Formation of the imidazolides of dinucleotides under potentially prebiotic conditions

Summary Imidazolides of dinucleotides such as ImpApA can be formed from the corresponding dinucleotides in a two-stage process, which gives up to 15% yields under potentially prebiotic conditions. First a solution of the dinucleotide and sodium trimetaphosphate is dried out at constant temperature and humidity. This produces polyphosphates such as pnApA in excellent yield (80%). The products are dissolved in water, imidazole is added, and the solution is dried out again. This yields the 5-phosphorimidazolides.Abbreviations P₃! trimetaphosphate - A adenosine - U uridine - EDTA ethylenediaminetetraacetic acid - Ap adenosine 2(3)-phosphate - Ap! adenosine cyclic 2:3-phosphate - pA adenosine 5-phosphate - pA²p adenosine 2, 5-diphosphate - pA³p adenosine 3, 5-diphosphate - pAp! 5-phospho-adenosine cyclic 2:3-phosphate - ATP adenosine 5-triphosphate - ImpA adenosine 5-phosphorimidazolide - A²pA adenylyl-[25]-adenosine - A³pA adenylyl-[35]-adenosine - A²pU adenylyl-[25]-uridine - A³pU adenylyl-[35]-uridine - pA²pA 5-phosphoadenylyl-[25]-adenosine - pA³pA 5-phospho-adenylyl-[35]-adenosine - pA²pU 5-phospho-adenylyl-[25]-uridine - pA³pU 5-phospho-adenylyl-[35]-uridine - pApN (N= A, U) 5-phosphate of a dinucleoside phosphate - p_nApN (N = A, U; n = 2, 3, 4.) 5-polyphosphate of a dinucleoside phosphate - ImpA²pA imidazolide of pA²pA - ImpA³pA imidazolide of pA³pA - ImpA²pU imidazolide of pA²pU - ImpA³pU imidazolide of pA³pU - ImpApN imidazolide of pApN     

Observations on the reduction of non-activated carboxylates by Clostridium formicoaceticum with carbon monoxide or formate and the influence of various viologens

Crude extracts or supernatants of broken cells of Clostridium formicoaceticum reduce unbranched, branched, saturated and unsaturated carboxylates at the expense of carbon monoxide to the corresponding alcohols. The presence of viologens with redox potentials varying from E ₀=-295 to-650 mV decreased the rate of propionate reduction. The more the propionate reduction was diminished the more formate was formed from carbon monoxide. The lowest propionate reduction and highest formate formation was observed with methylviologen. The carbon-carbon double bond of E-2-methyl-butenoate was only hydrogenated when a viologen was present. Formate as electron donor led only in the presence of viologens to the formation of propanol from propionate. The reduction of propionate at the expense of a reduced viologen can be followed in cuvettes. With respect to propionate Michaelis Menten behavior was observed. Experiments are described which lead to the assumption that the carboxylates are reduced in a non-activated form. That would be new type of biological reduction.Non-standard abbreviations glc Gas liquid chromatography - HPLC high performance liquid chromatography - RP reverse phase; Mediators (the figures in parenthesis of the mediators are redox potentials E ₀ in mV) - CAV²⁺ carbamoylmethylviologen, 1,1-carbamoyl-4,4-dipyridinium dication (E ₀=-296 mV) - BV²⁺ benzylviologen, 1,1-dibenzyl-4,4-dipyridinium dication (E ₀=-360 mV) - MV methylviologen, 1,1-dimethyl-4,4-dipyridinium-dication (E ₀=-444 mV) - DMDQ²⁺ dimethyldiquat, 4,4-dimethyl-2,2-dipyridino-1,1-ethylendication (E ₀=-514 mV) - TMV²⁺ tetramethylviologen, 1,1,4,4-tetramethyl-4,4-dipyridinium dication (E ₀=-550 mV) - PDQ²⁺ propyldiquat, 2,2-dipyridino-1,1-propenyl dication (E ₀=-550 mV) - DMPDQ²⁺ dimethylpropyldiquat, 4,4-dimethyl-2,2-dipyridino-1,1-propenyl dication (E ₀=-656 mV) - PN productivity number=mmol product (obtained by the uptake of one pair of electrons) x (biocatalyst (dry weight) kg)^-1×h^-1     

