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Results 351 - 400 of 684
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Lee S - - 1993
The in vitro sensitivity of Plasmodium falciparum to bleomycin, busulfan, camptothecin, CC-1065, cisplatin, daunomycin, distamycin, luzopeptin, mAMSA, mitomycin C, naladixic acid, U71184, VM26, and VP16, or combinations of them was examined. The lethal dose concentration for 50% of parasites for 3 compounds, luzopeptin, CC1065, and U71184, that bind to adenine-thymidine-rich ...
Manjeshwar S - - 1993
The present study was designed to determine the mechanism by which orotic acid, a rat liver tumor promoter, inhibits DNA synthesis in normal hepatocytes in primary culture. Our results indicate that orotic acid inhibited the epidermal growth factor induced expression (mRNA) of both M1 and M2 subunits of ribonucleotide reductase ...
McClarty G - - 1993
Pyrimidine metabolism was studied in the obligate intracellular bacterium Chlamydia psittaci AA Mp in the wild type and a variety of mutant host cell lines with well-defined mutations affecting pyrimidine metabolism. C. psittaci AA Mp cannot synthesize pyrimidines de novo, as assessed by its inability to incorporate aspartic acid into ...
McClarty G - - 1993
Purine metabolism was studied in the obligate intracellular bacterium Chlamydia psittaci AA Mp in the wild type and a variety of mutant host cell lines with well-defined deficiencies in purine metabolism. C. psittaci AA Mp cannot synthesize purines de novo, as assessed by its inability to incorporate exogenous glycine into ...
Tazuya K - - 1993
We studied the origin of the N-1 atom of the pyrimidine moiety of thiamin in a eucaryote, Saccharomyces cerevisiae. The competitive effects of 14N-compounds on the incorporation of 15N-NH4Cl into the pyrimidine moiety were examined. Amino acids, the bases of nucleic acids and glucosamine did not decrease 15N incorporation, but ...
Nordhoff E - - 1993
Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) with infrared laser light of a wavelength of 2.94 microns has been used for the analysis of nucleic acids. Spectra of oligodeoxynucleotides up to 26 nucleotides, oligothymidylic acids up to 100 nucleotides as well as different synthetic RNA oligomers and RNA transcripts up to ...
Ogbunude P O - - 1993
A free living protozoon, Acanthamoeba polyphaga 435/89, was shown to utilize radiolabelled formate and glycine as precursors for purine biosynthesis and to grow in medium devoid of any source of preformed purine compounds. The organism also incorporated into its nucleic acids radiolabel derived from adenosine and guanosine indicating presence of ...
Franco L - - 1993
Incubation of ADPribose with yeast phosphoriboisomerase resulted in the formation of an adenylic nucleotide that was identified with ADPribulose by mass spectrometry. Synthesis of [32P]ADPribulose from [32P]NAD+ by the combined activities of commercial NAD+ glycohydrolase and phosphoriboisomerase allowed us to use it as a labeled internal standard throughout the procedure ...
Baumann U - - 1993
A diversification of the genetic code based on the number of codons available for the proteinous amino acids is established. Three groups of amino acids during evolution of the code are distinguished. On the basis of their chemical complexity those amino acids emerging later in a translation process are derived. ...
Miller-Patrick K - - 1993
De novo synthesis precursors of the purine second messengers adenosine, guanosine and inosine are adenosine, guanosine and inosine monophosphate (AMP, GMP, IMP), respectively. Inhibitors of the de novo purinergic synthesis pathways for AMP, GMP and IMP by hadacidin, mycophenolic acid and azaserine, respectively, or adenosine, guanosine or inosine alone or ...
Yamamoto F - - 1993
We have employed a PCR approach to determine the nucleotide sequences of the coding region in the last two coding exons of the histo-blood group ABO genes from one A(X) and one B(A) individual. Compared with A1 alleles, the (A(X)) allele has a single nucleotide substitution (T-->A at nucleotide 646) ...
Hammerschmid F - - 1992
Reverse transcriptase activity was measured by incorporation of dUMP linked to digoxigenin into a suitable template-primer molecule. Incorporation was monitored by using peroxidase-conjugated Fab fragments directed against digoxigenin. The standard assay measuring incorporation of radiolabeled nucleotides into acid-precipitable material was compared with this new immunochemical assay with regard to its ...
Iwashima A - - 1992
Adenosine, at 1 mM concentrations or above, was found to have a fungistatic effect on Saccharomyces cerevisiae. A substance with amethyst fluorescence was detected in the medium of adenosine-inhibited cultures of S. cerevisiae. This compound was isolated and physicochemically identified as anthranilic acid. Both the inhibition of growth and release ...
