Cyanine dye structural and voltage-induced variations in photo-voltages of bilayer membranes

Summary Flash illumination alters the voltage across bilayer lipid membranes in the presence of certain cyanine dyes. The waveforms of the photo-voltage vary systematically with dye structure and imposed transmembrane voltage. Experimental results are reported for 27 positively charged cyanine dyes, primarily oxazole derivatives, using lecithin/oxidized cholesterol bilayer membranes and 10-mm sodium chloride solutions. Several dyes do not induce any photo-voltages. Examples are 3,3 diethyl 9 ethyl 2,2 oxacarbocyanine iodide, 3,3 diethyl 2 oxa 2 thiacyanine iodide, and 3,3 dimethyl 2,2 indocarbocyanine iodide. Several dyes, when added to one side of the membranes, induce monophasic waveforms. Examples are 3,3 dimethyl 2,2 oxacarbocyanine chloride, and 3,4,3,4 tetramethyl 2,2 oxazalinocarbocyanine iodide. Other dyes induce a photo-voltage only if transmembrane voltages are imposed. These waveforms are biphasic with some dyes (3,3 diethyl 2,2 oxacarbocyanine iodide, for example) and monophasic with other dyes (3,3 dibutyl 2,2 oxacarbocyanine iodide, for example).The photo-voltage waveforms are explained by models that consider the movement of charged dye molecules within the membrane, following optical excitation. The dye movements are probably induced through charge rearrangements in the dye associated with long-lived triplet states, isomerization, or through excimer formation. These results provide information on the location and orientation of the dye molecules within bilayer membranes. The variations which occur in the waveforms with applied voltage indicate that these membranes are fluid in the direction perpendicular to the membrane plane.     

Geometry of the dry-state oligomerization of 2′,3′-cyclic phosphates

Summary Evaporation of a solution of thymidine plus either theexo or theendo diastereomer of uridine cyclic 2,3-O, O-phosphorothioate (U > p(S) in 1,2-diaminoethane hydrochloride buffer gave the 2,5 and 3,5 isomers of (P-thio) uridylylthymidine (Up(S)dT) in a ratio of 1:2 with a combined yield of about 20%. These isomers were re-converted to U > p(S) and dT by a reaction that is known to proceed by an in-line mechanism. Both the 2,5 and 3,5 isomers gave as product the same diastereomer of U > p(S) that had been used originally in their formation. These dry-state prebiotic reactions (Verlander, Lohrmann, and Orgel 1973) are thus shown to be stereospecific, and both the 2,5 and 3,5 internucleotide bonds are formed by an in-line mechanism.Abbreviations DAE 1,2-diaminoethane - HPLC high pressure liquid chromatography - RNase bovine pancreatic ribonuclease A, EC 3.1.4.22 - TEAB triethylammonium bicarbonate - tris tris(hydroxymethyl)aminomethane - UMP(S) uridine monophosphorothioate - U > p uridine cyclic 2,3-phosphate - U > p(S) uridine cyclic 2,3-O, O-phosphorothioate - Up(S)dT (P-thio)uridylylthymidine - U2p(R_p-S)5dT (P-thio)uridylylthymidine with theR configuration at phosphorous, and a 2,5 internucleotide linkage     

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     

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.     

Untersuchungen zum C′3-Polymorphismus (β 1c-Globulin)

Zusammenfassung Serumproben von 1322 Blutspendern aus Hessen, 40 Familien mit 89 Kindern, 20 Mutter-Kind-Kombinationen und 268 Sera einer Bantupopulation aus Portugiesisch Angola wurden mit einer modifizierten Technik der Hochspannungs-Dünnschichtelektrophorese auf Agarosegel hinsichtlich des C3-Polymorphismus untersucht. Die Genfrequenzen für Weiße (C3^S=0.779, C3^F=0.215) und Neger (C3^S=0.95, C3^F=0,048) stimmen gut mit den Werten anderer Autoren überein. Insgesamt ließen sich bei Weißen 9 Phänotypen sicher abgrenzen, bei Negern 3. Familienstudien bestätigten den für die Allele C3^S und C3^F angenommenen Vererbungsmodus (autosomal codominant) ausnahmslos. Die Frage der Lagerungsstabilität des C3 wurde abschließend untersucht.

