| | 21 | Author
| M. Suwalsky, M. A. Espinoza, M. Bagnara, C. P. Sotomayor | Requires cookie* | | | Title
| X-Ray and Fluorescence Studies on Phospholipid Bilayers. IX. Interactions with Pentachlorophenol  | | | | Abstract
| Pentachlorophenol (PCP) is a widely used and highly toxic fungicide. Its toxicity is mainly expressed at the cell membrane level. It is, therefore, o f interest to test its ability to alter the lipid bilayer organization. The present study was performed by X-ray diffraction techniques on dimyristoylphosphatidylethanolam ine (D M PE) and dim yristoylphosphatidylcholine (D M P C) bilayers and by fluorescence on DM PC liposomes. These two phospholipids are re spectively found at the inner and outer monolayers o f human erythrocyte membranes. Each type o f phospholipid was made to interact with different concentrations o f the sodium form o f PCP in absence and in presence o f water. It was found that PCP significatively affected the structure o f both phospholipids, being the damage much higher in DM PC bilayers. | | | |
Reference
| Z. Naturforsch. 45c, 265 (1990); received September 18 1989 | | | |
Published
| 1990 | | | |
Keywords
| X -R ay Diffraction, Fluorescence, Phospholipid Bilayers, Pentachlorophenol, Toxicity | | | |
Similar Items
| Find | | | DEBUG INFO
| | | | | TEI-XML for
| default:Reihe_C/45/ZNC-1990-45c-0265.pdf | | | | Identifier
| ZNC-1990-45c-0265 | | | | Volume
| 45 | |
| 22 | Author
| MarcelA K Jansen3, Shmuel Malkinb, Marvin Edelmana | Requires cookie* | | | Title
| Differential Sensitivity of 32 kDa-D 1 Protein Degradation and Photosynthetic Electron Flow to Photosystem II Herbicides | | | | Abstract
| Degradation of the 32 kDa-D 1 protein, a photosystem II reaction centre component, was studied as a function of linear electron flow in visible light in the presence of various photosys tem II herbicides. Under these conditions, herbicide specific effects on protein degradation were clearly evident. 32 kDa-D 1 protein degradation and electron flow between Q a and Q b proved to be only partially correlated. We conclude that inhibition of protein degradation by PS II herbicides in visible light is not simply correlated to displacement of Q b. | | | |
Reference
| Z. Naturforsch. 45c, 408—411 (1990); received December 12 1989 | | | |
Published
| 1990 | | | |
Keywords
| Diuron, Bromoxynil, Dinoseb, Oxygen, Evolution, Chlorophyll, Fluorescence | | | |
Similar Items
| Find | | | DEBUG INFO
| | | | | TEI-XML for
| default:Reihe_C/45/ZNC-1990-45c-0408.pdf | | | | Identifier
| ZNC-1990-45c-0408 | | | | Volume
| 45 | |
| 23 | Author
| Z. Naturforsch | Requires cookie* | | | Title
| Propagation of Voltage Transients in Arborized Neurites of Retzius Cells of the Leech in Culture | | | | Abstract
| Propagation o f electrical signals is studied in Retzius cells o f the leech in culture using volt age-sensitive fluorescent dyes at a spatial resolution o f 8 x 8 (am2 and 1 4 x 1 4 |im 2 and at a sam pling interval o f 0.12 ms. The neurons are stimulated by a microelectrode impaled in the soma. Action potentials o f a halfwidth o f 2 -3 ms are triggered close to the end o f the primary neurite dissociated from the leech. They propagate back to the soma at invariant halfwidth at a veloci ty o f 5 0 -2 3 0 jam/ms. They pervade extended arborized secondary neurites which are grown on extracellular matrix protein. Their width is enhanced up to a factor two. The velocity is around 1 0 0 -150 (im/ms such that delays up to 3.5 ms are observed. Accordingly the neuritic trees are not isopotential. The features o f propagation are found to be incompatible with passive spread. | | | |
Reference