Serial production of nucleoside-5′-triphosphates and uracil from 3′-mononucleotides by intact yeast cells

Summary Nucleoside-5-triphosphates such as 5-ATP and 5-GTP can be produced efficiently and continuously from 3-mononucleotides such as 3-AMP and 3-GMP by a series of processes consisting of two reaction phases using dried cells of Candida sp. N-25-2 (a hydrocarbon assimilating yeast). Moreover, incidentally to the 5-triphosphates, free uracil is yielded almost stoichiometrically from 3-CMP and 3-UMP which, as is well known, are main concomitant products depolymerized from RNA. Uracil is then also available for many usage.     

The composition of Erythrosins, Fluorescein, Phloxine and Rose Bengal: a study using thin-layer chromatography and solvent extraction

Synopsis Commercial samples of Erythrosin B (CI 45430), Erythrosin Y (CI 45425), Fluorescein (CI 45350), Phloxine (CI 45410) and Rose Bengal (CI 45440) have been analysed by thin-layer chromatography. The Erythrosins were found to be mixtures consisting in the main of 4-iodofluorescein, 4,5-di-iodofluorescein, 2,4,5-triiodofluorescein and 2,4,5,7-tetraiodofluorescein, in some instances together with 2,4,5-tri-iodo-4,5,6,7-tetrachlorofluorescein and 2,4,5,7-tetraiodo-4,5,6,7-tetrachlorofluorescein. Samples of Fluorescein were mixtures of the nominal dye usually with traces of several unidentified, fluorescent components. Those of Phloxine consisted mainly of mixtures of 4-bromo-4,5,6,7-tetrachlorofluorescein, 4,5-dibromo-4,5,6,7-tetrachlorofluorescein, 2,4,5-tribromo-4,5,6,7-tetrachlorofluorescein and 2,4,5,7-tetrabromo-4,5,6,7-tetrachlorofluorescein, often with 4,5,6,7-tetrachlorofluorescein Samples of Rose Bengal were mixtures of 4-iodo-4,5,6,7-tetrachlorofluorescein, 4,5-di-iodo-4,5,6,7-tetrachlorofluorescein, 2,4,5-tri-iodo-4,5,6,7-tetrachlorofluorescein and 2,4,5,7-tetraiodo-4,5,6,7-tetrachlorofluorescein together with some unidentified components.Most of the commercial dye samples gave an insoluble residue when extracted with methanol. This residue was usually inorganic carbonate or halide. Some possible practical consequences of the various impurities are discussed.     

Monomers for Oligonucleotide Synthesis with Linkers Carrying Reactive Residues: II. The Synthesis of Phosphoamidites on the Basis of Uridine and Cytosine and Containing a Linker with Methoxyoxalamide Groups in Position 2′

A convenient preparative synthesis of 2-amino-2-deoxyuridine was developed. Starting from 2-amino-2-deoxyuridine and 2-amino-2-deoxycytidine, monomers for the phosphoamidite oligonucleotide synthesis were obtained that carry a linker with methoxyoxalamide groups in position 2.     

Dephosphorylated oligoadenylates modulate high voltage-activated calcium currents in GH3 cells

Effects of different forms of C2-5A (2,5ApApA; 2,5ApApepoxyA; and 3,5ApApA) on high voltage-activated (HVA) calcium currents in GH3 cells were studied using the whole-cell patch-clamp recording technique. Addition of 10 µM 2,5ApApA, a core (dephosphorylated) oligoadenylate, to the pipette solution induced an increase in HVA calcium current. Ten minutes after the whole-cell configuration was established, the current magnitude was enhanced about twofold compared with that observed at 2 min. High concentration of Mg²⁺ (5 µM) in the pipette solution blocked this effect. 2,5ApA and 3,5ApApA oligoadenylates, and products of 2,5A hydrolysis, adenosine and AMP, did not change the value of HVA current. A chemically modified analog of 2,5ApApA (2,5ApApepoxyA) has been the oligoadenylate most stable under phosphodiesterase action. Addition of 2,5ApApepoxyA to the pipette solution under the same conditions caused a smaller effect than 2,5ApApA did.Neirofiziologiya/Neurophysiology, Vol. 26, No. 6, pp. 405–408, November–December, 1994.     

