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     

The structure of the incompatibility factors of Schizophyllum commune: Constitution of the three classes of B factors

Summary The B factors of Schizophyllum commune are of 3 classes: The high recombining class I has 7 alleles and 7 alleles; the low recombining classes are class II with 7 allels and probably 2 alleles and class III with probably 2 (or also 2) alleles and 7 allels. A fourth hypothetical class (-) was not found and either does not exist or is indistinguishable from class III by the tests employed. The and alleles differ from and by either (a) mutations affecting both mating specificity and recombination frequency, or (b) deletions involving most of the B region.The research was supported by a grant from the Atomic Energy Commission of the U.S. No. (30-1)-3875 and was performed at the Biological Laboratories, Harvard University, Cambridge, Mass., U.S.A.     

Measurement of inter-glycosidic 13C-1H coupling constants in a cyclic β(1→2)-glucan by 13C-filtered 2D {1H,1H}ROESY

Summary A method for measuring three-bond ¹³C-¹H scalar coupling constants across glycosidic bonds in a cyclic (12)-glucan icosamer is presented. This oligosaccharide molecule, with its high degree of symmetry, represents a particular challenge for NMR spectroscopy to distinguish inter-residue from intra-residue heteronuclear coupling effects. Chemically equivalent H2 protons in adjacent glucosyl residues are distinguished on the basis of their different through-space, dipolar interactions with the anomeric protons (H1). The strong NOE contact between anomeric (H1) and aglyconic (H2) protons permits the selective observation of the inter-residue heteronuclear couplings ³J_C1H2 and ³J_C2H1 in a natural-abundance ¹³C-₁-half-filtered {¹H,¹H} ROESY experiment.Abbreviations COSY scalar correlated spectroscopy - NOE nuclear Overhauser effect - NOESY NOE spectroscopy - ROESY rotating-frame NOE spectroscopy     

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.     

Effects of midazolam on the contraction and relaxation of segments of thoracic aorta stripped of endothelium and stimulated by adrenaline – experimental study in rabbits

To evaluate the effects of midazolam on the angiokinesis of segments of rabbits' thoracic aorta stripped of endothelium and stimulated by adrenaline.Two groups of aortic rings removed from albinic rabbits anesthetized with thiopental were used (Group I – 6 animals; Group II – 12 animals), stripped of endothelium, studied in an organ chamber, perfused by Krebs-Henseleit solution. The groups were stimulated by adrenaline, recording the maximum contraction and dT/dt at 12, 36, 60 and 120. When the plateau phase was reached, the vessel was washed with perfusion solution, recording relaxation at 2, 4 and 6. When the base values were reached, Group I underwent a new adrenergic stimulus; and Group II was stimulated with midazolam and then with adrenaline, and the same values were recorded. T test was applied as a statistical analysis when two variables were studied. When studying more than two variables the Anova test was used, supplemented by the Tuckey test.Group I did not show any significant difference between the two stimuli. Group II – the midazolam significantly reduced the maximum contraction induced by adrenaline (83.01 ± 4.11%) (p < 0.01). The dT/dt was reduced at 12 (57.06 ± 8.47%), and also at 36 (70.59 ± 5.26%). There was no significance at 60 and 120 (p < 0.01).The relaxation increased significantly at all measurements – at 2-adrenaline 39.31 ± 9.60%; adrenaline/midazolam: 44.06 ± 9.62% (p < 0.05). At 4-adrenaline: 53.08 ± 8.3%; adrenaline/midazolam: 61.68 ± 8.50% (p < 0.01). At 6-adrenaline: 76.26 ± 5.45%; adrenaline/midazolam: 84.20 ± 7.96% (p < 0.01).Midazolam significantly reduced the maximum contraction obtained by the adrenergic stimulus as well as the dT/dt in the initial phases of contraction. The relaxation speed also increased.     

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).     

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.     

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     

Comparison of-nitro versus-amino 4, 4′-substituents of disulfonic stilbenes as chloride channel blockers

