Mixture Of Adenosine Research Articles

Microchip-Grafted P(NIPAAm-co-VPBA) with Thermoresponsive Boronate Affinity for Capture–Release of cis-Diol Biomolecules

Based on the successful graft of P(N-isopropylacrylamide-4-vinylphenylboronic acid) [P(NIPAAm-co-VPBA)] on glass substrates by surface-initiated atom transfer radical polymerization, a microfludic chip with the performance of thermoresponsive boronate affinity was fabricated and was used for capture–release of the cis-diol biomolecule adenosine. The copolymers modified successfully on the surface of glass substrate were characterized by Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy. The results demonstrated that, by simply adjusting the temperature from 4 to 55 °C, the microchip grafted with P(NIPAAm-co-VPBA) was specific to the cis-diol-containing molecules, and can selectively and quickly realize the capture and release of the cis-diol biomolecule adenosine from the mixture of adenosine and deoxyadenosine, which was validated by high performance liquid chromatography/electronic spray ion–ion trap mass spectrometry (HPLC/ESI–ion trap MS). Moreover, less than 10 min was taken from injection to the collection of the sample at the end of the channel. With further development, the P(NIPAAm-co-VPBA)-grafted microchip with high selectivity and repeatability may be chosen as a promising tool for the enrichment of the cis-diol-containing biomolecules, such as glycoproteins, carbohydrates, glycosylated peptides, nucleosides, etc.

Supramolecular Polymeric Chemosensor for Biomedical Applications: Design and Synthesis of a Luminescent Zinc Metallopolymer as a Chemosensor for Adenine Detection

Adenine is an important bio-molecule that plays many crucial roles in food safety and biomedical diagnostics. Differentiating adenine from a mixture of adenosine and other nucleic bases (guanine, thymine, cytosine, and uracil) is particularly important for both biological and clinical applications. A neutral Zn(II) metallosupramolecular polymer based on acyl hydrazone derived coordination centres (P1) were generated through self-assembly polymerization. It is a linear coordination polymer that behaves like self-standing film. The synthesis, (1)H-NMR characterization, and spectroscopic properties of this supramolecular material are reported. P1 was found to be a chemosensor specific to adenine, with a luminescent enhancement. The binding properties of P1 with common nucleic bases and nucleosides reveal that this supramolecular polymer is very selective to adenine molecules (~20 to 420 times more selectivity than other nucleic bases). The formation constant (K) of P1 to adenine was found to be log K = 4.10 ± 0.02. This polymeric chemosensor produces a specific response to adenine down to 90 ppb. Spectrofluorimetric and (1)H-NMR titration studies showed that the P1 polymer allows each Zn(II) coordination centre to bind to two adenine molecules through hydrogen bonding with their imine and hydrazone protons.

Microelectrode Sensing of Adenosine/Adenosine‐5′‐triphosphate with Fast‐Scan Cyclic Voltammetry

AbstractAdenosine and adenosine‐5′‐triphosphate (ATP) are important extracellular signaling molecules. Here, we studied adenosine and ATP using fast‐scan cyclic voltammetry at carbon‐fiber microelectrodes. Although ATP and adenosine have similar oxidation potentials, ATP oxidation current was highly dependent on buffer pH and divalent cation concentrations but adenosine current was not. Therefore, they can be distinguished by adding a divalent cation chelator or calibrating electrodes at different pH values. The enzymatic degradation of adenosine by adenosine deaminase was monitored in a mixture of adenosine and ATP in presence of EDTA (ethylenediaminetetraacetate). This sensing method is promising for enzyme kinetics or in vitro studies.