Nucleoside Phosphorylation: A Feasible Step in the Prebiotic Pathway to RNA

Plausible prebiotic conditions for the phosphorylation of nucleosides by inorganic phosphate were reported by Lohrmann and Orgel in 1971. This reaction was carried out on heated dry films and promoted by urea. The major products formed were nucleoside-2:3 cyclicPs; 5-NMPs and other derivatives were also formed. Minor modifications of the Lohrmann and Orgel system have resulted in the preferential formation of 5-NMPs. In this modified system a 2-fold preference for phosphorylation of the 5-OH group over the 3(2)-OH group was observed and the formation of other derivatives was minimized. The small amounts of bis compounds that were formed in this system could be quantitatively removed by selective binding to the mineral hydroxylapatite at moderate ionic strengths. It was also discovered that under hydrolytic conditions there was a 3:1 preference for removal of phosphates attached to the 3-OH group over the 5-OH group. A recycling procedure for obtaining additional 5-NMPs from bis compounds and 3-NMPs is proposed.     

The influence of increasing chlorine content on the accumulation and metabolism of polychlorinated biphenyls (PCBs) by Paul's Scarlet Rose cells

Four radiolabled congeners of biphenyls with increasing chlorine content (biphenyl; 1-monochlorobiphenyl; 2,2,4,4-tetrachlorobiphenyl; and 2,2,4,4,5,5-hexachlorobiphenyl) were provided to suspension cultures of rose (Rosa sp. cv. Paul's Scarlet) for 4 days. Both the kinetics of ¹⁴C exchange between the cells and medium, and the metabolism of the parent compounds depended on the chlorine content of the congeners. Analysis of both the cells and their medium showed that of the recovered radioactivity 88%, 86%, and 3% of the biphenyl, 1-PCB, and 2,2,4,4-PCB were metabolized respectively to polar and insoluble residue products. The 2,2,4,4,5,5-PCB did not appear to be metabolized.     

Carotenoid pigments of Sorangium compositum (Myxobacterales) including two new carotenoid glucoside esters and two new carotenoid rhamnosides

Summary The carotenoid pigments of the myxobacterium Sorangium compositum were analyzed by chromatographical and chemical techniques and by visible, infra red, and mass spectroscopy. Besides -carotene, neurosporene, torulene, lycopene, and 1,2-dihydro-1-hydroxy--carotene, four new carotenoid glycosides were found. These pigments were identified as 1,2-dihydro-1-hydroxy-torulene glucoside ester (I), 1,2-dihydro-3,1-dihydroxy-torulene glucoside ester (III), 1,2-dihydro-1-hydroxy-torulene rhamnoside (II), and 1,2-dihydro-3,1-dihydroxytorulene rhamnoside (IV).Fifth communication on the carotenoids of myxobacteria. Fourth communication see Arch. Mikrobiol. 76, 364–380 (1971).     

Polymerization of nucleotide analogues I: Reaction of nucleoside 5′-phosphorimidazolides with 2′-amino-2′-deoxyuridine

