Full 1H NMR assignment of a 24-nucleotide RNA hairpin: Application of the 1H 3D-NOE/2QC experiment

The subject RNA models the binding site for the coat protein of the R17 virus, as well as the ribosome recognition sequence for the R17 replicase gene. With an RNA of this size, overlaps among the sugar protons complicate assignments of the ¹H NMR spectrum. The cross peaks that overlap significantly in 2D-NOE spectra can frequently be resolved by introducing a third, in our approach the double-quantum, frequency axis. In particular the planes in a 3D-NOE/2QC spectrum perpendicular to the 2Q axis are extremely useful, showing a highly informative repeating NOE-2Q pattern. In this experiment substantial J-coupling confers special advantages. This always occurs for geminal pairs (H5/H5 for RNA plus H2/H2 for DNA), as well as for H5/H6, for H3/H4 in sugars with substantial populations of the N-pucker, for H1/H2 for S-puckered sugars, and usually for H2/H3. For the 24-mer RNA hairpin the additional information from the 3D-NOE/2QC spectrum allowed assignment of all of the non-exchangeable protons, eliminating the need for stable-isotope labeling.     

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     

Cyanamide mediated syntheses under plausible primitive earth conditions

Summary When an aqueous solution (pH 7.0) of deoxythymidine 5-phosphate, 4-amino-5-imidazolecarboxamide and cyanamide was dried and heated for 18 h at 60°C, P¹, P²-dideoxythymidine 5-pyrophosphate (I) was formed in a 58% yield. Oligonucleotides were not detected in the reaction product. Under conditions employed in the above reaction, (I) was shown to be stable. In prebiotic polymerization reactions employing deoxythymidine 5-triphosphate as the polymerizing species, (I) could therefore function as a primer and minimize the formation of cyclic nucleotides.Abbreviations dT deoxythymidine - dTMP deoxythymidine 5-phosphate - dTppT P¹, P²-dideoxythymidine 5-pyrophosphate - dTTP deoxythymidine 5-triphosphate - AICA 4-amino-5-imidazolecarboxamide     

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     

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.     

Preparations ofN,N′-ethylene-bridged dipeptides(eXX) constructed from (S)-methionine, -tryptophan, -tyrosine and-N(ɛ)-benzyloxycarbonyllysine through acid-catalyzed cyclization

Summary N, N-Ethylene-bridged bis-(S)-methionine[(2S, 7S)-2, 7-bis(2-methyl-thioethyl)-3,6-diazaoctanedioic acid] derived from (S)-methionine and 1,2-dibromoethane was cyclized and esterified simultaneously in boiling ethanol in the presence of an appropriate amount of strong acid such asp-toluenesulfonic acid, affording a cyclic compound,N, N-ethylene-bridged (S)-methionyl-(S)-methionine ethyl ester {ethyl(2S, 3S)-4-(methylthio)-2-[2-oxo-3-(2-methylthioethyl)-1-piperazinyl] butanoate}, exclusively in 80–90% yields. It was also found that, by applying this method, 70–80% yields of the otherN, N-ethylenebridged dipeptides containing (S)-tryptophan, -tyrosine and -N()-benzyloxycarbonyllysine were obtained.     

Interaction between photosynthetic and respiratory electron-transfer chains in the membranes of Anabaena variabilis