---

Investigations on C3-polymorphism ( _1c-Globulin)Gene frequencies and family studies in blood donors from Hessen and a Bantu population

Summary Serum samples of 1322 unrelated individuals from Hessen (Germany), 40 families with 89 children, 20 mother-child-combinations and 268 sera of a Bantu population from Angola were examined for C3 polymorphism using a modified technique of high voltage agarose gel electrophoresis. The gene frequencies for Caucasians (C3^S=0.779, C3^F=0.215) and negroes (C3^S=0.95, C^F=0.048) are in good accordance with those obtained by other authors. In total 9 different phenotypes were observed in Caucasians, 3 phenotypes in negroes. Family studies verify the supposed way of inheritance (autosomal codominant for C3^S and C3^F) without exception. Finally the problem of C3-inactivation by storage was investigated.

     

Effect of adenosine monophosphates on the flowering of Impatients balsamina L., a qualitative short-day plant

Summary Adenosine monophosphates (AMPs) cause the induction of floral buds in Impatients balsamina L. under strictly non-inductive photoperiods and hasten it under inductive photoperiods, cyclic AMP being more effective than 3- or 5-AMPs in this regard.Abbreviations cyclic AMP cyclic 3,5-adenosine monophosphate     

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.     

Topo-optische Färbung der Erythrocytenmembran mit Thiazin- und Chinolinfarbstoffen

Zusammenfassung Die Untersuchungen erwiesen, daß die Farbstoffe 1:9-Dimethyl-Methylenblau, Azur A und N,N-Diäthylpseudoisozyaninchlorid für topo-optische Reaktionen an der Membran von Erythrocyten geeignet sind. Die Farbstoffmoleküle werden an der Membran orientiert gebunden. Ihre Bindung kann durch Behandlung mit Präzipitationslösungen stabilisiert werden, und zugleich wird die Anisotropie verstärkt. Die optische Analyse ergab, daß 1:9-Dimethyl-Methylenblau und Azur A radiär zur Membran ausgerichtet sind, während sich N,N-Diäthylpseudoisozyaninchlorid membranparallel anlagert.

---

Tope-optical staining with thiazin and quinolin dyestuffs of the erythrocyte membrane

Summary The present studies prove the dyestuffs 1.9-dimethyl methyleneblue, azure A and N,N-diethylpseudoisocyanine chloride suitable for topo-optical reactions with the membrane of the red blood cell. The dye molecules are bound in orientated fashion. Treatment with precipitants stabilizes the binding of dye molecules and, in addition, it enhances the birefringence. Optical analysis revealed 1.9-dimethyl methyleneblue and azure A bound in radial position, however, N,N-diethylpseudoisocyanine chloride was bound parallel to the membrane's plane.

     

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.     

The formation of peptides from the 2′(3′)-glycyl ester of a nucleotide

Summary We have synthesized 2(3)-O-(glycyl)-adenosine-5-(O-methylphos-phate), an analogue of the 3-terminus of aminoacylated tRNA. A 0.4M solution of this compound maintained at pH 8.2, yields 5.5% of diglycine and 11.5% of diketopiperazine, in addition to the hydrolysis products glycine and adenosine-5-(O-methylphosphate). Under the same conditions, glycine ethyl ester reacts much more slowly, but ultimately gives similar yields of diglycine and diketopiperazine.The aminolysis of 2(3)-O-(glycyl)-adenosine-5-(O-methylphosphate) by free glycine is relatively inefficient, but serine reacts 20 times more rapidly and yields up to 50% of N-glycylserine. The prebiotic significance of these reactions is discussed.Abbreviations MepA adenosine-5-(O-methylphosphate) - MepA-gly 2(3)-O-(glycyl)-adenosine-5-(O-methylphosphate) - MepA-bis-gly 2,3-O-(bis-glycyl)-adenosine-5-(O-methylphosphate) - DKP diketopiperazine - gly Et glycine ethyl ester - gly-ser N-glycylserine - O-gly-ser O-glycylserine - O-(gly)-gly-ser O-(glycyl)-glycylserine - Boc-gly N-tert-butyloxycarbonylglycine - MepA-Boc-gly 2(3)-O-(Boc-glycyl)-adenosine-5-(O-methylphosphate) - MepA-bis-Boc-gly 2,3-O-(bis-Boc-glycyl)-adenosine-5(O-methylphosphate) - (gly)₂ diglycine - (gly)₃ triglycine     

Prebiotic Formation of ADP and ATP from AMP,Calcium Phosphates and Cyanate in Aqueous Solution

Adenosine-5-triphosphate was synthesized by the phosphorylation of adenosine-5-diphosphate in aqueous solution containing cyanate as a condensing reagent and insoluble calcium phosphate produced from phosphate and calcium chloride. In a similar manner, adenosine-5-diphosphate was synthesized from adenosine-5-monophosphate. When the experiment was carried out in the conditions of 4 °C and pH 5.75, the formation of adenosine-5-diphosphate and adenosine-5-triphosphate from adenosine-5-monophosphate was observed in the yields of 19 and 7%, respectively. The other nucleoside-5-triphosphates were also produced from their respective diphosphates.     