Abiogenic photochemical synthesis on surface of meteorites and other small space bodies

Abstract The abiogenic photochemical synthesis of complex biochemical compounds on the surface of small bodies in our Solar system was examined. Hydrated minerals are found within a chondrite matrix of meteorites together with significant amounts of organic matter. Clays are likely to have formed when water was present on parent meteoritic bodies. In order to verify the existence of a relationship between abiogenic synthesis of nucleotides and inorganic components of the meteorites, we have investigated possible abiogenic reactions associated with different clay (montmorillonite, kaolinite) and a basaltic one (Tyatya’s volcanic ash) under action of open space energy sources as a model of different exobiological environments on the surface of small space bodies. The abiogenic synthesis of natural adenine nucleotides from a mixture of adenosine and inorganic phosphate has been observed following irradiation with VUV light in the presence of different mineral samples. The yields of the products (5′AMP, 2′AMP, 3′AMP, 2′3′cAMP and 3′5′cAMP) depended on irradiation time and kinds of minerals used. The discovery that meteoritic organic compounds may be trapped and protected within a clay mineral matrix has implications for our understanding of prebiotic molecular evolution in the early Solar system. Clay minerals may also have concentrated organic compounds thereby promoting polymerization reactions. An adsorption/binding of nucleic acids components by clay crystals could change the electron distribution and/or the conformation of the molecules. The remnant water molecules in the clay sheets also could influence the course of the reaction. Clay immobilization of phosphate could play an important role in this reaction. Chondritic material could have been a common component of the inner Solar system shortly after its formation and the biologically useful products of clay mineral–organic matter interactions could have also widespread, and delivered to planetary surfaces through the accretion of carbonaceous asteroids.

Identification of substrates for adenosine deaminases that act on RNA.

Adenosine deaminases that acts on RNA (ADARs) are RNA-editing enzymes that convert adenosine to inosine in double-stranded RNA. This chapter provides a detailed protocol for identifying inosine-containing RNAs. Candidate ADAR substrates are identified by cleaving poly (A)+ RNA specifically after inosine and using differential display to detect cleaved molecules. To confirm the presence of inosine, each individual candidate substrate is amplified by reverse transcriptase polymerase chain reaction (RT-PCR) and the PCR product is directly sequenced. Sites that contain inosine at the RNA level appear as a mixture of adenosine and guanosine in the cDNA. The relative peak areas provide an estimate of the extent of editing at each site.

Concurrent analysis of nucleoside reverse transcriptase inhibitors in a pool of endogenous nucleosides by short-end injection-capillary electrochromatography on a beta-cyclodextrin-bonded stationary phase.

As part of our on-going study of the analysis of anti-human immunodeficiency virus (HIV) nucleosides, a capillary electrochromatography (CEC) method has been developed for the concurrent analysis of nucleoside HIV reverse transcriptase inhibitors (NRTIs) in a pool of endogenous nucleosides. Up to now, beta-cyclodextrin-bonded silica stationary phases have mainly been dedicated to the separation of enantiomers; however, these polysaccharides can be also be used in achiral way. This work aims at showing how CEC performed on a beta-cyclodextrin-bonded silica stationary phase can be used to concurrently resolve zidovudine (AZT), lamivudine (3TC), didanosine (ddA) and its administrated form (ddI), stavudine (d4T) and hivid (ddC) in a mixture of adenosine (A), cytidine (C), guanosine (G), thymidine (T) and uridine (U). The influence of several parameters (pH buffer, ionic strength, acetonitrile content, temperature and voltage) on both the retention times and the retention factors has been investigated using the short-end injection technique to achieve baseline separation in a short-time analysis before quantitation. Moreover, the retention factors of the charged solutes in short-end injection-CEC were calculated using theoretically derived equations, allowing for the actual voltage drop in the packed section of the semipacked CEC capillary.