| Z. Naturforsch. 46c, 687—6 (1991); received March 5 1991 | | | |
Published
| 1991 | | | |
Keywords
| Leech, Neuron, Arborization, A ction Potential, Fluorescence | | | |
Similar Items
| Find | | | DEBUG INFO
| | | | | TEI-XML for
| default:Reihe_C/46/ZNC-1991-46c-0687.pdf | | | | Identifier
| ZNC-1991-46c-0687 | | | | Volume
| 46 | |
| 24 | Author
| V. Ictor, B. Curw, G. Ert, S. Chan Sk Er, O. Scar, J. De, V. Os, J. S. Van Rensen | Requires cookie* | | | Title
| Comparison of Photosynthetic Activities in Triazine-Resistant and Susceptible Biotypes of Chenopodium album | | | | Abstract
| Triazine-resistant and susceptible Chenopodium album plants were grown at low and at high light irradiances. A t the lower light irradiance the dry m atter production of the resistant and the susceptible plants were almost similar. At the higher irradiance the resistant biotype had a significantly lower production. Fluorescence studies showed that the photochemical yield and the photosystem II electron transport rate were lower in the resistant biotype. It could be demonstrated in intact leaves that the lower productivity of the resistant biotype is caused by a higher sensitivity to photoinhibition. However, when studying effects of photoinhibition on electron flow and photophosphorylation in isolated thylakoids o f the two biotypes, no signifi cant differences between resistant and susceptible plant materials were observed. It is suggest ed that the difference between resistant and susceptible biotypes connected with processes pro tective against photoinhibition in intact leaves, are lost during the isolation of thylakoids. | | | |
Reference
| Z. Naturforsch. 48c, 278 (1993); received November 26 1992 | | | |
Published
| 1993 | | | |
Keywords
| Chloroplasts, Triazine-Resistance, Photosystem II, Photoinhibition, Fluorescence | | | |
Similar Items
| Find | | | DEBUG INFO
| | | | | TEI-XML for
| default:Reihe_C/48/ZNC-1993-48c-0278.pdf | | | | Identifier
| ZNC-1993-48c-0278 | | | | Volume
| 48 | |
| 25 | Author
| NavassardV. Karapetyanab, Ute Windhövel3 ', AlfredR. Holzwarthc, Peter Bögera | Requires cookie* | | | Title
| Physiological Significance of Overproduced Carotenoids in Transformants of the Cyanobacterium Synechococcus PCC7942 | | | | Abstract
| The functional location of carotenoids in the photosynthetic apparatus of -crtB and -pys transformants of the cyanobacterium Synechococcus PCC7942 was studied and compared with a control strain -pF P l-3. These transformants overproduce carotenoids due to the insertion of an additional foreign phytoene synthase gene. A higher carotenoid content was found for -crtB and -pys transformants both in whole cells and isolated membranes; the -crtB transformant was also enriched with chlorophyll. 77-K fluorescence emission and excita tion spectra of the phycobilin-free membranes were examined for a possible location of overproduced carotenoids in pigment-protein complexes in situ. A similar ratio of the ampli tudes of fluorescence bands at 716 and 695 nm emitted by photosystems I and II, found for the three strains, indicates that the stoichiometry between photosystems of the transformants was not changed. Overproduced carotenoids are not located in the core antenna of photosys tem I, since 77-K fluorescence excitation spectra for photosystem I of isolated membranes from the studied strains do not differ in the region of carotenoid absorption. When illumi nated with light of the same intensity but different quality, absorbed preferentially by either carotenoids, chlorophylls or phycobilins, respectively, oxygen evolution was found always higher in the transformants -crtB and -pys than in -p F P l-3 control cells. Identical kinetics of fluorescence induction of all strains under carotenoid excitation did not reveal a higher activity of photosystem II in cells enriched with carotenoids. It is suggested that overpro duced carotenoids of the transformants are not involved in photosynthetic light-harvesting; rather they may serve to protect the cells and its membranes against photodestruction. | | | |