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     

Integration of biochemical functions of different cells of RAT gastric mucosa for hydrochloric acid secretion

Summary The regulation patterns of gastric acid secretion in rats were investigated. Pentagastrin and histamine stimulate gastric acid secretion, but the inhibitors of DNA-dependent synthesis of RNA and of proteins prevent only the pentagastrin action. It has been found that pentagastrin induces histidine decarboxylase in gastric mucosa, ensuring local accumulation of histamine. The latter activates adenylate cyclase and results in 3,5-AMP accumulation in gastric tissues. The administration of pentagastrin, histamine or 3,5-AMP enhances the activity of gastric carbonic anhydrase, the enzyme which takes part in HCI formation. The data suggest that these three compounds act sequentially (pentagastrin histamine 3,5-AMP) and the effect of the last one could be mediated through 3,5-AMP dependent protein kinase. The experiments in vitro demonstrated that gastric carbonic anhydrase can be separated into two isoenzymes and the phosphorylation of one of them by the 3,5-AMP dependent protein kinase sharply increases its activity. The findings raise the possibility that histamine and 3,5-AMP, mediating gastrin action, form together with enzymes (histidine decarboxylase, adenylate cyclase, protein kinase, carbonic anhydrase) a cascade of amplifiers.Autoradiographic studies have shown that [³H]-pentagastrin is not bound by oxyntic cells but adheres preferentially to histamine-producing-like endocrine cells and to the chief cells, while³H-histamine adheres preferentially to oxyntic and to chief cells. Electron microscopy indicates that only pentagastrin (but not histamine) initiates in-like endocrine cells ultrastructural changes characteristic for induction. Pentagastrin, histamine and 3,5-AMP administration produces in oxyntic cells ultrastructural changes typical for the secretion processes.These results lead to assumption that pentagastrin (gastrin) induces histidine decarboxylase in-like endocrine cells of gastric glands. Histamine which is secreted enhances adenylate cyclase activity in the neighbouring oxyntic cells where 3,5-AMP dependent protein kinase activates carbonic anhydrase by means of phosphorylation. These different cells form, probably, a multicellular functional unit for gastric acid secretion.An invited article.     

Formation of nucleoside 5′-polyphosphates under potentially prebiological conditions

Summary Aqueous solutions of linear inorganic polyphosphates incubated in presence of Mg ions depolymerize to give trimetaphosphate. The presence of a nucleoside 5-phosphate has little influence upon the reaction. Drying the products obtained by incubating a linear polyphosphate with Mg ions in the presence of a nucleoside 5-phosphate yields nucleoside 5-polyphos-phates. The prebiological relevance of the reactions is discussed.Abbreviations P_n(n=1,2,3,) linear polyphosphate containing n phosphate residues - P₃! trimetaphosphate - A adenosine - p_nN nucleoside 5-polyphosphate containing n phosphate residues, e.g. with N = A, n = 4 - p₄N adenosine 5-tetraphosphate - _P ^* _lp_mA p_nA, (n = 1 + m); adenosine 5-polyphosphate containing n phosphate units with³³p-label on terminal 1 phosphate groups     

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.     

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     

Rapid plant regeneration of pea using thidiazuron

A simple and rapid pea regeneration procedure was developed. An average of up to 20 shoots formed from hypocotyl explants of cvs. Sugar Ann and Patriot cultured on Murashige and Skoog basal medium supplemented with 0.5 or 1.0 M thidiazuron (N-phenyl-N-1,2,3-thiadiazol-5-ylurea). Hypocotyls of Puget and Sugar Daddy did not respond. Regenerated shoots rooted rapidly when cultured on Murashige and Skoog basal medium containing either 2.0 M -naphthaleneacetic acid or 1.0–2.0 M indole-3-butyric acid. Seeds were harvested from regenerated plants after only 9–11 weeks.Abbreviations BAP 6-benzyladenine - 2,4-d 2,4-dichlorophenoxy acetic acid - GA₃ gibberellic acid - IBA indole-3-butyric acid - MS Murashige and Skoog (1962) medium - NAA -naphthaleneacetic acid - TDZ thidiazuron (N-phenyl-N-1,2,3-thiadiazol-5-ylurea)     