Summary 2-Amino-2-deoxyuridine reacts efficiently with nucleoside 5-phosphorimidazolides in aqueous solution. The dinucleoside monophosphate analogues were obtained in yields exceeding 80% under conditions in which little reaction occurs with the natural nucleosides.In a similar way, the 5-phosphorimidazolide of 2-amino-2-deoxyuridine undergoes self-condensation in aqueous solution to give a complex mixture of oligomers.The phosphoramidate bond in the dinucleoside monophosphate analogues is stable for several days at room temperature and pH 7. The mechanisms of their hydrolysis under acidic and alkaline conditions are described.Abbreviations A adenosine - C cytidine - G guanosine - U uridine - T thymidine - U_{N 3} 2-azido-2-deoxyuridine - U_{NH 2} 2-amino-2-deoxyuridine - ImpA adenosine 5-phosphorimidazolide - ImpU uridine 5-phosphorimidazolide - ImpU_{N 3} 2-azido-2-deoxyuridine 5-phosphorimidazolide - ImpU_{NH 2} 2-amino-2-deoxyuridine 5-phosphorimidazolide - pA adenosine 5-phosphate - pU uridine 5-phosphate - pU_{N 3} 2-azido-2-deoxyuridine 5-phosphate - pU_{NH 2} 2-amino-2-deoxyuridine 5-phosphate - UpA uridylyl-[35]-adenosine - UpU uridylyl-[35]-uridine - U_NpA adenylyl-[52]-2-amino-2-deoxy-uridine - U_NpU uridylyl-[52]-2-amino-2-deoxyuridine (pU_N)_n n=2,3,4 [25]-linked oligomers of pU_{NH 2} poly(A) polyadenylic acid - Im imidazole - MeIm l-methylimidazole     

Adenosine-5′-phosphosulfate (APS) as sulfate donor for assimilatory sulfate reduction in Rhodospirillum rubrum

Crude extracts of Rhodospirillum rubrum catalyzed the formation of acid-volatile radioactivity from (³⁵S) sulfate, (³⁵S) adenosine-5-phosphosulfate, and (³⁵S) 3-phosphoadenosine-5-phosphosulfate. An enzyme fraction similar to APS-sulfotransferases from plant sources was purified 228-fold from Rhodospirillum rubrum. It is suggested here that this enzyme is specific for adenosine-5-phosphosulfate, because the purified enzyme fraction metabolized adenosine-5-phosphosulfate, however, only at a rate of 1/10 of that with adenosine-5-phosphosulfate. Further, the reaction with 3-phosphoadenosine-5-phosphosulfate was inhibited with 3-phosphoadenosine-5-phosphate whereas this nucleotide had no effect on the reaction with adenosine-5-phosphosulfate. For this activity with adenosine-5-phosphosulfate the name APS-sulfotransferase is suggested. This APS-sulfotransferase needs thiols for activity; good rates were obtained with either dithioerythritol or reduced glutathione; other thiols like cysteine, 2-3-dimercaptopropanol or mercaptoethanol are less effective. The electron donor methylviologen did not catalyze this reaction. The pH-optimum was about 9.0; the apparent K _m for adenosine-5-phosphosulfate was determined to be 0.05 mM with this so far purified enzyme fraction. Enzyme activity was increased with K₂SO₄ and Na₂SO₄ and was inhibited by 5-AMP. These properties are similar to assimilatory APS-sulfotransferases from spinach and Chlorella.Abbreviations APS adenosine-5-phosphosulfate - PAPS 3-phosphoadenosine-5-phosphosulfate - 5-AMP adenosine-5-monophosphate - 3-AMP adenosine-3-monophosphate - 3-5-ADP 3-phosphoadenosine-5-phosphate (PAP) - DTE dithiorythritol - GSH reduced glutathione - BAL 2-3-dimercaptopropanol     

Sugar conformation of a stereospecific 2′-R or 2′-S deuterium-labeled DNA decamer studied with proton-proton J coupling constants