The Kinetics of Substitution Reactions of Mixed Platinum(II)-Bis(nucleoside) Complexes in Aqueous Solution in the Presence of Thiourea; X-Ray Crystal Structure Determination ofcis-[Pt(NH3)2(adenosine-N7)2](ClO4)2⋅3.5 H2O

In aqueous solution, bis(nucleoside) complexes formed by the reaction of cis-[Pt(NH3)2(H2O)2]2+ with an excess of either adenosine (ado) or a mixture of adenosine and guanosine (guo) undergo a slow N7--> N1 linkage isomerisation in the adenine moiety. The isomerisation probably involves the breaking and reformation of Pt-nucleoside bonds, thus favouring the more stable N1 binding mode of the adenine base. Dynamic processes due to the presence of adenosine in the platinum coordination sphere are slow on the NMR time scale. The N7 binding mode of PtII in cis-[Pt(NH3)2(ado-N7)2](ClO4)2. 3.5H2O was confirmed by X-ray crystal structure analysis. In both of the crystallographically independent cations, the PtII coordination sphere is almost ideally square planar, with typical Pt-N bond lengths and angles. The most significant difference between the two cations lies in the sugar conformation of the coordinated nucleosides. In one cation, both have an anti (-ap) conformation, whilst in the other cation one has an anti (-ap) conformation and the other a syn (+sc) conformation stabilised by a relatively strong H-bond. Substitution of the nucleoside(s) by thiourea follows an associative mechanism with only a negligible contribution by the solvent path. For symmetric complexes, the order of lability of different binding modes is ado-N1 <guo-N7 < ado-N7 for substitution of the first nucleoside, whereas for the second nucleoside it is guo-N7 < ado-N1 < ado-N7. For asymmetric complexes, the concomitant cleavage of different PtII-nucleoside bonds can be explained by two parallel reaction pathways. The change in the PtII coordination sphere affects the lability of the coordinating nucleosides in a different manner. The ado-N1 binding mode renders all binding modes less labile, whereas the ado-N7 mode has the opposite effect, and the guo-N7 mode increases the lability of the ado-N1 mode but decreases that of the ado-N7 mode. The mixed-ligand complex with (ado-N7)(guo-N7) mode is far more susceptible to attack by thiourea than the symmetric (guo-N7)2 species. These two species can be considered as models for the two most abundant Cisplatin-DNA adducts.

Abiogenic synthesis of nucleotides in conditions of space flight of the biosputnik “BION-11”

The space satellite's surface can be looked at as a model of the small bodies in the Solar system, such as comets, carbonaceous chondrites and interplanetary dust particles which are rich in complex organic compounds. It is important to test how far the process of chemical evolution could develop on the surface of these bodies. The solid films from mixtures of adenosine, deoxyadenosine, cytidine or thymidine and NaH 2PO 4 were exposed to open space condition in flight experiment on board of “BION—11” satellite. (The time of flight was 14 days, temperature changed from −30 up to +100°C). The abiogenic synthesis of nucleotides has been observed. The summary yields were: for adenosine—5.8%, for deoxyadenosine—2.3%, for cytidine—4.7% and for thymidine —2.0%. Our experiment indicates that nucleotides could be synthesized in an early stage of the Solar system evolution and safely transported to the Earth by comets, asteroids and dust particles.

Response of urinary and plasma purine derivatives to various rates and infusion patterns of purines in sheep nourished by intragastric infusion

