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1.
The formation of phosphoribosylpyrophosphate (PRPP) and adenosine 5′-monophosphate (AMP) from ribose 5-phosphate and adenosine 5′-triphosphate, catalyzed by purified PRPP synthetase from Salmonella typhimurium, was conducted in 18O-enriched water. The products were isolated, and inorganic phosphate was isolated from AMP and the pyrophosphoryl moiety of PRPP. Oxygen-18 was incorporated into PRPP but not into AMP. These results indicate that PRPP synthesis proceeds with scission of a βPO bond of adenosine 5′-triphosphate. Oxygen-18 enters PRPP by prior exchange of H218O into ribose 5-phosphate; the rate of this exchange was measured by combined gas chromatography-mass spectrometry of the trimethylsilyl derivative of ribose 5-phosphate. 相似文献
2.
A series of 2′-fluorinated adenosine compounds, dAfl, dAflp, pdAfl, dAfl-A, A-dAfl, and dAfl-dAfl, have been investigated by nmr spectroscopies. The 1H-, 19F-, and 31P-nmr data provide structural information from different parts of these moleucles. The pKa of the phosphate group of these two 2′-fluoro-2′-deoxyadenosine monophosphates was found to be the same as that of hte parent adenosine monophosphate. As for the pentose conformation, the 3E population is greatly increased as a result of the fluorine substitution at the C2′ position. However, the populations of conformers of gg (C4′-C5′) and g′g′ (C5′-O5′) and the average angle ?′(C3′-O3′) of the 2′-fluoro compounds remain unchanged as compared to the natural riboadenosine monomer and dimer (A-A). Thefefore, the backbone conformation of the 2′-fluoro-2′-deoxy-adenosine, its monophosphates and dimers, resembles that of RNA. The extent of base-base overlapping in these 2′-fluoro-2′-deoxy-adenosine-containing dimers is also found to be similar to or even greater than A-A. Thus, the conformations of these compounds can be considered as those in the RNA family. These fluorocompounds also serve as models for a careful study on the 19F-nmr in nucleic acid. The 19F chemical-shift values are sensitive to the environment of the fluorine atom such as ionic structure of the neighboring group(s) (phosphate of base), solvation, and ring-ruccent anisotropic effect from the base(s). Qualitatively, the change of the 19F chemical-shift values (up to 2 ppm) is much larger than that of 1H-nmr (up to 0.5 ppm) in the dimers. Using dAfl·poly(U), poly(dAfl)·poly(dAfl), and poly(dAfl)·poly(U) helix–coil transition as model systems, the linewidth of 19F in dAfl- residues reflects effectively the mobility of the unit in the nucleic acid complex as calibrated by uv data and by 1H-nmr. Therefore, application of 19F-nmr spectroscopy on fluorine-substituted nucleic acid can also be used to detect nucleic acid-nucleic acid interaction in complicated systems. 相似文献
3.
Primary structure of E. coli alanine transfer RNA: relation to the yeast phenylalanyl tRNA synthetase recognition site 总被引:11,自引:0,他引:11
R J Williams W Nagel B Roe B Dudock 《Biochemical and biophysical research communications》1974,60(4):1215-1221
Nucleotide sequence comparison of tRNAs aminoacylated by yeast phenylalanyl tRNA synthetase (PRS) have lead to the proposal that the specific nucleotides of the dihydrouridine (diHU) stem region and adenosine at the fourth position from the 3′ end are involved in the PRS recognition site. Kinetic analysis and enzymatic methylation have shown that the size of the diHU loop and the methylation of guanine at position 10 from the 5′ end both directly affect the PRS aminoacylation kinetics. tRNA1A1a, which is aminoacylated by PRS, should therefore have 1- the specific nucleotides of the diHU stem region and, 2- adenosine at position 4 from the 3′ end. The PRS aminoacylation kinetics of this tRNA indicates that this molecule 3- has a diHU loop of 8 nucleotides and 4- has an unmethylated guanine at position 10 from the 5′ end. We report here the complete sequence of tRNA1A1a and confirmation of each of these four predictions. 相似文献
4.