Reference
| Z. Naturforsch. 54c, 191—198 (1999); received December 18 1998 | | | |
Published
| 1999 | | | |
Keywords
| Carotenoid, Chlorophyll, Cyanobacterium, Fluorescence, Oxygen Evolution | | | |
Similar Items
| Find | | | DEBUG INFO
| | | | | TEI-XML for
| default:Reihe_C/54/ZNC-1999-54c-0191.pdf | | | | Identifier
| ZNC-1999-54c-0191 | | | | Volume
| 54 | |
| 26 | Author
| Zoltán Takács, Zsolt Csintalan, Zoltán Tuba | Requires cookie* | | | Title
| Responses of the Lichen Cladonia convoluta to High C 0 2 Level and Heavy Metal Treatment | | | | Abstract
| Despite of the downward acclimation of photosynthesis in C. convoluta, increased net photosynthesis and carbon balance can be anticipated in response to elevated atmospheric C 0 2 level. C 0 2 exchange measurement seems to be m ore indicative when detecting heavy metal stress than fluorescence parameters. Among these, the relative fluorescence decrease ratio (R F d 690) shows damage first, suggesting that the primary attack site for heavy metal ions is C 0 2 fixation and reaction centres are harmed last. Long-term elevated C 0 2 amelio rates partly this damage by improving C-balance to a greater extent in the heavy-metal stressed lichens. | | | |
Reference
| Z. Naturforsch. 54c, 797—8 (1999); received November 15 1998/M arch 5 1999 | | | |
Published
| 1999 | | | |
Keywords
| Cadmium, Lead, Fluorescence, Respiration, Photosystem II | | | |
Similar Items
| Find | | | DEBUG INFO
| | | | | TEI-XML for
| default:Reihe_C/54/ZNC-1999-54c-0797.pdf | | | | Identifier
| ZNC-1999-54c-0797 | | | | Volume
| 54 | |
| 27 | Author
| I. Timtcheva, P. Nikolov, St Minchevand, N. Sofroniev | Requires cookie* | | | Title
| Luminescence Properties of Some 4-or 5-Aminosubstituted Indan-13-Diones | | | | Abstract
| The photophysical characteristics of some 4(5)-amino-2-aryl-and 4(5)-amino-2-aryl-2-carboxy-methyl-l,3-indandiones have been studied in solvents of different polarity at room temperature and at 77 °K. In contrast to the 2-arylindan-l,3-diones unsubstituted in the phthaloyl fragment, the compounds investigated are photostable and fluoresce in the region 25 000-18 000 cm -1 with fluorescence quantum yields between 0.1 and 0.5. | | | |
Reference
| Z. Naturforsch. 42a, 289—292 (1987); received October 22 1986 | | | |
Published
| 1987 | | | |
Keywords
| 4-and 5-amino indan-l, 3-diones, absorption, fluorescence, phosphorescence | | | |
Similar Items
| Find | | | DEBUG INFO
| | | | | TEI-XML for
| default:Reihe_A/42/ZNA-1987-42a-0289.pdf | | | | Identifier
| ZNA-1987-42a-0289 | | | | Volume
| 42 | |
| 28 | Author
| J. Krzystek, H.J U C Von Schütz, Wolf, R.-D Stigler, J. J. Stezowski | Requires cookie* | | | Title
| Characterization of the Phenanthrene-Tetrachlorophthalic Anhydride (P/TCPA) 1:1 Charge-Transfer Crystal: Spectroscopic and Structural Investigations | | | | Abstract
