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After lysis of Pseudomonas testosteroni with lysozyme and non-ionic detergents different DNA-protein complexes can be separated in 5 -25% (w/v) neutral sucrose gradient. The protein to DNA ratio of these complexes varies between 0.5-4.5 to 1, whereby the faster sedimenting forms contain more protein than the slower sedimenting ones. Different initial rates of DNase digestion may indicate various degrees of DNA packing in these complexes. The chromosomal complexes of Pseudomonas testosteroni are relatively stable towards pronase. Treatment with RNase or sodium dodecylsulphate is accompanied by a dramatic increase in viscosity and decrease in relative density. It suggests that DNA in these complexes is maintained in its supercoiled form by RNA molecule (s) in a similar way as in isolated chromosome of E. coli.
Chromosomale Strukturen von Pseudomonas testosteroni. II. Aktivität der endogenen RNA-Polymerase
(1976)
After careful lysis the nucleoid of Pseudomonas testosteroni can be isolated in three different forms with compact and unfolded DNA structures 1. The released nucleoids contain endogenous DNA-dependent RNA-polymerase activity using the chromosomal DNA as a template. RNA syn thesis is proportional to duration of RNA-polymerase reaction and amount of DNA-protein-complexes. The sensitivity towards ionic strength and rifampicin indicates that a part of RNA-polymerase activity is tightly bound to the chromosomal DNA.
A screening procedure is presented which allows the isolation of yeast mutants (typ tlr) with highly efficient utilization of exogenous deoxythymidine-5′-monophosphate (5′-dTMP) (>50% ). Data are given concerning the phenomenon of 5′-dTMP utilization in general: (i) The ability of S. cerevisiae to incorporate exogenous 5′-dTMP was found to already be a wild type feature of this yeast, i. e. apparently not to be due to any mutation such as typ , tup, tmp per or tum. Consequently these mutations are interpreted as amplifiers of a pre-given wild type potency. So far eight stages of 5′-dTMP utilization were detected as classified by the optimal 5′-dTMP requirement, with 5′-dTMP biosynthesis blocked, of the corresponding mutant strains isolated. All of them fit well into a mathematical series of the type “2n × 1.5” (n = 0, 1, 2, … , 11), where the product term for n = 11 represents the 5′-dTMP requirement (μg/ml) of the best 5′-dTMP utilizing wild type strain found, (ii) Amplification of the 5′-dTMP utilizing potency obviously is due to any genetically determined alteration of the yeast 5′-dTMP uptaking principle itself or of physiological processes accompanying the monophosphate’s uptake, (iii) The functioning of 5′-dTMP uptake requires acidic (≦ pH 6) conditions in the yeast cell’s outer environment, (iv) Some yeast typ and typ tlr mutants were found to exhibit a more or less pronounced sensitivity towards exogenously offered 5′dTM P. The response of a sensitive strain towards inhibitory concentrations of the nucleotide apparently is co-conditioned by the presence or absence of thymidylate biosynthesis. With 5′-dTMP biosynthesis blocked the 5′-dTMP mediated inhibition is a permanent one and finally leads to the death of a cell. With a functioning thymidylate biosynthesis, in contrast, the inhibition is only temporary, (v) Yeast typ or typ tlr strains were observed to dephosphorylate exogenous 5′-dTMP to thymidine due to a phosphatase activity which cannot be eliminated at pH 7 + 70 mм inorganic phosphate conditions in the growth medium. This 5′-dTMP cleavage obviously occurs outside the cell and does not seem to be correlated both to the monophosphate’s uptake and to the phenomenon of 5′-dTMP sensitivity. The destruction of 5′-dTMP does not disturb (5′-dTMP) DNA-specific labelling.