The rate of CO₂- and p-benzoquione-dependent photosynthetic O₂ evolution by Anabaena variabilis cells remained unaltered and the rate of O₂ uptake observed after switching off the light (endogenous respiration) was enhanced by a factor of 6–8 when the O₂ concentration was increased from 200 to 400 M. Photosystem-I-linked O₂ uptake and respiration of the cells incubated with ascorbate and N,N,NN-tetramethyl-p-phenylenediamine was not appreciable influenced by the O₂ concentration. 2-Iodo-6-isopropyl-3-methyl-2,4,4-trinitrodiphenyl ether, blocking electron transfer at the plastoquinone level, suppressed O₂ evolution and had no influence on endogenous respiration. 2-n-Heptyl-4-hydroxyquinoline-N-oxide, an inhibitor of electron transfer between photosystems II and I, as well as the cytochrome-oxidase inhibitors N ₃ ^- , CN^- and NH₂OH, caused a 35–50% retardation of endogenous respiration and blocked photosynthetic O₂ evolution. The molar ratio of cytochromes b₆, f, c-553, aa₃ and photosystem-I reaction centers in the isolated membranes equalled approx. 2:1:2:0.7:2. It is inferred that endogenous respiration of A. variabilis cells is inhibited by the light-induced electron flow through both photosystems at the level of the plastoquinone-plastocyanin-oxidoreductase complex.Abbreviations DCMU 3-(3,4-dichlorophenyl)-1,1-dimethylurea - DNP-INT 2-iodo-6-isopropyl-3-methyl-2,4,4-trinitrodiphenyl ether - Hepes 4-(2-hydroxyethyl)-1-piperazine ethansulfonic acid - TMPD N,N,NN-tetramethyl-p-phenylenediamine     

Determination of internal dynamics of deoxyriboses in the DNA hexamer d(CGTACG)2 by 1H NMR

The conformations and internal dynamics of the deoxyriboses of d(CGTACG)₂ have been determined by NMR measurements at 15°C. The conformations of the sugars were determined using coupling constants and time-dependent NOE measurements. The J-splitting patterns of the H1, H2 and H2 resonances show that the sugars exist as mixtures of conformations near C2 endo (south) and C3 endo (north). The population of the south conformation was larger for the purines than for the pyrimidines. The overall tumbling time of the molecule in ²H₂O was determined from measurements of the cross relaxation rate constant for the H6-H5 vectors of the two cytosine residues. Order parameters were determined for the H1-H2, H2-H2 and H2-H3 vectors from measurements of cross relaxation rate constants, making use of multi-spin analysis of the NOE build up rates. These order parameters are weakly dependent of the base sequence, and except for the terminal Cyt 1 residue, the H2-H2 and H2-H3 vectors are near unity, indicating the absence of rapid pseudorotation on the nanosecond time scale. However, the order parameter for the H1-H2 vector is significantly smaller than expected for rapid pseudorotation indicating the presence of other motions of the sugars. This motion must be about an effective axis parallel to the H2-H vector, and to occur with an angular fluctuation of about 30°.The results show that to obtain highly refined structures for nucleic acids by NMR the effects of spin diffusion and motional averaging cannot be ignored.Some of this work was presented as a poster at the 30^th Experimental NMR Conference at Asilomar, California 1989     

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).     

5′-AMP hydrolysis by suspensions and homogenates of pancreatic islet cells from normal and cortisone-treated rats

Summary Suspensions of endocrine pancreas cells were prepared by shaking collagenase-isolated rat islets of Langerhans in calcium-free buffer. When incubated with 1.0 mM substrate at pH 7.4, the cells split,P _i from 5-AMP at a rate of 87 nmol/h per g DNA, and from-glycerophosphate at a rate of 25 nmol/h per g DNAK _m for 5 AMP was about 54 M. Adenosine or theophylline inhibited the 5-AMP hydrolysis. Homogenization of the cells increased the activity toward 5-AMP by 23% and that toward-glycerophosphate by 115%. Injecting rats with cortisone had no effect on the 5-AMP hydrolysis by whole cells but significantly increased the activity in cell homogenates; the intracellular activity toward 5-AMP was more than doubled by the cortisone treatment. Staining whole islet cells for 5-AMP-splitting activity resulted in a demarcation of the cell periphery in control rats. Cells from cortisone-treated rats showed heavier deposits of reaction product, and their cell periphery did not stand out as clearly. It is suggested that 5-nucleotidase is largely an ectoenzyme in normal rat islet cells. The cells also contain an as yet unidentified intracellular phosphatase that seems to be solely responsible for the increased hydrolysis of 5-AMP in cortisone-treated rats.     