| The 1:1 phenanthrene-tetrachlorophthalic anhydride (P/TCPA) charge-transfer complex crystalizes with monoclinic symmetry, space group P2,, with two magnetically inequivalent stacks in the unit cell. The noncentrosymmetric space group is very unusual for CT-complexes. The optical emission spectra at low temperature are characterized by a strong CT phospho-rescence and a weak CT fluorescence and delayed fluorescence. The S, band lies at 22 800 ± 100 cm" 1 , the T, band at 21 200 ± 100 cm" 1 . Above 15 K triplet excitons, moving along the stacks are revealed by ESR. They have a CT character of about 30%, coinciding with that of the shallow X-traps found by ODMR at jow temperatures. A further trap, with zero-field-splitting (zfs) parameters of £> = ±0.0617, E = + 0.0116 cm" 1 has a much larger CT character of 50% as found in the isolated complex in low-temperature glass [1]. A structural model is proposed. | | | |
Reference
| Z. Naturforsch. 42a, 622—630 (1987); received February 28 1987 | | | |
Published
| 1987 | | | |
Keywords
| Charge-transfer crystal, crystal structure, fluorescence, phosphorescence, triplet excitons | | | |
Similar Items
| Find | | | DEBUG INFO
| | | | | TEI-XML for
| default:Reihe_A/42/ZNA-1987-42a-0622.pdf | | | | Identifier
| ZNA-1987-42a-0622 | | | | Volume
| 42 | |
| 30 | Author
| StuartM. Ridley, Peter Horton | Requires cookie* | | | Title
| DCMU-Induced Fluorescence Changes and Photodestruction of Pigments Associated with an Inhibition of Photosystem I Cyclic Electron Flow | | | | Abstract
| Diuron (DCM U) induces the photodestruction o f pigm ents, w hich is the initial herbicidal symptom. As a working hypothesis, it is proposed that this sym ptom can only be produced when the herbicide dose is sufficiently high to inhibit not only photosystem II electron transport alm ost completely, but also inhibit (through over oxidation) the natural cyclic electron flow associated with photosystem I as well. Using freshly prepared chloroplasts, studies o f D C M U -induced fluorescence changes, and dose responses for inhibition o f electron transport, have been com pared with a dose response for the photodestruction o f pigm ents in chloroplasts during 24 h illumination. Photodestruction o f pigm ents coincides with the inhibition o f cyclic flow. | | | |
Reference
| Z. Naturforsch. 39c, 351 (1984); received October 10 1983 | | | |
Published
| 1984 | | | |
Keywords
| Diuron (DCM U), Photodestruction, Fluorescence, Photosystem I, Cyclic Electron Flow | | | |
Similar Items
| Find | | | DEBUG INFO
| | | | | TEI-XML for
| default:Reihe_C/39/ZNC-1984-39c-0351.pdf | | | | Identifier
| ZNC-1984-39c-0351 | | | | Volume
| 39 | |
| 31 | Author
| G. Renger, R. H. Agem Ann, W.F J V Erm Aas | Requires cookie* | | | Title
| Studies on the Functional Mechanism of System II Herbicides in Isolated Chloroplasts | | | | Abstract
| The effect o f specific proteolytic enzymes on variable fluorescence, p-benzoquinone-m ediated oxygen evolution, PS II herbicide (atrazine and brom oxynil) binding, and protein degradation has been analyzed in isolated class II pea chloroplasts. It was found that: 1. Trypsin and a lysine-specific protease effectively reduce the m axim um chlorophyll-a flu o rescence yield, whereas the initial fluorescence remains alm ost constant. At the sam e number o f enzymatic activity units both proteases have practically the sam e effect. 2 Trypsin and a lysine-specific protease inhibit the /»-benzoquinone-m ediated flash-induced oxygen evolution with trypsin being markedly more effective at the sam e num ber o f activity units o f both enzymes. Unstacked thylakoids exhibit a higher sensitivity to proteolytic degrada tion by both enzymes. 3. Trypsin and a lysine-specific protease reduce the binding capacity o f [14C]atrazine, but enhance that o f [l4C]bromoxynil (at long incubation tim es trypsin treatm ent also impairs bromoxynil binding). At the same specific activity a m arkedly longer treatm ent is required for the lysine-specific protease in order to achieve the same degree o f m odification as w ith trypsin. 