The kinetics of the photodynamic desactivation of lysozyme in presence of acridine orange as the sensitizer have been investigated in detail varying oxygen, protein, dye concentration, ionic strength and pH value. The kinetics can be approximately described as an over all pseudo-first- order rate process. Changing the solvent from water to D2O or by quenching experiments in presence of azide ions it could be shown that the desactivation of lysozyme is caused exclusively by singlet oxygen. The excited oxygen occurs via the triplet state of the dye with a rate constant considerably lower than that to be expected for a diffusionally controlled reaction. Singlet oxygen reacts chemically (desactivation, k=2.9 × 107 ᴍ-1 sec-1) and physically (quenching process, k = 4.1 × 108 ᴍ-1sec-1) with the enzyme. The kinetical analysis shows that additional chemical reactions between singlet oxygen and lysozyme would have only little influence on the kinetics of the desactivation as long as their products would be enzymatically active and their kinetical constants would be less than about 1 × 108 ᴍ-1 sec-1.
The photodynamic deactivation of lysozyme in presence of acridine orange is caused by a reaction between singlet oxygen formed via the dye triplet state and the protein. In order to identify the region where the singlet oxygen reacts with the protein we have investigated the kinetics of the deactivation in presence ofthe inhibitor of the enzymatic reaction N-acetylglucosamine (GlcNAc). The overall experimental rate constant becomes slower with increasing saccharide concentrations. As we can exclude experimentally that this kinetical effect is caused in presence of the saccharide by a physical quenching of singlet oxygen or of the dye triplet state it has to be assumed that GlcNAc protects the surrounding of its bindings place at subsite C of the enzymatic center sterically against an attack of singlet oxygen. In this region three tryptophan residues are located, which could be sensitive against singlet oxygen. Surprisingly, however, it has been found that only those species are protected, in which a second saccharide molecule is bound to the protein, probably at subsite E at the enzymatic center, where no sensitive amino acid side chains are located.
Antiserum against crystallized 20β-hydroxysteroid dehydrogenase from Streptomyces hydrogenans was used for different immunodiffusion and immunoprecipitation tests to quantify the bacterial enzyme in cell-free supernatants of the microorganism. After immunoprecipitation and gel electrophoresis the molecular weight of the subunits of 20β-hydroxysteroid dehydrogenase was calculated to be 27 300 ± 700.
Levels of the purine nucleoside triphosphates are de creasing towards the end of log phase growth of Streptomyces hydrogenans. Induction of 20β-hydroxysteroid dehy-drogenase by addition of 11β,21-dihydroxy-4,17 (20) -pregna-dien-3-one to the growth medium leads to a pronounced drop in purine nucleoside triphosphate levels with is irreversible in contrast to the initial loss and later accumulation of RNA.
The blue-green alga Anacystis nidulans (strain L 1402-1) was grown at + 37 °C in air (0.03 vol.% CO2 and in air enriched with 3.0 vol.% CO2. The effects of several inhibitors on the activity of aminotransferases, 14CO2 fixation and radioactive photosynthetic products of Anacystis were studied. No serine-pyruvate aminotransferase activity could be found in 10-2 м isonicotinyl hydrazide (INH) ; under the influence of this inhibitor aspartate and alanine aminotransferase were decreased about 49% respectively 17.6%. Serine-pyruvate and alanine aminotransferase activity decreased to more than 50% in 10-3 м glyoxalbisulfite. The obtained inhibitory effect of 10-4 м HPMS on serine-piruvate aminotransferase (35%) was stronger than on the other aminotransferases. DCMU (5 × 10-6 м) inhibition on alanine aminotransferase activity was 83.7%. Under the influence of 10-3 м glyoxalbisulfite no 14C-labelled amino acids could be detected after 5 min photosynthesis; 14C-labelling of phosphoenolpyruvate, malate, phosphoglycolate and glycolic acid increased. Isonicotinyl hydrazide (10-2 м) caused in comparison to the control experiment a lower radioactivity in aspartate, glutamate and phosphoenolpyruvate. The results are discussed with reference to the operation of the glycolate pathway and a carboxylation reaction of phosphoenolpyruvate in the blue-green alga Anacystis nidulans.