The effects of exogenous purine supply on plasma concentration and urinary excretion of purine derivatives (PD), which include allantoin, uric acid, xanthine and hypoxanthine, were studied. Five sheep, totally nourished by intragastric infusion of volatile fatty acids and casein, were given an abomasal infusion of a mixture of adenosine and guanosine at three levels (5·0, 10·0 and 20·0 mmol/day) each in four infusion patterns (as one, two, or four 3-h infusion periods per day or infused continuously, P1 to P4 respectively). Urine was collected hourly over 24 h, and plasma samples were collected hourly for 7 h from the start of purine infusion. Both the plasma concentration of PD and its urinary excretion changed rapidly in response to the start and termination of purine infusion with a lag time of 2–3 h. Individual sheep differed considerably in the relative proportions of the different purine derivatives in the urine. The endogenous urinary PD excretion averaged 176 (±S.E. 28) μmol/kg W0·75 per day. Daily PD excretion in urine increased with the amount of purine infusion, but at each level the output decreased significantly in a gradient from P1 to P4. The response of total PD excretion (Y, mmol/day) to daily purine input (X, mmol/day) was predictable and followed the equation: Y=0·81 (±0·02)X+3·07(±0·81) × (u e−0·27X/u +1−u), where u is the duration over which the daily input was infused expressed as a proportion of 24 h. The recovery of the infused purines averaged 81%. When the infusion was given continuously, plasma PD concentration was relatively stable and was linearly correlated with the purine entry rate and daily PD excretion in the urine. The estimated glomerular filtration rate was 150 (±S.E. 16) litres/day and the estimated tubular transport maximum was 2·6 (±S.E. 1·3) mmol/day. It is concluded that due to the rapidity in the response of plasma and urinary PD to changes in the exogenous purine supply, spot measurements of PD in urine or plasma can be of no value for the estimation of exogenous purine uptake unless the purine supply is relatively constant throughout the day. Daily PD excretion in urine related to the exogenous purine uptake in a predictable and reproduceable manner and provides a reliable index for the estimation of the exogenous purine uptake.

Aminolysis and alkaline hydrolysis of protected 1-hydroxybenzo-triazol-1-yl esters of adenosine 5′-phosphorothioate and -phosphorodithioate

When 2′,3′-bis-O-(methoxyacetyl)-6-N-(9-phenylxanthen-9-yl)adenosine 9, which was prepared from adenosine in six steps and in ∼ 70% overall yield, was treated with putative tri(benzotriazol-1-yl) phosphorothioate 11 and the products then worked up with aq. triethylamine, the triethylammonium salt of die protected benzotriazol-1-yl ester 6a of adenosine 5′-phosphorothioate was obtained in high yield. The corresponding adenosine 5′-phosphorodithioate derivative 6b was prepared, also in high yield, by a modification of the latter procedure involving work-up with hydrogen sulfide and triethylamine. Reaction between die phosphorothioate derivative 6a and methylamine or morpholine gave the phosphorothioamidates 12a and 13a, respectively, to high yields; in the same way, the phosphorodithioate derivative 6b was converted into the phosphorodithioamidates 12b and 13b. Treatment of the phosphorothioate derivative 6a first with aq. alkali and then with aq. acid gave a mixture of adenosine 5′-phosphorothioate 15a and adenosine 3′,5′-cyclic phosphorothioate 17a. When the phosphorodithioate derivative 6b was treated in the same way, adenosine 3′,5′-cyclic phosphorodithioate 17b was obtained in good yield.

Influence of calcium on the release of endogenous adenosine from spinal cord synaptosomes

Intrathecal administration of Ca 2+ has been shown to produce antinociception which is thought to be partially mediated by the release of adenosine. In the present study we have examined directly the effects of varying Ca 2+ concentrations on the release of endogenous adenosine, measured by HPLC wi fluorescence detection, from rat spinal cord synaptosomes. Although increasing the concentration of extracellular Ca 2+ reduces the total amount of adenosine detected extrasynaptosomally, the component derived from the release of adenosine per se is actually augmented. This release of adenosine occurs from dorsal but not ventral spinal cord synaptosomes and appears to originate from capsaicin-sensitive nerve terminals. The Ca 2+ ionophore A23187 also releases adenosine, but this release is due to the extrasynaptosomal conversion of released nucleotide(s) to adenosine, as it is markedly reduced by ecto-5’-nucleotidase inhibitors. Release of adenosine by A23187 occurs from both the dorsal and ventral spinal cord, and is not capsaicin-sensitive. Ethanol, used as a vehicle for the ionophore, releases adenosine which is a mixture of adenosine and nucleotide from both dorsal and ventral spinal cord synaptosomes. These observations provide direct support for behavioural studies which demonstrate that methylxanthines block antinociception produced by intrathecal administration of Ca 2+.