Freeman G A - - 1992
3'-Azido-3'-deoxythymidine-5'-phosphonate was synthesized by a five-step reaction sequence. The 5'-phosphonate was inactive against HIV-1 in MT4 cells. The absence of activity against HIV-1 was at least partially explained by demonstrating that the Km value for the 5'-deoxy-5'-methylphosphonic acid diphosphate analog with HIV-1 reverse transcriptase (RT) was 320-fold greater than the ...
Lee P K - - 1992
Toxic shock syndrome toxin (TSST) 1 was purified from ovine (TSST-ovine) and bovine (TSST-bovine) mastitis-associated Staphylococcus aureus. These toxins were previously reported to have molecular weights identical to that of human TSST-1. However, TSST-ovine was reported as having an isoelectric point (pI) of 8.5, whereas TSST-bovine has the same pI ...
Alvarez R - - 1992
A method for the separation of cyclic AMP from adenosine and polyvalent adenine nucleotides is described. The method consists of the sequential elution of adenosine and cyclic AMP from a single column of acidic aluminum oxide (alumina) with dilute hydrochloric acid and ammonium acetate. Adenosine, adenine, xanthine, and hypoxanthine are ...
Vapalahti O - - 1992
The prototype Puumala virus (PV) Sotkamo strain small (S) and medium (M) RNA genome segments were amplified by the polymerase chain reaction (PCR), cloned and sequenced. The S segment is 1830 nucleotides long with an open reading frame coding for 433 amino acids. The identity to the PV Hällnäs strain ...
Gozar M M - - 1992
A variety of anti-mitochondrial drugs that had previously been found to inhibit the growth of the malarial parasite Plasmodium falciparum were tested on Babesia bovis in vitro. Several of these drugs were found to be non-toxic towards B. bovis. However, those drugs that were found to inhibit babesial growth included ...
Visek W J - - 1992
Orotic acid, first discovered in ruminant milk, is an intermediate in the pyrimidine biosynthesis pathway of animal cells. Its synthesis is initiated by the formation of carbamoyl phosphate (CP) in the cytoplasm, with ammonia derived from glutamine. Ureotelic species also form CP in the first step of urea synthesis in ...
Manjeshwar S - - 1992
This study was designed to determine the possible mechanism by which orotic acid exerts its mitoinhibitory effect on rat hepatocytes in primary culture. Orotic acid inhibited, dose-dependently DNA synthesis in hepatocytes induced by epidermal growth factor, transforming growth factor alpha, hepatocyte growth factor, acidic fibroblast growth factor, or plasma from ...
Miyakoshi S - - 1992
Biosynthesis of griseolic acids, competitive inhibitors of cyclic nucleotide phosphodiesterase, was investigated with the culture of a producing strain of Streptomyces griseoaurantiacus. 13C-Labeled and 15N-labeled compounds were added into the culture, and 13C-enriched and 15N-enriched griseolic acid A was isolated from the culture medium and analyzed by 13C NMR and ...
Arkin A P - - 1992
In random mutagenesis, synthesis of an NNN triplet (i.e. equiprobable A, C, G, and T at each of the three positions in the codon) could be considered an optimal nucleotide mixture because all 20 amino acids are encoded. NN(G,C) might be considered a slightly more intelligent "dope" because the entire ...
Kinjo J E - - 1992
The oligonucleotide ppp5'A2'p5'A2'p5'A, known as 2-5A, is a potent translational inhibitor involved in some aspects of interferon action. To explore the specific function of the charged 5'-triphosphate moiety, we prepared a series of congeners in which the 5' region was hypermodified. Thus, uronic acid derivatives were substituted for the 5' ...
Zoref-Shani E - - 1992
The metabolic fate of labeled hypoxanthine and inosine, degradation products of adenine nucleotides, was studied in cultured beating cardiomyocytes, in order to assess the physiological significance of their contribution to salvage nucleotide synthesis in the heart. Inosine and hypoxanthine were found to be incorporated into nucleotides by a similar rate, ...
Alexiou M - - 1992
The importance of de novo purine synthesis as opposed to the reutilisation of metabolites by salvage pathways, and the nature of the excretory product(s) of purine degradation, have been examined in cultured preimplantation mouse embryos. In the presence of azaserine and mycophenolic acid, which inhibit de novo purine synthesis, embryo ...
Wickramasinghe N S - - 1992
We recently reported that esterification of 5'-AMP with N-acetyl amino acids proceeds with a preference for D-amino acids, and the D/L ratio in products declines as the hydrophobicity of the amino acid declines. Using one amino acid, Ac-Val, we now show that esterification of all four nucleotides proceeds with a ...