《Plant Science Letters》1978,11(3-4):177-183
Adenosine 5′-phosphosulfate-sulfotransferase is the first enzyme in the pathway of assimilatory sulfate reduction in Chlorella, and transfers the sulfo group from APS (adenosine 5′-phosphosulfate) to a thiol acceptor forming an organic thiosulfate. In vitro, adenosine 5′-phosphosulfate-sulfotransferase transfers to a variety of thiol acceptors, the best among the monothiols is glutathione, the only one to show a regulatory interaction with adenosine 5′-phosphosulfate-sulfotransferase. To identify the physiological acceptor, adenosine 5′-phosphosulfate-sulfotransferase is assayed without thiols; the cell fraction which stimulates adenosine 5′-phosphosulfate-sulfotransferase activity is expected to contain the physiological acceptor. Boiled Chlorella extract contains physiological acceptor when assayed in the presence of adenosine 5′-phosphosulfate-sulfotransferase and NADPH. Physiological acceptor is dialyzable but is retained by filters of 1000 daltons cut off. After passage through DEAE—Sephadex A-25 and Sephadex G-25, physiological acceptor is found to be ninhydrin-positive and shows co-electrophoresis with oxidized glutathione. Upon reduction with dithiothreitol, physiological acceptor moves with reduced glutathione and on acid hydrolysis yields amino acids identical with those from authentic oxidized glutathione. Physiological acceptor, with adenosine 5′-phosphosulfate-sulfotransferase and AP35 S, yields labeled glutathione—S—SO3−. Thiosulfonate reductase from Chlorella reduces glutathione—S—SO3− to bound sulfide. Only one active accepting component is found in the boiled extracts. 相似文献
5.
Michael E. Perlman 《Nucleosides, nucleotides & nucleic acids》2013,32(1):73-82
Abstract The 2′-deuterio arabino analogs of tubercidin and adenosine have been prepared by Swern oxidation of the 3′,5′-TPDS derivatives of tubercidin and adenosine and reduction with NaBD4. Subsequent inversion of stereochemistry at C-2′ yielded [2′-2H]tubercidin and [2′-2H]adenosine with 98% deuterium incorporation. 相似文献
6.
J. Yano L.S. Kan P.O.P. Tso 《Biochimica et Biophysica Acta (BBA)/General Subjects》1980,629(1):178-183
A simple and effective method of the methylation on the 2′-O position of adenosine is described. Adenosine is treated with CH3I in an anhydrous alkaline medium at 0°C for 4 h. The major products of this reaction are monomethylated adenosine at either the 2′-O or 3′-O position (total of 64%) and the side products are dimethylated adenosine (2′,3′-O-dimethyladenosi, 21%, and N6-2′-O-dimethyladenosine, 11%). The ratio of 2′-O- and 3′-O-methyladenosine has been found to be 8 to 1. Therefore, this reaction preferentially favors the synthesis of 2′-O-methyladenosine. The monomethylated adenosine is isolated from reaction mixture by a silica gel column chromatography. Then the pure 2′-O-methyladenosine can be separated by crystallization in ethanol from the mixture of 2′-O and 3′-O-methylated isomers. The overall yield of 2′-O-methyladenosine is 42%. 相似文献
7.
Antagonistic effect of methadone on steroidogenesis and the adenylate cyclase system in isolated rat adrenocortical cells 总被引:1,自引:0,他引:1
Methadone exhibits an antagonistic effect toward steroidogenesis which lies prior to progesterone in the biosynthetic pathway in isolated rat adrenal cells. Levels of adenosine cyclic 3′–5′ monophosphate are depressed in a dose dependent fashion in ACTH stimulated cells as is steroidogenesis in cells stimulated with N6O2-dibutyryl adenosine cyclic 3′–5′ monophosphate. Stimulation produced by the ACTH analog, O-nitrophenyl sulfenyl ACTH, is also inhibited by methadone. The participation of adenosine cyclic 3′–5′ monophosphate as an obligatory messenger in ACTH stimulated steroidogenesis is discussed with respect to the pharmacological properties of methadone in this system. 相似文献
8.