4. Trypsin was found to attack the rapidly-turned-over 32 kD a-protein severely, whereas the lysine-specific protease does not m odify this polypeptide. On the other hand, the lysine-specific protease attacks the light harvesting com plex II. 5. Under our experimental conditions an arginine-specific protease did not affect chlorophyll-a fluorescence yield, /?-benzoquinone-mediated oxygen evolution, herbicide binding and the p oly peptide pattern. Based on these results a m echanism is proposed in w hich an as yet unidentified polypeptide with exposable lysine residues, as well as the lysine-free "Q B-protein" regulate the electron transfer from Q ^ to Q B and are involved in herbicide binding. | | | |
Reference
| Z. Naturforsch. 39c, 362—367 (1984); received Decem ber 1 1983 | | | |
Published
| 1984 | | | |
Keywords
| Chloroplasts, Proteolytic Enzymes, Fluorescence, Oxygen Evolution, H erbicide Binding | | | |
Similar Items
| Find | | | DEBUG INFO
| | | | | TEI-XML for
| default:Reihe_C/39/ZNC-1984-39c-0362.pdf | | | | Identifier
| ZNC-1984-39c-0362 | | | | Volume
| 39 | |
| 33 | Author
| Michael Bender, Ulrich Heber, K. Arl-, Josef Dietz | Requires cookie* | | | Title
| Saline Growth Conditions Favour Supercooling and Increase the Freezing Tolerance of Leaves of Barley and Wheat | | | | Abstract
| When young plants o f barley and wheat grown in hydroponic culture were subjected to salt stress, their freezing tolerance increased with increasing severity o f salt stress. Detached leaves from salt-stressed plants also exhibited an increased ability to supercool. A voidance o f ice for mation permitted leaf survival at subzero temperatures which were no longer tolerated when ice nucleation resulted in extracellular freezing. The increased freezing tolerance under salt stress is attributed to osm otic adjustment o f the plants. Increased cellular solute concentra tions decrease the extent o f cellular dehydration at freezing temperatures, thereby decreasing mechanical and chemical stresses on biomembranes during freezing and thawing. | | | |
Reference
| Z. Naturforsch. 47c, 695—7 (1992); received M ay 14/July 9 1992 | | | |
Published
| 1992 | | | |
Keywords
| Barley, Chlorophyll a, Fluorescence, Freezing Tolerance (Leaves), Salt Stress, Supercooling | | | |
Similar Items
| Find | | | DEBUG INFO
| | | | | TEI-XML for
| default:Reihe_C/47/ZNC-1992-47c-0695.pdf | | | | Identifier
| ZNC-1992-47c-0695 | | | | Volume
| 47 | |
| 34 | Author
| G. Renger, H. M. Gleiter, E. Haag, F. Reifarth | Requires cookie* | | | Title
| Photosystem II: Thermodynamics and Kinetics of Electron Transport from Qa" to Q b(Q b' ) and Deleterious Effects of Copper(II) | | | | Abstract
| Studies on thermodynamics and kinetics o f electron transfer from QA~ to QB(QB") were per formed by m onitoring laser flash induced changes o f the relative fluorescence emission as a function o f temperature (220 K < T < 310 K) in isolated thylakoids and PS II membrane frag ments. In addition, effects o f bivalent metal ions on PS II were investigated by measuring conven tional fluorescence induction curves, oxygen evolution, manganese content and atrazine bind ing mostly in PS II membrane fragments. It was found: a) the normalized level o f the fluores cence remaining 10 s after the actinic flash (FJF0) steeply increases at temperatures below -1 0 to -2 0 °C, b) the fast phase o f the transient fluorescence change becomes markedly retard ed with decreasing temperatures, c) am ong different cations (Cu2+, Zn2+, Cd2+, N i2+, Co2+) only Cu2+ exhibits marked effects in the concentration range below 100 jim and d) Cu2+ decreases the normalized variable fluorescence, inhibits oxygen evolution and diminishes the affinity to atrazine binding without affecting the number o f binding sites. The content o f about four manganeses per functionally competent oxygen evolving complex is not changed by [Cu2+] < 70 |iM. Based on these findings it is concluded: i) a temperature dependent equilibrium between an inactive (I) and active (A) state o f QA~ reoxidation by Q b(Qb) is characterized by standard | | | |