We showed previously that the disulfonic stilbene DNDS (4, 4-dinitrostilben-2, 2-disulfonic acid) was a potent blocker of outwardly rectifying chloride channels (ORCC). The studies reported here were designed to quantify the relationship between electron withdrawal by the 4, 4-substituents and blocker potency. Specifically we compared the blocking effects and molecular properties of the symmetrically substituted 4, 4-diaminostilben-2, 2-disulfonic acid (DADS) and the hemi-substituted 4-amino, 4-nitrostilben-2, 2-disulfonic acid (ANDS) with those of DNDS. Blockade was studied using outwardly rectifying colonic chloride channels incorporated into planar lipid bilayers. DADS was 430-fold and ANDS 44-fold less potent than DNDS as blockers of ORCC. Amplitude distribution analysis revealed that all three disulfonic stilbenes act as open channel blockers. Furthermore, this kinetic analysis indicated that the lower potency of DADS and ANDS was due to an increase in off rate. These results support the conclusion that the 4, 4-substituents make an important contribution to blockade by stabilizing the channel-blocker complex. Isopotential electron contour maps illustrated the dramatic shift in charge at the 4, 4-poles of the disulfonic stilbene molecule from electronegative in DNDS to electropositive in DADS as well as the bipolar contour of ANDS. Thus, the greater potency of DNDS results from the symmetric electronegative regions at the 4, 4-poles of the molecule. We hypothesize that the channel protein has two corresponding electropositive areas at the blocker binding site.     

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     

Involvement of cyclic adenosine-3′, 5′-monophosphate in chloronema differentiation in protonema cultures of Funaria hygrometrica

The role of purine and pyrimidine ribosides, nucleotides and substituted xanthines in the differentiation of chloronema filaments in suspension cultures of protonema of the moss Funaria hygrometrica Hedw. has been examined. Cyclic adenosine-3,5-monophosphate (cAMP) and mono-and dibutyryl cAMP evoked the maximum response in wild-type protonema. ADP and ATP also enhanced chloronema differentiation but were less active than cAMP; pyrimidine derivatives were completely inactive. Inhibitors of cyclic-nucleotide phosphodiesterase aminophylline, theophylline and ICI 58, 301 (3-acetamido-6-methyl-8-n-propyl-s-triazolo-(4,3a)-pyrazine)-mimicked the effect of cAMP. A leaky, chloronema-repressed mutant was isolated and in this mutant cAMP was much more active than cyclic guanosine monophosphate and ADP in enhancing chloronema differentiation. These results strongly indicate that cAMP is involved in chloronema differentiation in Funaria, and a hypothesis on growth regulation in protonema cell cultures is proposed.Abbreviations cAMP, cyclic AMP cyclic adenosine-3, 5-monophosphate - cCMP, cGMP, cIMP cyclic cytosine-, guanosine-and inosine-3, 5-monophosphates, respectively - IAA indole-3-acetic acid - ICI 58,301 3-acetamido-6-methyl-8-n-propyl-s-triazolo-(4,3a)-pyrazine     

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     

Nyctohemeral rhythmicity of type II thyroxine 5′-deiodinase activity in the pineal gland but not in the Harderian gland of the Swiss mouse

Type II thyroxine 5-deiodinase (5-D) activity in both pineal and Harderian glands of the Swiss mouse was studied. Pineal 5-D activity exhibited a nyctohemeral profile with a maximal peak value at 05.00 h, which coincides with that for pineal melatonin production. However, no rhythm of 5-D activity in the Harderian gland could be found. In pineal gland, light at night inhibited the nocturnal increase in 5-D activity, while isoproterenol, a -adrenergic agonist, could not stimulate the enzyme. In the Harderian gland, neither darkness, nor light at night, or isoproterenol were capable of modifying basal values of 5-D activity.     

The formation of dipeptides from amino acids and the 2′(3′)-glycyl ester of an adenylate

Summary The yields of dipeptide obtained from the reaction of 0.2M 2(3)-O-(glycyl)-adenosine-5-(O-methylphosphate) and 0.2M amino acid at pH 8.2 ranged from 0.1% to 35.5% for a group of 15 amino acids. The yields of glyser (35.3%), gly-cys (11.8%) and gly-thr (5.4%) were considerably greater than dipeptide yields obtained from any of the other 12 amino acids ( 1.7%). Aminolysis of 0.05M 2(3)-O-(glycyl)-adenosine-5-(O-methylphosphate) by 0.4M serine ethyl ester yielded 53% glycylserine diketopiperazine, via N-(glycyl)-serine ethyl ester as a transient intermediate. The prebiotic significance of these reactions is discussed.Abbreviations MepA adenosine-5-(O-methylphosphate) - MepA-gly 2(3)-O-(glycyl)-adenosine-5-(O-methylphosphate) - DKP diketopiperazine - serOEt serine ethyl ester - gly-serOEt N-(glycyl)-serine ethyl ester - Boc-gly N-tertbutyloxycarbonylglycine - cyclo-(gly-ser-) glycylserine diketo-piperazine - O-gly-ser O-glycylserine - O-(gly)-gly-ser O-(glycyl)-glycylserine - gly-ser N-glycylserine     

Genetic and biochemical studies on flavonoid 3′-hydroxylation in flowers of Petunia hybrida