Sollinger H W - - 1992
RS-61443, the morpholinoethyl ester of mycophenolic acid (mPA), is a potent, noncompetitive, reversible inhibitor of eucaryotic inosine monophosphate (IMP) dehydrogenases. Because of the importance of the guanosine and deoxyguanosine nucleotides in activating phosphoribosyl pyrophosphate (PRPP) synthesis and ribonucleotide reductase, respectively, it was postulated that depletion of GMP (and consequently GTP ...
Ewing D F - - 1991
(2-Deoxy-D-erythro-pentofuranosyl)imidazole nucleosides have been synthesised by glycosylation of the sodium salt of ethyl 5-aminoimidazole-4-carboxylate with 2-deoxy-3,5-di-O-p-toluoyl-alpha-D-erythro-pentofuranosyl chloride. Glycosylation of ethyl 5-aminoimidazole-4-carboxylate with 2-deoxy-beta-D-erythro-pentofuranose was also achieved enzymically using E. coli, immobilised by ionotropic gelation in an alginate gel, with 2'-deoxyuridine as glycosyl donor. 5-Amino-1-(2-deoxy-beta-D-erythro-pentofuranosyl)imidazole-4-carboxylic acid 5'-phosphate and 4-amino-1-(2-deoxy-beta-D-erythro-pentofuranosyl)imidazole-5-carboxylic acid 5'-phosphate ...
McKee T - - 1991
Several investigations have indicated that Tetrahymena pyriformis secretes ribonuclease activity into culture media. The extracellular ribonuclease from strain W has been purified and partially characterized. The molecular weight was determined by gel filtration to be 26,500. The amino acid composition of the enzyme was compared with those of the three ...
Chikenji T - - 1991
The effects of abdominal surgery on protein, RNA, and de novo purine nucleotide synthesis in lymphocytes, and modification of these changes by postoperative amino acid supply, were investigated in 24 patients undergoing cholecystectomy (n = 12) or removal of gastric cancer (n = 12). Mono-nuclear cells were isolated from the ...
Eisenreich W - - 1991
The biosynthesis of deazaflavins, flavins, ribonucleotides, and selected amino acids was studied in Methanobacterium thermoautotrophicum by incorporation of 13C-labeled acetate and pyruvate. 13C enrichments were monitored by 13C and 1H NMR spectroscopy. The biosynthesis of ribonucleotides follows the standard pathway. The xylene ring of riboflavin is formed from two pentose ...
Jeevanandam M - - 1991
Hypermetabolic responses with respect to pyrimidine and purine kinetics in trauma victims were investigated during the catabolic phase before and after nutritional support. Orotic acid and uric acid excretions were measured in 32 adult, severely traumatized, hypermetabolic, and highly catabolic patients while they were receiving fluids with no calories or ...
Wickramasinghe N S - - 1991
Biological systems synthesize proteins with an almost exclusive use of L-amino acids and virtually none of the D isomer. There has been no satisfactory explanation for the origin of this use of the L isomer. Research presented here shows that at pH 5, transfer of phenylalanine from the adenylate anhydride ...
Berners-Price S J - - 1991
The effect of the antitumor complex [Au(dppe)2]Cl (where dppe is Ph2P(CH2)2PPh2) on the overall metabolism of cultured mouse L1210 leukemia cells was investigated by comparing 1H and 31P NMR spectra of perchloric acid extracts of cells incubated for 1 h in the presence and absence of 2 microM [Au(dppe)2]Cl. There ...
Schönfeld P - - 1991
In incubations with isolated rat liver mitochondria we studied the fuel properties of octanoate as medium-chain fatty acid and respiratory substrate and the extent of control exerted by adenine nucleotide translocase on mitochondrial respiration. While, compared with pyruvate, octanoate improved the hydrogen supply in the active state to be seen ...
Kay H H - - 1991
Phosphorus 31 magnetic resonance spectroscopic studies of fresh placental tissue are reported that indicate resonances for adenosine triphosphate, inorganic phosphate, sugar phosphates-phosphomonoesters, and phosphodiesters. Perchloric acid extract methods were used to further characterize and quantitate phosphorous metabolites in term human placentas by phosphorus 31 magnetic resonance spectroscopy. The perchloric acid ...
Le Hir M - - 1991
An impurity, probably an anion, present in some batches of the buffer substances 4-(2-hydroxyethyl) piperazine-1-ethanesulfonic acid (HEPES), 2-morpholinoethane sulfonic acid (Mes) and piperazine-1,4-bis(2-ethane sulfonic acid (Pipes), activates the soluble 5'-nucleotidase from rat kidney. The affinity of the enzyme for 5'-IMP and the Vmax were both increased by the unidentified activator. ...