Reference
| Z. Naturforsch. 48c, 234 (1993); received November 23 1992 | | | |
Published
| 1993 | | | |
Keywords
| Photosystem II, Q B-Site, Copper(II) Effects, Fluorescence, Oxygen Evolution | | | |
Similar Items
| Find | | | DEBUG INFO
| | | | | TEI-XML for
| default:Reihe_C/48/ZNC-1993-48c-0234.pdf | | | | Identifier
| ZNC-1993-48c-0234 | | | | Volume
| 48 | |
| 35 | Author
| ShigetohM. Iyachi11, JoachimB. Ürger, K. Iriakos, K. Otzabasisb, JensT. Hielm Annc, H. O. Rst Senger | Requires cookie* | | | Title
| Photosynthetic Characteristics of Three Strains of Cyanobacteria Grown under Low-or High-C02 Conditions | | | | Abstract
| Quantum requirements of photosynthetic oxygen evolution at 679 nm, fluorescence em is sion spectra at liquid nitrogen temperature (77 K) and fluorescence induction kinetics in the presence of DCM U, were measured in the cyanobacteria Anabaena variabilis M3, Anabaena variabilis ATCC 29413 and A nacystis nidulans R2, each grown under low-or high-C02 condi tions. L o w -C 0 2 grown cells o f the cyanobacteria showed a higher quantum requirement of photosynthetic oxygen evolution and a higher ratio o f F7U)_740 to F680_700 fluorescence and a lower variable fluorescence in the presence of D CM U than high-C02 grown cells. These findings indicate a change in excitation energy distribution in favour of photosystem I. The result might be an enhancement in ATP formation caused by cyclic electron flow which in turn provokes dissolved inorganic carbon (D IC) accumulation in these low-C02 grown cells. | | | |
Reference
| Z. Naturforsch. 51c, 40—4 (1996); received August 4/October 6 1995 | | | |
Published
| 1996 | | | |
Keywords
| Quantum Requirement, Fluorescence, Dissolved Inorganic Carbon, Anabaena variabilis, Anacystis nidulans | | | |
Similar Items
| Find | | | DEBUG INFO
| | | | | TEI-XML for
| default:Reihe_C/51/ZNC-1996-51c-0040.pdf | | | | Identifier
| ZNC-1996-51c-0040 | | | | Volume
| 51 | |
| 36 | Author
| SujataR M Ishra, SurendraChandra Sabat | Requires cookie* | | | Title
| Effect of Magnesium and Calcium Ions on the Photoelectron Transport Activity of Low-Salt Suspended Hydrilla verticillata Thylakoids: Possible Sites of Cation Interaction | | | | Abstract
| Stimulatory effect o f divalent cations like calcium (Ca2+) and magnesium (M g2+) was inves tigated on electron transport activity of divalent cation deficient low-salt suspended (LS) thylakoid preparation from a submerged aquatic angiosperm, Hydrilla verticillata. Both the cations stimulated electron transport activity of LS-suspended thylakoids having an intact water oxidation complex. But in hydroxylamine (N H 2OH) -or alkaline Tris -washed thyla koid preparations (with the water oxidation enzyme impaired), only Ca2+ dependent stimula tion of electron transport activity was found. The apparent K m of Ca2+ dependent stimulation of electron flow from H 20 (endogenous) or from artificial electron donor (exogenous) to dichlorophenol indophenol (acceptor) was found to be identical. Calcium supported stimula tion of electron transport activity in N H 2OH -or Tris -washed thylakoids was electron donor selective, i.e., Ca2+ ion was only effective in electron flow with diphenylcarbazide but not with N H 2OH as electron donor to photosystem II. A magnesium effect was observed in thylakoids having an intact water oxidation complex and the ion became unacceptable in N H 2OH -or Tris -washed thylakoids. Indirect experimental evidences have been presented to suggest that Mg2+ interacts with the water oxidation complex, while the Ca2+ interaction is localized betw een Y z and reaction center of photosystem II. | | | |