The hypothesis of GLIKMAN and ZABRODA (Biochemistry [USSR] 84,, 239 [1969]) that the primary electron donor during photoreduction of manganese(III) in Mn(III)-hydroxychlorin compounds in oxygen free aqueous alkaline solutions is the axially bound OH- ion was tested with Mn(III)-2-a-hydroxyethyl-isochlorin e4. It has been shown that
1) the primary generation of OH radicals upon irradiation of the complex is highly improbable,
2) light is not essential for the reduction reaction,
3) the kinetics of photoreduction of the Mn(III)-compound in 2 N NaOH clearly is not compatible with OH radical formation.
The He I photoelectron spectra of certain MeEHal2 and Me2EHal compounds (E = (N), P, As, Sb; Hal = (F), Cl, Br, J; Me = CH3) are interpreted in terms of a “composite molecule” approach derived for C3vCs systems. Although an “internal standard” is missing here, substituent group-orbitals (nHal, C—H) may be classified with respect to their orientations in space (R, V, T). Ionisation energies are assigned according to this assumption.
PE data of the isoelectronic EMe3/EHal3 compounds and of related molecules (Me2EH, MePH2, CF3PBr2) as well as EHMO calculations with partial inclusion of spin orbit coupling are used to confirm the assignments given for Me2EHal/MeEHal2 series.
Correlations between PE ionisation energies (e.g. nE (IE)) and molecular or atomic properties are critically revised and discussed.
The photoelectron spectrum of H5C6-Te-CH3 displays in its low energy region overlapping bands of gas-phase conformers. Depending on the dihedral angle between the plane of the phenyl ring and the tellurium lone pair, the π conjugation amounts to only 0.1 eV and 0.3 eV, respectively. These values are compared to the considerably larger ones found for the analogous phenyl derivatives H5C6-X-CH3 with X = O, S and Se.
The He I photoelectron spectra of the series RnP(CN)3-n (R = Me, CF3; n = 0, 1, 2, 3) and of Me2ECN (E = N, P, As) are interpreted. The PE assignments are based on the comparison with the PE data of analogous halogeno and hydrogen derivatives as well as related cyano compounds and on simple MO considerations (composite molecule-approach). Hyperconjugative and inductive effects of the substituents CN, Me, F, Cl, and especially CF3 are assessed. The various effects of changing substituents or central atoms within the series are used to confirm the interpretation. The differing electronic structures of halogeno and cyano (pseudohalogeno) compounds are discussed on the basis of their PE spectra.
The well-resolved helium(I) photoelectron spectrum of H3C-Se—Se-CH3 exhibits distinct bands corresponding to 11 of the total 13 valence electron ionizations. The unequivocal assignment is supported by EHMO calculations including spin/orbit coupling. The two selenium lone pair ionizations differ by 0.23 eV; a split observed also for dimethyl disulfide and discussed within a general model for interactions between adjacent lone pairs.
Two routes for the preparation of (CH3)2SnS2N2 are given, which are kinetically controlled reactions. The molecule (CH3)2SnS2N2 was characterized by X-ray analysis. It is an interesting starting material for the preparation of S2N2CO and S3N2O. The latter reacts with iminosulfur oxides and isocyanates under the formation of S3N3SO2F and S3N3SO2CF3. The structure of S3N3SO2F was established by X-ray analysis. The bonding properties are discussed.
The cleavage of thin-nitrogen derivatives with S3N2Cl2 yields also five membered sulfurnitrogen rings. The structure and properties of P3N3F5NS3N2 and C3N3F2NS3N2 are reported. Six, eight and ten membered rings are formed by the reactions of (CH3)3Si–N = S = N–Si (CH3)3 with FSO2–N=S=O, these are S4N4O2 and S5N5+S3N3O4, respectively. The cation S5N5+ is a planar molecule, while the oxygen containing species are puckered. In S4N4O2 the oxygens are attached to one sulfur atom, which has a tetrahedral configuration.
The structure of the silicon containing cyclic and bicyclic rings (CH3)2Si(NSN)2Si(CH3)2 and CH3Si(NSN)3SiCH3 were determined.
