A simple method for the isolation and characterization of thymidylate uptaking mutants in Saccharomyces cerevisiae

Summary The mutant tmp1–10 ^ts which confers thermosensitive auxotrophy for thymidylate is employed for the selection of 5-dTMP uptaking mutants. At the nonpermissive temperature yeast cells phenotypically wild type for thymidylate uptake can grow for only 3 to 4 generations in the presence of 10^–2 M 5-dTMP. Thymidylate utilizing mutants (tum mutants) were isolated which can grow in the presence of 12 to 24 g 5-dTMP/ml. Genetical analysis revealed one of these mutant strains to be a double mutant, tuml tum2. For normal growth haploid thymidylate auxotrophic strains require approximately 360 g 5-dTMP/ml when tum1 and 24 g 5-dTMP when tum2 is present, respectively. Cells prototrophic for thymidylate (TMP) harbouring tum1 tum2 will also take up 5-dTMP and incorporate it specifically into their DNA. Thymidylate utilization in such strains is independent of functional mitochondria, as similar incorporation of labelled 5-dTMP is found in isogenic strains with rho ⁺, rho ^– and rho ⁰ status. Optimal stimulation of the 5-dTMP uptaking principle in haploid TMP strains is found at 4 g 5-dTMP/ml when tum1 and tum2 are present.     

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     

Phagostimulation of the mediterranean fruit fly, Ceratitis capitata by ribonucleotides and related compounds

Females of the medfly, Ceratitis capitata, prefer sucrose solutions containing ribonucleotides to sucrose solutions without them. The order of preference for the nucleotides was: 5GMP>GTP>5CMP>5IMP >dGMP>5UMP>5AMP>5XMP=ATP=2 & 3GMP=RP>3AMP.2AMP, guanosine, inosine, adenine and 5TMP produced no significant stimulation. Females sterilized by irradiation showed reduced attraction to 5GMP as compared to non-irradiated females.Optimal molecular configuration for phagostimulation includes: phosphorylation at the 5 position of the ribose, free hydroxyl groups at 2 and 3 on the ribose, and an NH₂ group at the 2 position of the aromatic ring of purine.It is proposed that the 5GMP in yeast hydrolyzate can be used as a measure of the suitability of the hydrolyzate as a bait.

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Résumé La femelle de la mouche méditerranéenne des fruits, Ceratitis capitata, préfère les solutions de sucrose contenant des ribonucléotides aux simples solutions de sucrose. Lórdre de préférence pour les nucléotides est le suivant: 5GMP>GTP>5CMP>5IMP >dGMP>5UMP>5AMP>5XMP=ATP =2 & 3GMP=RP>3AMP.Le 2AMP, la guanosine, l'inosine, l'adénine et le 5TMP provoquent une stimulation significative. Les femelles montrent aprés stérilisation par irradiation une attirance réduite pour le 5GMP par comparaison avec les femelles non-irradiées.La configuration moléculaire optimale pour la phagostimulation comprend: la phosphorylation en position 5 du ribose; des groupes hydroxyles libres en 2 et 3 sur le ribose; et un groupe NH₂ en position 2 sur le noyau aromatique.Nous proposons que le 5GMP dans l'hydrolysat de levure puisse être utilisé pour mesurer la capacité de l'hydrolysat comme appât.

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Abbreviations 5AMP Adenosine 5-monophosphate - 3AMP Adenosine 3-monophosphate - 2AMP Adenosine 2-monophosphate - dAMP 2-deoxyadenosine 5-monophosphate - ADP Adenosine 5-diphosphate - ATP Adenosine 5-triphosphate - 5GMP Guanosine 5-monophosphate - 2GMP Guanosine 2-monophosphate - 3GMP Guanosine 3-monophosphate - dGMP 2-deoxyguanosine 5-monophosphate - GDP Guanosine 5-diphosphate - GTP Guanosine 5-triphosphate - 5IMP Inosine 5-monophosphate - IDP Inosine 5-diphosphate - ITP Inosine 5-triphosphate - 5XMP Xanthosine 5-monophosphate - 5CMP Cytidine 5-monophosphate - dCMP 2 deoxycytidine 5-monophosphate - CTP Cytidine 5-triphosphate - 5UMP Uridine 5-monophosphate - 5TMP Thymidine 5-monophosphate - RP Ribose 5 monophosphate     

Specific DNA-labelling by exogenous thymidine-5''-monophosphate in Saccharomyces cerevisiae

Summary Strain 211-1aM of Saccharomyces cerevisiae was found to specifically incorporate into its nuclear and mitochondrial DNA exogenous 5-dTMP when it is incubated in a synthetic medium N rich in inorganic phosphate. 3-digestions of DNA from cells labelled with ³²P-5-dTMP revealed that the 5-dTMP molecules pass through cell walls and membranes to the sites of DNA synthesis without being broken down. It is possible in medium N to generate DNA which almost totally derives its thymine-contents from external sources when rather high concentrations of 5-dTMP (approx. 100 g/ml) are offered.     