Immobilized Lotus tetragonolobus agglutinin binds oligosaccharides containing the Lex determinant

A defined set of oligosaccharides and glycopeptides containing -linked fucose were used to examine the specificity of the immobilized fucose-binding lectin Lotus tetragonolobus agglutinin (LTA1), also known as lotus lectin. Glycans containing the Lewis x determinant (Lex) Gal1-4[Fuc1-3]GlcNAc1-3-R were significantly retarded in elution from high density LTA-Emphaze columns. The lectin also bound the fucosylated lacdiNAc trisaccharide GalNAc1-4[Fuc1-3]GlcNAc. The lectin did not bind glycans containing either sialylLex or VIM-2 determinants, nor did it bind the isomeric Lea, Gal1-3[Fuc1-4]GlcNAc-R. Although 2-fucosyllactose Fuc1-2Gal1-4Glc) was retarded in elution from the columns, larger glycans containing the H-antigen Fuc1-2Gal1-3(4)GlcNAc-R interacted poorly with immobilized LTA. Our results demonstrate that immobilized LTA is effective in isolating glycans containing the Lex antigen and is useful in analyzing specific fucosylation of glycoconjugates. Abbreviations: LTA, Lotus tetragonolobus agglutinin; UEA-1, Ulex europaeus agglutinin-I; LNT, AAL, Aleuria aurantia agglutinin; Gal1-3GlcNAc1-3Gal1-3Glc; LNnT, Gal1-4GlcNAc1-3Gal1-3Glc; Lex, Lewis x antigen; Lea, Lewis a antigen; GDPFuc, guanosine 5-diphosphate--L-fucose     

The microbial production of 3aα-H-4α- (3′-propionic acid)-5α-hydroxy-7aβ-methylhexahydro-indan-1-one-δ-lactone from cholesterol

Summary A mutant strain of Rhodococcus australis CSIR-236.457 which accumulates 3a-H-4-(3-propionic acid)-5-hydroxy-7a-methylhexahydro-indan-1-one--lactone from cholesterol, stigmasterol and -sitosterol was studied. The product is produced in a 60% molar yield in a dilute black strap molasses medium containing 6–12g/l cholesterol after a 72 hour fermentation period.     

Photoreactive fatty acid analogues that bind to the rat liver fatty-acid binding protein: 11-(5′-azido-salicylamido)-undecanoic acid derivatives

Summary Photoreactive probes for the hydrophobic pocket of the liver fatty acid-binding protein, 11-(5-azido-salicylamido)-undecanoic acid (5 ASU) and its acetyl ester (Ac5 ASU), were synthesized and their interaction with the protein was assessed. Fatty acid-binding proteins are closely related proteins which are abundantly expressed in tissues with active lipid metabolism. A simple model that assumes that the protein possesses a single kind of sites fitted the binding of radioiodinated 5 ASU to L-FABP satisfactorily. The apparent dissociation constant, 1.34×10^–7 M, evidenced a slightly higher affinity than that reported for C16–C20 fatty acids. Consistent with the binding curve, 5 ASU effectively competed with palmitic acid for the hydrophobic sites and the effect was nearly complete for concentrations of 1 gmM; oleic acid, in turn, displaced the radiolabelled probe. Irradiation at 366 nm of¹²⁵I-5 ASU bound to L-FABP caused the covalent cross-linking of the reagent. The amount of radioactivity covalently bound reached a maximum after 2 min thus agreeing with the photo-activation kinetics of the unlabelled compound that evidenced a t_1/2 of 31.1 sec. The yield with which probes bound to L-FABP became covalently linked to the protein, appraised after SDS-PAGE of irradiated samples, was estimated as 23 and 26 per cent for 5 ASU and Ac5 ASU respectively. In turn, irradiation of L-FABP incubated with 5ASU or Ac5 ASU resulted in the irreversible loss of about one fourth its ability to bind palmitic acid. Both results, taken together, suggested that the derivatives are linked to the protein through the sites for fatty acids. When cross-linking of¹²⁵I-5 ASU was performed after incubation with delipidated cytosol and products were analyzed by SDS-PAGE, a band was visualized in a position similar to that of purified L-FABP.Abbreviations FABP Fatty Acid-Binding Protein - L-FABP Hepatic FABP - I-FABP Intestinal FABP - C-FABP Cardiac FABP - 5 ASU-11 (5-azido-salicylamido)-undecanoic acid - Ac5 ASU-11 (O-acetyl-5-azido-salicylamido)-undecanoic acid     

