative and incorporation of aldonic and uronic acids at the N-termini as hydrophilic cores. For the N-acylation steps via lactones, suitable conditions were elaborated to allow for ...
Bissonnette R - - 1992
RNA synthesis was examined by radioautography in mouse duodenal epithelium using 3H-uridine as a tracer of the salvage pathway and 3H-orotic acid as a tracer of the de novo pathway. The incorporation of the two precursors was estimated by counting silver grains in light-microscopic and electron-microscopic radioautographs at successive levels ...
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