(1) Synaptosomal fractions from guinea pig neocortical dispersions prepared in sucrose solutions were deposited from saline media as ‘beds’ on nylon bolting cloth. When incubated with 0.5–10 μm -[14C]adenine or adenosine in glucose bicarbonate salines, uptake of 14C from adenosine proceeded at about four times the rate of uptake of [14C]adenine. This contrasted with the relative uptake of the two compounds to neocortical tissue slices or to beds made from mitochondrial fractions, where uptake was similar with the two precursors. Uptake of both precursors to synaptosome beds was much greater than uptake of inosine. (2) Synaptosome beds, [14C]adenosine-loaded, contained 88 per cent of the 14C as 5′-adenine nucleotides, the remainder being present as cyclic AMP, inosine, hypoxanthine and adenosine. When superfused, the 14C output consisted mainly of adenosine, inosine and hypoxanthine, with some 7 per cent of 5′-nucleotides and 4 per cent of cyclic AMP. (3) Electrical pulses and the addition of 50 mm -KCl each increased the efflux of 14C from superfused [14C]adenosine-loaded beds. The superfusates issuing after excitation contained the same 14C-labelled compounds as issued before, with a small increase in the proportional yield of adenosine. The additional output of 14C following electrical pulses was diminished by about 50 per cent by 0.5 μm -tetrodotoxin while that following KCl was not affected; it was however prevented when the superfusing fluids were free of Ca2+. 相似文献
9.
Trichothecene Biosynthesis in Fusarium sporotrichioides: Origin of the Oxygen Atoms of T-2 Toxin 总被引:6,自引:5,他引:1
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Anne E. Desjardins Ronald D. Plattner Frank Vanmiddlesworth 《Applied microbiology》1986,51(3):493-497
Mass spectral analysis of T-2 toxin formed during the growth of Fusarium sporotrichioides (ATCC 24043) in the presence of H218O showed incorporation of up to three 18O atoms per toxin molecule. The carbonyl oxygens of the acetates at C-4 and C-15 and of the isovalerate at C-8 were derived from H2O. Toxin formed in the presence of 18O molecular oxygen incorporated up to six 18O atoms per toxin molecule. The overall incorporation was 78 and 92% of toxin molecules labeled for H218O and 18O2 labeled samples, respectively. The oxygens of position 1, the 12,13-epoxide, and the hydroxyl groups at C-3, C-4, C-8, and C-15 were all derived from molecular oxygen. 相似文献
10.
《Bioscience, biotechnology, and biochemistry》2013,77(7):1276-1280
An enzyme that catalyzed the deamination of adenosine 3′-phenylphosphonate was purified from squid liver to homogeneity as judged by SDS-PAGE. The molecular weight of the enzyme was estimated to be 60,000 by SDS-PAGE and 140,000 by Sephadex G-150 gel filtration. The enzyme deaminated adenosine, 2′-deoxyadenosine, 3′-AMP, and 2′,3′-cyclic AMP, but not adenine, 5′-AMP, 3′,5′-cyclic AMP, ADP, or ATP. The apparent Km and Vmax at pH 4.0 for these substrates were comparable (0.11-0.34mM and 179-295 μmol min?1 mg?1, respectively). The enzyme had maximum activity at pH 3.5-4.0 for adenosine 3′-phenylphosphonate, at pH 5.5 for adenosine and 2′-deoxyadenosine, and at pH 4.0 for 2′,3′-cyclic AMP and 3′-AMP when the compounds were at concentration of 0.1 mM. The Km at 4.0 and 5.5 for each substrate varied, but the Vmax were invariant. These results indicated that the squid enzyme was a novel adenosine (phosphate) deaminase with a unique substrate specificity. 相似文献
11.