Species diversities analyzed by density and cover in an early volcanic succession

To evaluate alpha diversities, various variables such as density, cover, volume, and weight have been used. However, density is often a distinct variable from the remaining three. To clarify differences in diversity measured by those two kinds of variables, the data collected in fourteen 2×5 m permanently-marked plots on Mount Usu, Japan, which erupted during 1977 and 1978 in growing seasons from 1983 to 1989 was analyzed, using Shannon's species diversity (H) that is represented as a result of combination of species richness and evenness (J). H and J were evaluated by density (density H and J) and cover (cover H and J). Cover H and J were significantly lower than density H and J, indicating that cover H has different characteristics from density H. Those differences are due to differences in evenness, because species richness is the same. The rank orders of species density are different from those of cover. The predominance of a few perennial herbs greatly decreases cover evenness, while seedling establishment success influences density evenness. Therefore, I propose that, during the early stages of succession on harsh environments such as volcanoes, density diversity represents seedling establishment success rate while cover diversity expresses vegetative reproduction success rate.     

A simple and efficient enzymatic procedure for the deprotection of two base labile chlorinated purine ribosides

Base-labile 6-chloro-2,3,5-tri-O-acetylpurine riboside (1c) and 2-amino-6-chloro-2,3,5-tri-O-acetylpurine riboside (1d) were fully deacetylated through Candida antarctica B lipase hydrolysis, affording respectively 6-chloropurine riboside (2c) and 2-amino-6-chloro-purine riboside (2d). Quantitative results were found at pH 7 and 60 °C in 24 h for 1c and 72 h for 1d. This mild and simple enzymatic technique represents a convenient procedure for the removal of acetyl groups from such base labile halogenated nucleosides.     

Occurrence of pppApp-synthesizing activity in actinomycetes and isolation of purine nucleotide pyrophosphotransferase

The occurrence of adenosine 5-triphosphate-3-diphosphate-synthesizing activity was detected in five strains of actinomycetes; Streptomyces morookaensis, Streptomyces aspergilloides, Streptomyces hachijoensis, Actinomyces violascens and Streptoverticillium septatum, out of 825 strains of actinomycetes, bacteria, fungi and imperfecti. Purine nucleotide pyrophosphotransferase were extracellularly excreted associating with the cell growth, and were purified partially or to apparent homogeniety from the culture filtrate. The enzymes are a monomeric protein with a molecular weight of 18000–26000 and synthesize adenosine, guanosine and inosine 5-phosphate (mono, di or tri)-3-diphosphate such as pApp, ppApp, pppApp, pGpp, ppGpp, pppGpp and pppIpp by transferring a pyrophosphoryl group from the 5-position of ATP, dATP and pppApp to the 3-position of purine nucleotides in the presence of a divalent cation and in alkaline state.Abbreviations pppApp adenosine 5-triphosphate 3-diphosphate - ppApp adenosine 5-diphosphate 3-diphosphate - pApp adenosine 5-monophosphate 3-diphosphate - pppGpp guanosine 5-triphosphate 3-diphosphate     

2′(3′),5′-ADP inhibits initiation-dependent protein synthesis in a cell-free system from Ehrlich ascites tumor cells

When tested in a poly(U)-dependent polyphenylalanine synthesizing system and in a postnuclear supernatant, both derived from Ehrlich ascites tumor cells, 2(3),5-ADP did not affect chain elongation of polypeptide synthesis. In a cell-free system which was dependent on initiation and programmed by natural mRNA, however, the amino acid incorporating activity was suppressed to about 10% of the control in the presence of 1 mM 2(3),5-ADP. The inhibitor was shown not to interfere with the attachment of poly(U) to the small ribosomal subunit and with the formation of mRNA-80S ribosome complexes in a complete protein synthesizing system. The subsequent attachment of a 40S ribosomal subunit to the mRNA-80S ribosome complex and the formation of polysomes, however, was depressed by the inhibitor. The experimental results suggest that 2(3),5-ADP inhibits initiation-dependent protein synthesis between monosome formation and the formation of the first peptide bond(s).     