Zur Eignung weiterer Thiazin- bzw. Chinolinfarbstoffe für die topo-optische Reaktion am Plasmalemm

Zusammenfassung Die hier durchgeführten Untersuchungen erwiesen, daß die Thiazinfarbstoffe Azur B, Azur C und Thionin sowie der Chinolinfarbstoff Pinacyanol bzw. sein Hydrochlorid für die topooptische Reaktion am Plasmalemm geeignent sind.-Die an der Membranoberfläche orientiert gebundenen Farbstoffmoleküle werden durch eine nachträgliche Präzipitation stabilisiert und gleichzeitig wird der anisotrope Effekt verstärkt.-Die Thiazinfarbstoffmoleküle (Azur B, Azur C, Thionin) sind nach der optischen Analyse radiär zur Membran ausgerichtet.-Gegenüber dem früher untersuchten Chinolinfarbstoff N,N-Diäthylpseudoisocyaninchlorid, dessen Farbstoffmoleküle parallel zur Membran lagen, sind das Pinacyanol bzw. sein Hydrochlorid in gleicher Weise, wie die Thiazinfarbstoffe radiär zur Membran ausgerichtet.

---

The suitability of further thiazin and quinolin dyes for topo-optical reactions on the plasmalemma

Summary The present studies prove that the thiazin dyes, azure B, azure C and thionin, and the quinolin dyes pinacyanol and its hydrochloride, are suitable for topo-optical staining of the plasmalemma. On the membrane surface the orientated bound dye molecules become stabilized, and with subsequent precipitation the anisotropic effect is reinforced. On optical analysis, the thiazin dye molecules (azure B, azure C and Thionin) are bound radially on the membrane. The molecules of the previously studied quinolin dye, N,N-diethylpseudoisocyanide chloride are bound parallel to the membrane, while pinacyanol and its hydrochloride, like the thiazin dyes, are bound in the radial position.

     

Two-dimensional 1H NMR study of two cyclobutane type photodimers of thymidylyl-(3′→5′)-thymidine

2D NMR spectroscopy and J coupling constant analysis are applied to resolve the structure of two photoproducts of thymidylyl-(35)-thymidine. These products are cyclobutane type thymine dimers possessing the cis-syn (the predominant one) and trans-syn geometry. The cis-syn is formed in an ANTI-ANTI conformation about the N-glycosyl linkages and resembles the normal base-stacked configuration. The glycosidic conformation in solution of the 5 terminal fragment differs from the crystal in which the less common SYN conformation is observed. In this isomer only the sugar pucker of the 3 terminal fragment is changed substantially with respect to the dinucleotide. The trans-syn isomer is formed in a SYN-ANTI glycosidic conformation. In this isomer the sugar puckers of both deoxyribose rings are affected and a preference for a pure 2-endo conformation is observed.Abbreviations dTpdT 2-deoxythymidylyl-(35)-2-deoxythymidine - dTp[]dT cyclobutane type photodimers of dTpdT - dTp- and dTp[]- their 5' terminal fragments (fragment A) - -pdT and-[]pdT their 3 terminal fragments (fragment B) - RP-HPLC reversed-phase high-performance liquid chromatography - COSY two-dimensional correlated spectroscopy - 2D NOE two-dimensional nuclear Overhauser spectroscopy     

Chemoenzymatic galactosialylation with integrated cofactor regeneration

As a precursor for the chemical synthesis of sialylated oligosaccharides, the trisaccharide glycoside Neu5Ac (2-8)Gal(1-4)GlcNAc(1-O)-pent-4-ene was synthesized starting from GlcNAc(1-O)-pent-4-ene, UDP-glucose andN-acetylneuraminic acid in a one pot reaction employing galactosyltransferase and (2-6)sialyl-transferase in a complete cofactor regeneration system.Abbreviations Neu5Ac N-acetylneuraminic acid - CMP-Neu5Ac cytidine 5-monophosphosialate - CMP cytidine 5-monophosphate - CDP cytidine 5-diphosphate - CTP cytidine 5-triphosphate - Gal galactose - GlcNAc N-acetylglucosamine - UDP uridine 5-diphosphate - UDP-Glc uridine-5-diphosphoglucose - UDP-Gal uridine-5-diphosphogalactose - PEP phosphoenolpyruvate