Cong Jiang Robert J. Suhadolnik David C. Baker 《Nucleosides, nucleotides & nucleic acids》2013,32(3):271-294
Abstract [2′-18O]- and [3′-18O]-Adenosine and [2′-18O]- and [3′-18O]-9-(β-D-arabinofuranosyl) adenine were synthesized from?appropriate nucleoside precursors. The sites of 18O-incorporation were determined by mass spectrometry. 18O-Induced 13C NMR shifts were measured for 2′-and 3′-labeled adenosines as 1.2 and 1.6 Hz, respectively. 相似文献
12.
C Soler-Argilaga R L Russell M Heimberg 《Biochemical and biophysical research communications》1977,74(4):1340-1347
Livers from fed male rats were perfused with O2′-monobutyryl guanosine 3′,5′-cyclic monophosphate. The output of triglyceride was reduced, while output of ketone bodies and glucose was stimulated by 10?4M monobutyryl guanosine 3′,5′-cyclic monophosphate. No effect was observed with 10?5 M nucleotide. Monobutyryl guanosine 3′,5′-cyclic monophosphate did not affect uptake of free fatty acids. In these respects, monobutyryl guanosine 3′,5′-cyclic monophosphate mimics the effects of dibutyryl adenosine 3′,5′-cyclic monophosphate, although the guanylic nucleotide seems to be less potent than the adenosine 3′,5′-cyclic monophosphate derivative. 相似文献
13.
R. Thomas Solsten James A. Mccloskey Karl H. Schram 《Nucleosides, nucleotides & nucleic acids》2013,32(1):57-64
Abstract A facile method for the synthesis of highly enriched 18O labeled pyrimidine ribonucleosides is described using uridine as a model compound. The isotopic label may be selectively incorporated into the base moiety at O2 or into the ribose portion of the molecule at the 5′ position. In addition, both positions may be labeled and this is the first report of a method for labeling of both the base and sugar moieties of pyrimidine ribonucleosides. The site and level of isotope incorporation may be determined mass spectrometrically. 相似文献
14.
Two new adenosine analogs, 2′-(2-bromoethyl) adenosine monophosphate and 3′-(2-bromoethyl) adenosine monophosphate, were synthesized, purified by semipreparative high-pressure liquid chromatography, and completely characterized. A new synthesis of 5′-(2-bromoethyl) adenosine monophosphate is presented which facilitates the preparation of radioactive reagent with label either in the ethyl group or the purine ring of the nucleotide derivative. The reactive moiety of these derivatives, a bromoalkyl group, has the ability to react with the nucleophilic side chains of several amino acids. The second-order, pH-independent rate constants for reaction with the side chains of the amino acids cysteine, lysine, histidine, and tyrosine were determined as 3×10?4, 6×10?6, 3×10?7, and <1×10?7 M?1 sec?1, respectively. These data could be use in estimating the rate enhancement observed in modification of a protein by these affinity-labeling reagents. 5′-(S-(2-hydroxyethyl)cysteine) adenosine monophosphate, the derivative expected from exhaustive digestion of protein in which a cysteinyl residue is modified by 5′-(2-bromoethyl) adenosine monophosphate, and S-2-hydroxyethyl)cysteine, the derivative anticipated upon acid hydrolysis of such a modified protein, were synthesized, characterized, and their elution positions from an amino acid analyzer determined. These bromoethyl AMP derivatives are potential affinity labels for enzymes that bind 2′-, 3′-, or 5′-nucleotides such as TPN, coenzyme A, or ADP, respectively. 相似文献
15.
W. Koziolkiewicz J. Pankowski A. Janecka 《Preparative biochemistry & biotechnology》2013,43(6):471-478
A new chemical method for the synthesis of adenosine 5′-γ-[32p] triphosphate has been developed based on the reaction of adenosine 5′- diphosphate with ethyl chloro-formate. The resulting active mixed anhydride was able to react with [32p]-triethylammonium orthophosphate to give γ-[32p]atp. 相似文献
16.