Column chromatography on polyethylenimine-silica: Rapid resolution of nucleotides and proteins with short columns and low pressures

Silica gel (100–200 mesh) can be coated with a stable layer of crosslinked polyethylenimine (PEI). The resulting material is useful in column chromatography for quantitative separation of adenine nucleotides. For example, 3′:5′-cyclic AMP can be separated from a mixture containing AMP, ADP, and ATP. A mixture of adenosine, AMP, ADP, and ATP can be resolved with quantitative recovery of components. Convenient separation of cytochrome c from albumin illustrates the applicability of this system to protein purification. PEI-Xama silica gel and PEI-glutaraldehyde silica gel have ion-exchange capacities of 0.27 and 0.21 meq/g, respectively. The materials are dimensionally rigid and chemically stable except in alkaline solutions (>pH 10) for prolonged periods.

Isolation and Identification of Hypotensive Substances in Chlorella Extract

We attempted isolation of the hypotensive substance contained in hot water extracts of chlorella raw cells. When chlorella extracts were fractionated by gel filtration, fraction E showed a depressive effect. Blood pressure of SHR and SHRSP showed falls of about 60mmHg at 1 hour after intravenous administration and of 30 to 40mmHg at 2 hours after intragastric administration. Fraction E was subsequently purified by passage through a column of Sephadex G-10, and then crystallized from ethanol. Both the crystalline compound and the mother liquor showed hypotensive effects, but the effect of the latter was more potent. The crystalline compound was identified as adenosine by means of chemical and physical methods, and the mother liquor was considered to be a mixture of adenosine and an unknown compound containing glycine. As a result, the hypotensive effect of fraction E on SHR and SHRSP may be ascribable to adenosine or to an oligopeptide with a molecular weight of approximately 200.

Potentiometric analysis of mixtures of adenosine and guanosine

Potentiometric analysis of mixtures of adenosine and guanosine

Enzymic formation of d-kynurenine from d-tryptophan

An enzyme system that catalyzes the conversion of d-tryptophan to d-kynurenine, presumably via d-formylkynurenine, was studied in the 20,000 g supernatant fraction of homogenates of the rabbit ileum. One mole of oxygen was consumed per mole of substrate utilized, and one mole each of d-kynurenine and formate was produced. The enzyme activity was greatly stimulated by the addition of methylène blue and a DPNH-generating system; the latter can be replaced partially by a mixture of adenosine (or 5′-AMP, cyclic 3′,5′-AMP, or ATP), Mg ++, and catalase. The pH optimum of the reaction lies between 8.0 and 8.5. The reaction was inhibited by the presence of l-tryptophan. For convenience, the enzyme that catalyzes the oxidation of d-tryptophan is tentatively designated as d-tryptophan pyrrolase.

Spore germination in the genus bacillus: the modification of germination requirements as a result of preheating.

Summary: Spore suspensions of Bacillus megaterium germinated spontaneously after heat treatment. The extent of germination depended on the degree of close packing of the suspension, the temperature and duration of heating, and on the presence of water. Spontaneous germination was not inhibited by heating with cyanide, azide, 2:4-dinitrophenol or sodium iodoacetate, but was significantly inhibited by sodium fluoride. Freshly harvested spores of a laboratory strain of Bacillus cereus required either inosine or a mixture of alanine + tyrosine + adenosine for optimal germination. After prolonged storage or a short heat treatment, adenosine alone stimulated rapid and complete germination. Heat activation did not occur in the absence of water. It was inhibited to some extent by sodium fluoride. Similar results were obtained with B. cereus, NCTC 8035. After preheating, spores of a virulent and an avirulent strain of Bacillus anthracis germinated more rapidly and completely in a mixture of adenosine + tyrosine + alanine, but not in adenosine alone. Inosine stimulated rapid and complete germination of heated suspensions, and was consistently more effective than adenosine. Adenosine deaminase activity has been found in extracts from resting spores of the laboratory B. cereus and the avirulent strain of B. anthracis but not in B. megaterium.