The cis-trans-isomerism of the WITTIG hydrocarbon was investigated in solid state and solution by means of fluorescence spectroscopy. The fluorescence behavior of both isomers in 2-methyltetrahydrofurane was determined as a function of concentration, temperature, and wavelength of exciting radiation. Furthermore, irradiation experiments were undertaken with light of various wavelengths.
The results obtained are in agreement with the assumption that the WITTIG hydrocarbon behaves with regard to the cis-trans-isomerism like a 1,3-butadien derivative, i.e. a thermal but no photochemical cis-trans-isomerisation can be detected. The enthalpy difference between the two isomers was estimated to ΔΗ = 250 ± 50 cal/mole. It could be shown that the fluorescence of the cis-isomer is quenched by the trans-isomer. This quenching occurs probably according to the resonance energy transfer mechanism.
1 reacts with SCl2 to yield 2. The methylsilane derivatives [OC–NCH3–CO–NCH3-SO2–N]nSi(CH3)4-n for n = 2, 3 and 4 are readily prepared from 1 and (CH3)2SiCl2, CH3SiCl3 and SiCl4. The IR and mass spectra are reported.
Li6UO6 has a reversible phase transformation at 680°C and decomposes above about 850°C. At high pressure the low temperature modification becomes unstable because of an invariant point in the system Li2O—Li4UO5 at approximately 13 Kb and 620°C. β-Li6UO6 has a triclinic unit cell with a = 5.203, b= 5.520, c = 5.536 Å, α = 114.7, β = 120.7 and γ = 75.5°. The close relationship between the crystal structures of Li6TeO6 and Li6UO6 is also suggested from similar infrared spectra and from partial solid solution Li6UO6—Li6TeO6.
Nuclear magnetic resonance measurements were carried out on neutron activated 20F(T1/2=11s) nuclei in a single crystal of KZnF3. The quadrupolar splitted NMR spectrum, detected via the 20F β-radiation asymmetry, could be observed using a radio frequency modulation technique. The quadrupole coupling constant was determined to e2 q Q/h= + (12.0 ± 1.5) MHz at room temperature. The sign of e2 q Q was obtained from a simultaneous γ-ray anisotropy measurement on the succeeding 20Ne transition. Utilising a calculated field gradient of the fluorine atom, an fQ = 4.6% is determined. This value is compared with literature data of similar compounds.
In this paper equilibrium models for the calculation of the excess Gibbs free energy of binary liquid mixtures are developed, the component A of which undergoes chain-forming self-association whilst the component B acts as an 'inert' solvent. It is shown that the extension of the well-known chain-association model of Mecke and Kempter, in which the probability of chain prolongation is assumed to be independent of chain length, is unable to establish satisfactory results because it does not exhibit sufficient unsymmetry. Reduction of the probability of chain growth with in-creasing chain length leads to an improved model with the geometric series replaced by the exponential series. This model, in which only two parameters are used, i. e. the equilibrium constants K for mutual solvation of A and B, and ρ for self-association of A, allows fitting of isothermal experimental GE /R T literature data on cycloalkanol-cycloalkane, alkanol-alkane, and NMF -CCl4 systems within the limits of experimental error. Compared with the two-parameter Wilson equation which gives equally small standard deviations, our equilibrium model has the advantage of allowing passage from GE to HE data and of being applicable to liquid-liquid equilibria.
An improved two-center model has been used to describe the elastic scattering potentials for the collision of identical nuclei. The macroscopic-microscopic approach includes liquid drop (LD) deformation energies, shell corrections and pairing energy corrections. As basis for the microscopic part a two-center shell model has been used with a Hamiltonian including a Thomas-type spin-orbit potential and an l2 correction term. The model is applied to the sudden and adiabatic type of scattering process, including a compression energy term in the LD part for the former case. Results are given as potential energy surfaces for the adiabatic scattering process and potential energy curves for the sudden scattering process.