Thymidylate kinase from the livers of 18-day-old chick embryos was concentrated 423-fold. The purification procedure included acid precipitation, ammonium sulfate fractionation, gel filtration on Sephadex G-100 and G-75 Super Fine, and ion-exchange chromatography on Diethylaminoethyl Sephadex A-50. This enzyme was found to be very labile but could be stabilized for long periods of time by its substrate (thymidine 5′-monophosphate) in the presence of 2-mercaptoethanol. Enzymes responsible for the formation of thymidine 5′-diphosphate and thymidine 5′-triphosphate, respectively, were separated during fractionation procedures. Thymidylate kinase from chick embryo liver was found to be a single protein having a molecular weight of approximately 46,000, Michaelis constant approximately 8 × 10?5m, and a broad pH optimum between 6.6 and 8.6. A 2–3 mm requirement of Mg2+ above the adenosine 5′-triphosphate concentration was shown to be necessary for maximum enzyme activity. The enzyme appears to be competitively inhibited by thymidine, thymidine 5′-diphosphate, and thymidine 5′-triphosphate and noncompetitively inhibited by adenosine 5′-diphosphate.Thymidylate kinase enzymes isolated from two stages of developing embryonic liver and adult chick liver were shown to be identical. 相似文献
17.
MEDIATION BY β-ADRENERGIC RECEPTORS OF EFFECT OF NOREPINEPHRINE ON PINEAL SYNTHESIS OF [14 C]SEROTONIN AND [14 C]MELATONIN 总被引:4,自引:0,他引:4
Rat pineal organs maintained in organ culture converted [14C]tryptophan to [14C]serotonin and [14C]melatonin. The synthesis of both indoles was stimulated by the presence of norepinephrine or dibutyryl adenosine 3′,5′-monophosphate. This effect of norepinephrine could be blocked by the α-adrenergic blocking drug, propranolol, but was not modified by the a-adrenergic blocking agent, phenoxybenzamine. Neither blocking agent modified the pineal response to dibutyryl adenosine 3′,5′-monophosphate. Unlike dibutyryl adenosine 3′,5′-monophosphate, the naturally occurring adenosine phosphates did not stimulate synthesis of [14C]melatonin in vitro. 相似文献
18.
Uridylyl 3′-5′[14C] adenosine and uridylyl 2′-5′[14C] adenosine penetrate into rabbit blood cell sap at the same rate. No enzymatic or chemical hydrolysis of the dinucleoside monophosphates was observed. 相似文献
19.
《Inorganica chimica acta》1986,119(2):165-169
Complexes of diphosphaferrocenes have been prepared using (a) Lewis acids BF3·Et2O, A1C13 and (b) Cu(I) and Ag(I) salts. The 31P spectra showed that BF3·Et2O complexes at phosphorus (characterised by a large downfield shift of 103 ppm) whereas all the other adducts involved binding at iron (characterised by large upfield shifts of 36–94 ppm). Deep purple adducts were isolated and characterised for the reaction of 2, 2′, 5, 5′-tetraphenyldipho sphaferrocene with silver trifluoroacetate and triflate and also with copper(I) iodide. Similar complexes were isolated from 3, 3′, 4, 4′-tetramethyldiphosphaferrocene. 57Fe Mössbauer spectroscopy of the adducts showed that unlike the ferrocene system, quadrupole splittings generally decreased on iron complexation. The results are discussed in terms of current MO theory of ferrocene and diphosphaferrocene. 相似文献
20.
Liver calciferol 25-hydroxylase activity of vitamin-D deficient rats was enhanced 24 hours following the intravenous injection of N6-2′-O-dibutyryl adenosine 3′,5′-monophosphate. Sodium butyrate administered in the same way had no effect on this enzyme system. Administration of actinomycin D with N6-2′-O-dibutyryl adenosine 3′,5′-monophosphate abolished the stimulatory effect of the cyclic nucleotide. Direct addition to the incubation medium of adenosine 3′,5′-cyclic monophosphate or of its dibutyryl derivative did not influence the hepatic conversion of cholecalciferol to 25-hydroxycholecalciferol. These results suggest a possible role for the cyclic nucleotide in the regulation of this enzyme system. 相似文献