Reference
| Z. Naturforsch. 53c, 849—8 (1998); received March 16/May 12 1998 | | | |
Published
| 1998 | | | |
Keywords
| Aquatic Angiosperm, Divalent Cation, Electron Transport, Fluorescence, Hydrilla verticillata | | | |
Similar Items
| Find | | | DEBUG INFO
| | | | | TEI-XML for
| default:Reihe_C/53/ZNC-1998-53c-0849.pdf | | | | Identifier
| ZNC-1998-53c-0849 | | | | Volume
| 53 | |
| 38 | Author
| I. Grabchev, I. Moneva, E. Wolarz3, D. Bauman3, S. Stoyanovb | Requires cookie* | | | Title
| Spectral Properties of 3-Benzanthrone Derivative Dyes in Isotropic Solvents, Polymer Film and Liquid Crystal | | | | Abstract
| Some recently synthesized benzanthrone derivatives bearing azomethine and oxy groups at C-3 po sition have been systematically studied. The influence of the substituents and of the environment (iso tropic and anisotropic media) on the absorption and fluorescence of the dyes and their vibronic transi tions is discussed in this paper. | | | |
Reference
| Z. Naturforsch. 56a, 291—296 (2001); received January 24 2001 | | | |
Published
| 2001 | | | |
Keywords
| 3-Benzanthrone Derivatives, Azomethine and Oxy substitutes, Absorption, Fluorescence, Vibronic Structure | | | |
Similar Items
| Find | | | DEBUG INFO
| | | | | TEI-XML for
| default:Reihe_A/56/ZNA-2001-56a-0291.pdf | | | | Identifier
| ZNA-2001-56a-0291 | | | | Volume
| 56 | |
| 39 | Author
| Wanda Wagner, Maria Zaborowska, Wlodzimierz Puzyna, David Shugar | Requires cookie* | | | Title
| Studies on Purine-Pyrimidine Hydrogen Bonded Base Pairing by Means of Absorption and Emission Spectroscopy | | | | Abstract
| Procedures are described for measurement of association constants between potentially com plementary purine and pyrimidine bases by hydrogen bonding in non-aqueous medium by means of absorption and emission spectroscopy. The methods require that one of the two constituents be fluorescent and exhibit a long wavelength absorption band not, or only partially, overlapped by the second constituent. The foregoing has been applied to measurements of the association constants, and other parameters, of hydrogen-bonded complexes of 2-aminopurine with 1-substituted uracil, thymine and barbital in chloroform solution, both in the ground and excited states. It was estab lished that the 1:1 hydrogen-bonded base pairs 2-aminopurine : 1-cyclohexyluracil and 2-amino purine: 1-octylthymine maintain the ground-state equilibrium during the life time of the excited state, whereas for the corresponding pair 2-aminopurine: 1-methylbarbital this equilibrium is per turbed on excitation. The influence of N-alkylation of the 2-aminopurine residue on base-pairing with the pyrimidines has also been examined. The results are compared with those obtained by other methods. The specific advantages of the procedures employed, and their possible applications to studies on the behaviour of fluorescent residues in polynucleotides, are discussed. | | | |
Reference
| (Z. Naturforsch. 29c, 672 [1974]; received August 1 1974) | | | |
Published
| 1974 | | | |
Keywords
| Purines and Pyrimidines, Hydrogen Bonding, Base-pairing, Excited States, Fluorescence | | | |
Similar Items
| Find | | | DEBUG INFO
| | | | | TEI-XML for
| default:Reihe_C/29/ZNC-1974-29c-0672.pdf | | | | Identifier
| ZNC-1974-29c-0672 | | | | Volume
| 29 | |
|