A 6′ gentamicin acetyltransferase gene allows effective selection of tobacco transformants using kanamycin as a substrate

6 gentamicin acetyltransferases detoxify aminoglycoside antibiotics containing a 6 amino group. We tested whether a 6 gentamicin acetyltransferase gene (6 gat) of Shigella sp. is suitable as selectable gene in plant transformation using kanamycin (Km) as a substrate. A comparative transformation experiment using Nicotiana tabacum SR1 protoplasts showed that 6 gat is as effective for selection of transformants as the commonly used neomycin phosphotransferase II (nptII). In stably transformed plants we detected moderate levels of the 6 gat mRNA. An enzymatic assay was developed with which the acetyltransferase activity of the protein is easily demonstrated.     

Exogenous thymidine 5''-monophosphate as a precursor for DNA synthesis in yeast

Summary Strain MB1015-5C of Saccharomyces cerevisiae can utilize exogenous thymidine 5-monophosphate (5-dTMP) for its DNA synthesis. Studies with either [P³²] or [2-C¹⁴] labelled 5-dTMP reveal first that some of the precursor molecules are taken up intact in DNA synthesis and secondly that 3-digests of highly purified [P³²] DNA yield up to 94% of all [P³²] as 5-dTMP [P³²]. Under the conditions used in these experiments more than 90% of the exogenously supplied 5-dTMP is broken down into orthophosphate and thymidine by an acid phosphatase. Only the orthophosphate is utilized by the yeast cells, mainly for RNA synthesis, and thymidine is not taken up. Suppression of the phosphatase activity is possible by addition of inorganic phosphate to the medium; under these conditions breakdown of 5-dTMP is suppressed but uptake and incorporation of the molecules into the DNA of strain MB1015-5C is still not very effective.     

Carotenoid pigments of Stigmatella aurantiaca (Myxobacterales)

Summary In this first article on the carotenoids of Myxobacterales we report on the minor carotenoids of Stigmatella aurantiaca: phytoene, phytofluene, lycopene, -carotene, 4-keto--carotene, 1,2-dihydro-1-hydroxy--carotene, 4-keto-1,2-dihydro-1-hydroxy--carotene, 4-keto-1,2-dihydro-1-hydroxy-torulene, and 1,2,1,2-tetrahydro-1,1-dihydroxy-lycopene. These pigments account for about 10% of total carotenoids.     

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).     

The effect of the methyl substituent on the bioconversion of cyclohexene derivatives

Summary The absence of the methyl substituent at the 2position of the cyclohexene ring of TCHP enhances the conversion rate as well as the yields of the 3-hydroxy product obtained byStreptomyces natalensis and the 3-keto product obtained byMycobacterium smegmatis.Abbreviations TCHP 1-(2-thienyl)-3-(1-cyclohexen-1-yl)-1-propanone - TCHP-OH 1-(2-thienyl)-3-(3-hydroxyl-1-cyclohexen-1-yl)-1-propanone - TCHP-ketone 1-(2-thienyl)-3-(1-cyclohexen-1-yl-3-one)-1-propane - TMCHP 1-(2-thienyl)-3-(2-methyl-1-cyclohexen-1-yl)-propanone     

Metabolism of a phenylcoumaran substructure lignin model compound in ligninolytic cultures of Phanerochaete chrysosporium

The degradation of the phenylcoumaran substructure model compound methyl dehydrodiconiferyl alcohol by the white-rot wood decay fungus Phanerochaete chrysosporium was investigated using culture conditions optimized for lignin oxidation. Initial attack was in the cinnamyl alcohol side chain, which was oxidized to a glycerol structure. This was subsequently converted by loss of the two terminal carbon atoms, C and C, to yield a C-aldehyde structure, which was further oxidized to the C-acid compound. The next detected intermediate, a phenylcoumarone, was produced by double bond formation between C and C, and oxidation of the C-alcohol to an aldehyde group. Further oxidation of C to an acid yielded the next intermediate. The final identified degradation product was veratric acid. No products from the 5-substituted aromatic ring, and no phenolic products, were found. The initial glycerol-containing intermediate was a mixture of the threo and erythro forms, and no optical activity could be found, suggesting that its formation might have involved nonstereospecific C-C epoxidation followed by non-enzymatic hydrolysis of the epoxide.Abbreviations TLC thin layer chromatography - LDA lithium diisopropyl amide - DDQ 2,3-dichloro-5,6-dicyanobenzoquinone - MS mass spectrometry - UV ultraviolet spectroscopy     