The sugar conformation of a DNA decamer was studied with proton-proton ³J coupling constants. Two samples, one comprising stereospecifically labeled 2-R-²H for all residues and the other 2-S-²H, were prepared by the method of Kawashima et al. [J. Org. Chem. (1995) 60, 6980–6986; Nucleosides Nucleotides (1995) 14, 333–336], the deuterium labeling being highly stereospecific 99% for all 2-²H, 98% for 2-²H of A, C, and T, and 93% for 2-²H of G). The ³J values of all H1-H2 and H1-H2 pairs, and several H2-H3 and H2-H3 pairs were determined by line fitting of 1D spectra with 0.1–0.2 Hz precision. The observed J coupling constants were explained by the rigid sugar conformation model, and the sugar conformations were found to be between C3-exo and C2-endo with _m values of 26° to 44°, except for the second and 3 terminal residues C2 and C10. For the C2 and C10 residues, the lower fraction of S-type conformation was estimated from J_H1H2 and J_H1H2 values. For C10, the N–S two-site jump model or Gaussian distribution of the torsion angle model could explain the observed J values, and 68% S-type conformation or C1-exo conformation with 27° distribution was obtained, respectively. The differences between these two motional models are discussed based on a simple simulation of J-coupling constants.     

A novel PH-CT-COSY methodology for measuring JPH coupling constants in unlabeled nucleic acids. Application to HIV-2 TAR RNA

A quantitative analysis of J_PH scalar couplings in nucleic acids is difficult due to small couplings to phosphorus, the extreme overlap of the sugar protons and the fast relaxation of the spins involved in the magnetization transfer. Here we present a new methodology that relies on heteronuclear Constant Time Correlation Spectroscopy (CT-COSY). The three vicinal ³J_PH3, ³J_PH5 and ³J_PH5 scalar couplings can be obtained by monitoring the intensity decay of the P_i-H3_{i – 1} peak as a function of the constant time T in a 2D correlation map. The advantage of the new method resides in the possibility of measuring the two ³J_PH5 and ³J_PH5 scalar couplings even in the presence of overlapped H5/H5 resonances, since the quantitative information is extracted from the intensity decay of the P-H3 peak. Moreover, the relaxation of the H3 proton is considerably slower than that of the H5/H5 geminal protons and the commonly populated conformations of the phosphate backbone are associated with large ³J_PH3 couplings and relatively small ³J_{PH5 / H5}. These two facts lead to optimal signal-to-noise ratio for the P-H3 correlation compared to the P-H5/H5 correlation.The heteronuclear CT-COSY experiment is suitable for oligonucleotides in the 10–15 kDa molecular mass range and has been applied to the 30mer HIV-2 TAR RNA. The methodology presented here can be used to measure P-H dipolar couplings (D_PH) as well. We will present qualitative results for the measurement of P-H_base and P-H2 dipolar couplings in the HIV-2 TAR RNA and will discuss the reasons that so far precluded the quantification of the D_PHs for the 30mer RNA.     

Virulence as a consequence of genome instability of a novel temperate bacteriophage, ΦRsG1, of Rhodobacter sphaeroides Y

A novel temperate bacteriophage, designated RsG1, was isolated from Rhodobacter sphaeroides Y (previously designated Rhodopseudomonas sphaeroides) following exposure to mitomycin C. The phage morphology, as revealed from electron microscopy, showed a hexagonal head (90 by 46.5 nm) connected with a tail (116 by 9.4 nm), to which a collar was proximally attached. A morphologically similar phage was also produced by spontaneous lysis of the cells. While RsG1 did not grow on any other bacterial strain tested, spontaneously produced phage particles propagated (and formed plaques) on R. sphaeroides Y still carrying RsG1 in the prophage state. The genome of RsG1 consisted of double stranded linear DNA with cohesive ends and a GC-content of 71.8 mol%. The DNA molecules formed circles in vitro with a mean contour length of 17.18±0.4 m, which corresponds to a size of 49 kbase pairs (kb). On the other hand, DNA extracted from the virulent phage particles was heterogeneous and consisted of two DNA species of different size, occurring in a ratio of about 1:1. These molecules also circularized having contour lengths of 17.18±0.4 m and 14.02±0.41 m corresponding to 49 and 40 kb, respectively. Restriction digest analysis of the two DNA species and DNA from RsG1 indicated that they are similar, and allowed the indentification of an 11.5 kb EcoRI fragment that carries the cohesive ends. Because DNA from RsG1 and the 49 kb DNA of the virulent phage particles were indistinguishable with the criteria applied, it is suggested that phage particles containing the 40 kb DNA represent the virulent type of phage, termed RsG1.1.     