Summary In flower extracts of defined genotypes of Petunia hybrida, an enzyme activity was demonstrated which catalyses the hydroxylation of naringenin and dihydrokaempferol in the 3-position. Similar to the flavonoid 3-hydroxylases of other plants, the enzyme activity was found to be localized in the microsomal fraction and the reaction required NADPH as cofactor. A strict correlation was found between 3-hydroxylase activity and the gene Ht1, which is known to be involved in the hydroxylation of flavonoids in the 3-position in Petunia. Thus, the introduction of the 3-hydroxyl group is clearly achieved by hydroxylation of C₁₅-intermediates, and the concomitant occurrence of the 3,4-hydroxylated flavonoids quercetin and cyanidin (paeonidin) in the presence of the functional allele Ht1 is due to the action of one specific hydroxylase catalysing the hydroxylation of common precursors for both flavonols and anthocyanins.     

A New Aerobic Gram-Positive Bacterium with a Unique Ability to Degrade ortho- and para-chlorinated Biphenyls

Strain B51 capable of degrading polychlorinated biphenyls (PCB) was isolated from soil contaminated with wastes from the chemical industry. Based on its morphological and chemotaxonomic characteristics, the strain was identified as a Microbacterium sp. Experiments with washed cells showed that strain B51 is able to degrade ortho- and para-substituted mono-, di-, and trichlorinated biphenyls (MCB, DCB, and TCB, respectively). Unlike the known PCB degraders, Microbacterium sp. B51 is able to oxidize the ortho-chlorinated ring of 2,2-DCB and 2,4-DCB and the para-chlorinated ring of 4.4-DCB. The degradation of 2,4-DCB and 4,4-DCB was associated with the accumulation of 4-chlorobenzoic acid (4-CBA) in the medium in amounts comprising 80–90% of the theoretical yield. The strain was able to utilize 2-MCB, 2,2-DCB, and their intermediate 2-CBA and to oxidize the mono(ortho)-chlorinated ring of 2,4,2-TCB and the di(ortho-para)-chlorinated ring of 2,4,4-TCB. A mixed culture of Microbacterium sp. B51 and the 4-CBA-degrading bacterium Arthrobacter sp. H5 was found to grow well on 1 g/l 2,4-DCB as the sole source of carbon and energy.     

A factor-dependent sulfotransferase specific for 3′-phosphoadenosine-5′-phosphosulfate (PAPS) in the Cyanobacterium Synechococcus 6301

A sulfotransferase isolated from the Cyanobacterium Synechococcus 6301 was found to be specific for 3-phosphoadenosine-5-phosphosulfate (PAPS). The molecular weight of this transferase has been estimated on a Sephadex-G-100 column to be about 58,000. The K _m for PAPS was determined to be 20 M. The pH optimum was 8.0. The thiol dithioerythritol was needed for activity; other thiols such as glutathione, cysteine, or mercaptoethanol did not catalyze this reaction. The transferase, however, could not react directly with the thiol. A heat-stable factor was needed in this reaction. This factor was purified by conventional techniques and its molecular weight was determined on a Sephadex-G-50 column to be about 11,500. The factor showed normal Michaelis-Menten behavior toward the PAPS-sulfotransferase. It has been identified as thioredoxin. The tranferase was inhibited by 3-5-ADP and 2–5-ADP; all other adenine-containing nucleotides such as 2-AMP, 3-AMP, 5-AMP, ADP, and c-AMP did not influence this reaction.Abbreviation PAPS 3-phosphoadenosine-5-phosphosulfate     

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     

Measurement of H2'-C2' and H3'-C3' dipolar couplings in RNA molecules

The quality of nucleic acid solution structures can be significantly improved using residual dipolar coupling data. However, many of the one-bond couplings that could be used for this purpose are difficult to measure. Conventional 2D experiments are often unable to reveal one-bond H2-C2 and H3-C3 couplings in large RNA molecules due to spectral overlap. Here we show how to use 3D HCcH-COSY and Relay HCcH-COSY to measure one-bond H2-C2 and H3-C3 couplings which improved the precision of the structures obtained recently for a 42 nucleotide RNA.     

Regioselective alkylation of benzylβ-d-lactoside and its derivatives by stannylation

The preparation of benzyl 2,3,6,2,6-penta-O-benzyl--d-lactoside, which is a key intermediate for chemical synthesis of oligosaccharide components of glycosphingolipids, was achieved by an improved method. The 3-O-p-methoxybenzyl and 3-O-methyl derivatives were prepared from benzyl 2,3,6,2,6-penta-O-benzyl--d-lactoside through stannylation. By using benzyl -d-lactoside as starting material, benzyl 3-O-methyl-, 3-O-benzyl- and 3-O-p-methoxybenzyl--d-lactoside were regioselectively synthesized using the same procedure.