The catalysis of nucleotide polymerization by compounds of divalent lead

Summary Soluble lead salts and a number of lead-containing minerals catalyze the formation of oligonucleotides from nucleoside 5-phosphorimidazolides. The effectiveness of lead compounds correlates strongly with their solubility. Under optimal conditions we were able to obtain 18% of pentamer and higher oligomers from ImpA. Reactions involving ImpU gave smaller yields.Abbreviations A adenosine - U uridine - Im imidazole - MeIm 1-methyl-imidazole - EDTA ethylenediaminetetraacetic acid - pA adenosine 5-phosphate - pU uridine 5-phosphate - Ap adenosine cyclic 2:3-phosphate - ATP adenosine 5-triphosphate - AppA P₁,P₂-diadenosine 5-diphosphate - pNp (N = A,U) nucleotide 2(3), 5-diphosphate - ImpA adenosine 5-phosphoreimidazolide - ImpU uridine 5-phosphorimidazolide - A ²pA adenylyl-[25]-adenosine - A ³pA adenylyl-[35]-adenosine - pA ²pA 5-phospho-adenylyl-[25]-adenosine - pA ³pA 5-phospho-adenylyl-[35]-adenosine - pUpU 5-phospho-uridylyl-uridine - pApU 5-phospho-adenylyl-uridine - pUpA 5-phospho-uridylyladenine - (pA)n (n, 2,3,4,) oligoadenylates with 5 terminal phosphate - ImpApA 5-phosphorimidazolide of adenylyl adenosine - (pA) ₅₊ pentamer and higher oligoadenylates with 5 terminal phosphate - (Ap)nA (n = 2,3,4) oligoadenylates without terminal phosphates In the following we do not specify the nature of the internucleotide linkageIn the following we do not specify the nature of the internucleotide linkage     

Cyclic nucleotide phosphodiesterases of the renal cortex

Summary Cyclic nucleotide phosphodiesterase in the basal-lateral segment of plasma membranes from proximal tubule cells of the rabbit renal cortex was studied and compared to that in the brush border segment of the plasma membrane. Both adenosine 3,5-monophosphate and guanosine 3,5-monophosphate were hydrolyzed by the basal-lateral membrane, but activity varied differently with the two substrates in a complex concentration-dependent manner. Activity with adenosine 3,5-monophosphate was greater than, equal to, or less than with guanosine 3,5-monophosphate, at concentrations of 1000, 100, and 10 to 1 m, respectively. Basal-lateral membrane phosphodiesterase activities at 1 and 500 m substrate exhibited differential responses to pH, metals, heat, and a heat stable inhibitor. Stimulation by guanosine 3,5-monophosphate and inosine 3,5-monophosphate of adenosine 3,5-monophosphate hydrolysis was found in basal-lateral but not in brush border membranes. This stimulation was potentiated by ethyleneglycol-bis(-aminoethyl ether)N,N-tetraacetic acid and ethylenediaminetetraacetate, inhibited by Triton X-100, and totally blocked by Zn²⁺. The findings indicate that multiple forms of phosphodiesterase are present in the basal-lateral segment and these differ from the activities in the brush border region of the plasma membrane. The characteristics of (i) allosteric, guanosine 3,5-monophosphate-sensitivity of adensoine 3,5-monophosphate phosphodiesterase, and (ii) relatively high guanosine 3,5-monophosphate phosphodiesterase activity, in basal-lateral membranes, which are also enriched in adenylate and guanylate cyclase, suggest an important physiological role for these phosphodiesterases in the regulation of net production of cyclic nucleotides in the renal cortex.     

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.     

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     

Labdane diterpene derivatives from Holwaya mucida

Clumps of white crystals present in 40-day-old malt agar cultures of Holwaya mucida were isolated as long white needles by crystallization from ethanol following short extraction with chloroform. The levorotary compound ([] ₂₈₉ ²¹ =-193.8°) was recognized as a -lactone (C₁₇H₂₀O₅) by infrared and mass spectrometry. It was identified as 7-methoxy-3a, 10b-dimethyl-1, 2, 3, 3a, 5a, 7, 10b, 10c-octahydro-4H, 9H-furo[2, 3, 4 : 4, 5]naphtho[2, 1-c]pyran-4, 9-dione, a labdane-derived compound known as antibiotic LL-Z1271. Preparative thin-layer chromatography of the mother liquor afforded 2 minor metabolites. One was identified as LL-Z1271, the demethylated analogue of LL-Z1271. The other one named LL-Z1271, was recognized as a compound related to and : its structure could not be fully elucidated. H. mucida (anamorph: Crinula calciiformis) has no taxonomic relationship with two other LL-Z1271 producing species viz. Acrostalagmus sp. (= Acremonium cf. atrogriseum) and Oidiodendron truncatum.     

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