The origin of Q-independent derivatives of phage lambda

Summary qsr (Q-independent) phages are characterised by the replacement of the region of the genome that contains Q, S, R, and the late gene promoter, P_R, with host-derived DNA that codes for functions analogous to those deleted. Restriction endonuclease analysis and DNA/DNA hybridisation methods have been used to show that p4 and qin A 3, two such Q-independent phages, are the product of recombination between and a defective lambdoid prophage (the qsr prophage) located at an as yet unidentified site in the E. coli K 12 chromosome. The qsr prophage is distinct from the defective lambdoid prophage Rac (Kaiser and Murray 1979). In the E. coli K 12 strain AB1157 from which qsr phages cannot be generated, the qsr prophage has suffered an internal deletion. That the qsr prophage appears not to carry a full complement of essential late genes suggests one explanation for its apparently defective nature.     

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     

Ongoing ultradian activity rhythms in the common vole,Microtus arvalis,during deprivations of food,water and rest

Summary The timing mechanism underlying ultradian (2–3 h) activity patterns in the common vole, Microtus arvalis, was studied using behavioural deprivation experiments. These were aimed at distinguishing between a homeostatic control mechanism, in which the rhythmic behaviour itself is part of the causal loop, and a clock mechanism, independent of the behaviour.In 175 experiments, deprivation of food during 3 ultradian cycles in (subjective) daytime did not result in significant changes in the ultradian periodicity of attempts to obtain the food, compared with ad lib. access to food and water. A minor, but significant increase in ultradian activity time () occurred in the course of the deprivation, but this was compensated by a shorter ultradian rest (). These results were obtained both in intact animals (n = 24), which showed ultradian and circadian rhythmicity in behaviour, and in animals (n = 21) with electrolytic lesions aimed at the suprachiasmatic nuclei (SCN), which lacked the circadian modulation of behaviour. Simultaneous deprivation of water and food in 8 voles without circadian rhythmicity during 40 experiments also did not lead to any change in the ultradian periodicity of feeding attempts.Rest deprivation was studied in 5 SCN lesioned voles, by forcing running wheel activity to continue following spontaneous running. Thus, the experimental activity bout was artificially lengthened to 2–9 h in 67 experiments. The onset of the subsequent rest episodes occurred independent of the duration of the preceding . The duration of was dependent on the preceding, experimental in a periodic fashion. The interval experimental (=lengthened +following ) was equal to one, two or three times the control (obtained on nonexperimental days). This result fits the prediction of a clock model and is in conflict with a monotonicincrease of with , as expected in a homeostatic, restorative process.It is concluded that the ultradian timing of activity in the common vole can be explained neither by homeostatic hunger or thirst mechanisms nor by homeostatic rest/activity regulation. The results strongly suggest an independent clock system generating ultradian feeding rhythms in the common vole.Abbreviations DD continuous darkness - LD light-dark regime - LL continuous light - RCA retrochiasmatic area - ARC arcuate nucleus - SCN suprachiasmatic nuclei - ultradian period - ultradian activity time - ultradian rest time     

Abiogenic synthesis of oligonucleotides on kaolinite under the action of ultraviolet radiation

Summary The present work deals with the processes involved in the abiogenic polycondensation of nucleotides adsorbed on the clay mineral kaolinite under the action of ultraviolet (UV) radiation. The dependence of the yield of synthesis products on irradiation dose was studied. The maximum yield corresponds to a 6-h exposure. The newly synthesized substances were analyzed by ion-exchange chromatography. Some fractions were studied for the type of bonds they contained by venom phosphodiesterase and RNase T₂ enzymatic hydrolysis. It was determined that some of the products synthesized by exposure of AMP adsorbed on the surface of clay particles to UV radiation may be looked upon as oligonucleotides in which some fragments have 2–5-bonded and others 3–5-bonded nucleotides     

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     

Cohesive single-stranded ends of Streptomyces temperate bacteriophage R4.

Summary The cohesive single-stranded termini of temperate Streptomyces phage R4 were found to be complementary 11 base single-stranded 3-extended DNAs with the sequence: 5-CGCCGTGTCTT-3 3-GCGGCACAGAA-5     

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