The reduction of tetrazolium salts by plant mitochondria

Summary Data has been obtained concerning the reduction of tetrazolium salts by mitochondria isolated from Jerusalem artichoke tubers with succinate as the substrate using a direct recording spectrophotometric method of assay. ATP was found to increase the rate of reduction of the tetrazolium salts, this being independent of the effect ATP had on the rate of oxygen uptake. The magnitude of the stimulation by ATP depended on the concentration of tetrazolium salts present and under certain circumstances was suppressed by the addition of azide and cyanide. The sites at which the tetrazolium salts were reduced along the electron transport chain were investigated. The role of ATP has been discussed in relation to the mechanism of tetrazolium reduction.Abbreviations TTC 2,3,5-triphenyl-2,1,3,4-tetrazolium chloride - BT 5,5-diphenyl-3,3-(3,3-dimethoxy-4,4-diphenylene)-ditetrazolium chloride - NT 2,2,5,5-tetraphenyl-3,3-(p-diphenylene)-ditetrazolium chloride - MTT 3-(4,5-dimethyl thiozolyl-2)-2,5-diphenyl tetrazolium bromide - INT 2-(p-iodophenyl)-3-p-dinitrophenyl-3-p-nitrophenyl-5-phenyl tetrazolium chloride - NBT 2,2-dinitrophenyl-5,5-diphenyl-3,3-dimethoxy-4,4-diphenylene)-ditetrazolium chloride - TNBT 2,2-5,5-tetra-p-nitrophenyl-3,3-dimethoxy-4,4-diphenylene) ditetrazolium chloride     

Template-directed reactions of aminonucleosides

Summary We have studied the reactions between adenosine 5-phosphorimidazolide and 9-(2-amino-2-deoxyxylofuranosyl) adenine (I) or 3-methylamino-3-deoxyadenosine (II), both with and without a poly (U) template. We find that both amino compounds react much more rapidly than does adenosine, in the absence of a template. The rate of reaction is greatly enhanced by a poly (U) template in the case of I, but the enhancement is slight in the case of II.Abbreviations A adenosine - xylo A_NH2 9-(2-amino-2-deoxy--D-xylofuranosyl) adenine - A_NHMe 3-methylamino-3-deoxyadenosine - ImpA adenosine 5-phosphorimidazolide - A³ pA adenylyl-[35]-adenosine - A² pA adenylyl-[25]-adenosine - U_NPA adenylyl-[52]-2-amino-2-deoxyuridine - xylo A_NPA 9-[adenylyl-(52)-2-amino-2-deoxy--D-xylofuranosyl]adenine - A_(NMe)pA adenylyl-[53]-3-methylamino-3-deoxyadenosine - pA adenosine 5phosphate - AppA P₁, P₂-diadenosine 5pyrophosphate - (pA)_n n = 2, 3 [2-5]-linked oligomers of pA - A² pA² pA [2-5]-linked trinucleoside diphosphate of A - poly (U) polyuridylic acid     

A ‘minimum stress inflexion’ in relation to environmental and biotic influences on the dynamics of subtidal encrusting communities?

The sedentary fauna of sublittoral boulders was studied at five sites with very different environmental conditions within Lough Hyne Marine Nature Reserve (51° 30 N, 9° 18 W). The degree of competition was assessed through the construction of competitive hierarchies built up from the results of nearly 3000 interactions between organisms. Communities at all sites were predominantly hierarchically organised with few stand-offs recorded. Density of interactions was correlated with total space occupation. Flow speed at all sites was logged over 24 h and this factor also correlated with space occupation. Degree of disturbance was assessed through the use of marked boulders at each site. Species diversity peaked where all factors were moderate and was lowest at extreme sites. The effects of these environmental variables and biotic factors in determining community composition are discussed, and a working model detailing a Minimum Stress Inflexion is described. This represents an extension of the intermediate disturbance hypothesis in that it is proposed that disturbance in this system may serve to reduce sediment load as opposed to preventing space monopolisation in the classical model.     