Lyons S D - - 1990
Exposure of mouse L1210 leukemia cells to 25 microM brequinar for 4 h results in large accumulations of N-carbamyl-L-aspartate and L-dihydroorotate to cellular concentrations of 8.5 mM and 0.8 mM, respectively, while UTP and CTP decrease to 4% of their initial levels; incorporation of [14C]bicarbonate into nucleic acids (DNA and ...
Sze D Y - - 1990
Nuclear magnetic resonance (NMR) studies of extracts have proven to be a powerful window onto the intracellular machinery of cells and tissues. The major advantages of in vitro 1H-NMR, namely chemical preservation, simultaneous detection, identification, and quantitation of compounds, and sensitivity to a large variety of classes of compounds, are ...
Fitch W M - - 1990
In a study of mammalian ribonuclease evolutionary rates, we applied the Fitch-Bruschi correction to reduce the bias caused by an unequal sampling of taxa in different lineages. The correction was clearly appropriate but only up to a point. The analysis showed that the sampling of taxa within the pecora was ...
Watkins J B JB - - 1990
Large, rapid decreases in hepatic UDP-glucuronic acid concentrations occur in rats following exposure to myriad chemicals. In fact, 80% reductions in UDP-glucuronic acid occur within minutes after exposure to inhalation anesthetics. The present study was designed to determine whether this decrease in hepatic UDP-glucuronic acid may be due to (a) ...
Yamashita T - - 1990
Quantitative changes in carbohydrates, amino acids and adenine nucleotides in the stems of mulberry trees (Morus alba L., cv. Shin-ichinose) were followed from spring to early summer and from autumn to early spring. Both ATP and ADP content of stems increased before bud break, whereas the content of sucrose, the ...
Harvey B H - - 1990
Evidence is presented for a novel proposal for the mechanism of action of lithium in manic depressive psychosis. Lithium has well established effects on catecholaminergic--and hormone--stimulated adenyl cyclase activity and on cyclic AMP formation. Although there is conflicting evidence in the literature concerning the effects of the ion on cyclic ...
Görner H - - 1990
The emission spectra of nucleic acids, pyrimidine and purine nucleotides, nucleosides and bases and a series of pyrimidine derivatives were obtained using UV light excitation in glasses (ethanol and 2:1 mixtures of ethylene glycol and water (EG-H2O); also partly in butyronitrile and 2-methyltetrahydrofuran) at 77 K. The quantum yields of ...
Zaharevitz D W - - 1990
The amount of newly synthesized uracil nucleotides in mouse liver and intestine was determined by analysis of 15N incorporation into the uracil nucleotide pool of these tissues after intraperitoneal infusion of 15N-labelled amino acids. The appearance of newly synthesized uracil nucleotides was linear with time, and essentially independent of the ...
Watkins J B JB - - 1990
Because hepatic UDP-glucuronic acid levels decrease upon exposure to volatile anesthetics, the present study was designed to determine the mechanism by which enflurane decreases UDP-glucuronic acid in mice by measuring the concentrations of intermediates and the activities of enzymes in the UDP-glucuronic acid pathway. UDP-glucuronic acid concentrations were decreased by ...
Hedstrom L - - 1990
Inosine 5'-monophosphate dehydrogenase (IMPDH) catalyzes the oxidation of inosine 5'-monophosphate (IMP) to xanthosine 5'-monophosphate (XMP) with the conversion of NAD to NADH. An ordered sequential mechanism where IMP is the first substrate bound and XMP is the last product released was proposed for Tritrichomonas foetus IMPDH on the basis of ...
Karlsson A - - 1990
When CEM cells were incubated with [3H]-labeled 3'-azido-2',3'-dideoxyguanosine (AzddGuo), the isotope was largely recovered as ribo- and deoxyribonucleotides in the acid soluble fraction of CEM cells, due to extensive catabolism of AzddGuo and recycling of the guanine formed by purine nucleoside phosphorylase. Only 10% was found as the AzddGuo nucleotides, ...
Kopff M - - 1990
The activity of inosine triphosphate pyrophosphohydrolase (ITPH) in human erythrocytes was found to be 1.50 +/- 0.39 mumol of inosine triphosphate (ITP) hydrolysed x min-1 per g Hb, and no measurable amount of ITP was detected. When dipyridamole was added to the medium composed of adenosine, pyruvate and inorganic phosphate, ...
Staak S - - 1990
The present study was carried out to investigate the time course of metabolization in brain and the influence on RNA synthesis of a retention-improving dosage of methylglucamine orotate after intracerebroventricular application. As determined by the HPLC technique, 73% of acid-soluble radioactivity were recovered in unmetabolized orotic acid 30 min after ...
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