Poly(U)-directed peptide-bond formation from the 2′(3′)-glycyl esters of adenosine derivatives

Summary The self-condensation of 2(3)-O-glycyl esters of adenosine, adenosine-5-(O-methylphosphate) and P₁, P₂-diadenosine-5-pyrophosphate in 6.2 mM solutions at pH 8.0 and -5°C in the presence of 12.5 mM poly(U) yields approximately 3 times as much diketopiperazine as reactions without poly(U). As the concentration of 2(3)-O-(glycyl)-P₁, P₂-diadenosine-5-pyrophosphate is decreased from 6.2 mM to 1.5 mM the yield of diketopiperazine in the presence of poly(U) decreases slightly from 6.6% to 5.2%, whereas, in the absence of poly(U) the yield of diketopiperazine decreases substantially from 2.4% to 0.75%. The enhanced yield of diketopiperazine that is attributed to the template action of poly(U) is temperature dependent and is observed only at temperatures below 10°C (5°C to -5°C) for 6.2 mM 2(3)-O-(glycyl)-adenosine-5-(O-methylphosphate) and below 23°C (15°C to -5°C) for 6.2 mM 2(3)-O-(glycyl)-P₁, P₂-diadenosine-5-pyrophosphate. The absence of a template effect at high temperatures is attributed to the melting of the organized helices. The hydrolysis half-lives at pH 8.0 and -5°C of 2(3)-O-(glycyl)-adenosine, 2(3)-O-(glycyl)-adenosine-5-(O-methylphosphate), 2(3)-O-(glycyl)-P₁, P₂-diadenosine-5-pyrophosphate, and 5-O-(glycyl)-adenosine in the presence of poly(U) are substantially larger than their half-lives in the absence of poly(U). The condensation of 2(3)-O-(glycyl)-adenosine yields 5% of 5-O-(glycyl)-adenosine in the presence of poly(U) compared to 0.7% in the absence of poly(U).Abbreviations DKP diketopiperazine - (gly)₂ glycylglycine - (gly)₃ glycylglycylglycine - AppA-gly 2(3)-O-(glycyl)-P₁, P₂-diadenosine-5-pyrophosphate - MepA-gly 2(3)-O-(glycyl)-adenosine-5-(O-methylphosphate) - Ado-2(3)-gly 2(3)-O-(glycyl)-adenosine - Ado-5-gly 5-O-(glycyl)-adenosine - Boc-gly N-tert-butyloxycarbonylglycine - AppA P₁, P₂-diadenosine-5-pyrophosphate - MepA adenosine-5-(O-methylphosphate) - AppA-Boc-gly 2(3)-O-(Boc-glycyl)-P₁, P₂-diadenosine-5-pyrophosphate - Ado-5-Boc-gly 5-O-(Boc-glycyl)-adenosine - Ado-2(3)-Boc-gly 2(3)-O-(Boc-glycyl)-adenosine     

Cleavage of nucleotides by Ce4+ and the lanthanide metal complexes

The cleavage of adenosine-5-monophosphate (5-AMP) and guanosine-5-monophosphate (5-GMP) by Ce⁴⁺ and lanthanide complex of 2-carboxyethylgermanium sesquioxide (Ge-132) in acidic and near neutral conditions was investigated by NMR , HPLC and measuring the liberated inorganic phosphate at 37°C and 50°C. The results showed that 5-GMP and 5-AMP was converted to guanine (G), 5-monophosphate (depurination of 5-GMP), ribose (depurination and dephosphorylation of 5-GMP), phosphate and adenine (A), 5-monophosphate (depurination of 5-AMP), ribose (depurination and dephosphorylation of 5-AMP), phosphate respectively by Ce⁴⁺. In presence of lanthanide complexes, 5-GMP and 5-AMP were converted to guanosine (Guo) and phosphate and adenosine (Ado) and phosphate respectively. The mechanism of cleaving 5-GMP and 5-AMP is hydrolytic scission