Metal binding induces conversion of B- to the hybrid B-Z-form in natural DNA

Highly polymerized herring testis DNA of the random nucleotide sequence has been studied in solution by circular dichroism and ultra-violet absorption spectrometry under various experimental conditions. At low temperature upon addition of 0.05 M NaCl or 1.15 M MgSO4 the DNA formed a helix that belonged to the B-family. As the temperature was increased a transition from the pure B- to the hybrid B-Z-form occurred in the presence of 1.15 M MgSO4. This transition occurred over a large range of temperatures and corresponded to a non-cooperative conformational change. A similar DNA transition was induced with 0.098 mM Co(NH3)6Cl3. However, in the presence of 5.3 M NaCl the DNA conformation was not similar to that observed in 1.15 M MgSO4 or 0.098 mM Co(NH3)6Cl3 independently on the environmental temperature. In 5.3 M NaCl the DNA is thought to undergo a transition from one to another right-handed conformation that could be intermediate partially dehydrated conformer arising on the first step in the sequential transition to the dehydration of the polynucleotide. Our results show that a realistic model of native DNA, bearing Z-tracts embedded in B-helixes, can be obtained upon binding of alkaline earth or transition metals. © 2008 Elsevier B.V. All rights reserved

Metal binding induces conversion of B- to the hybrid B-Z-form in natural DNA

Highly polymerized herring testis DNA of the random nucleotide sequence has been studied in solution by circular dichroism and ultra-violet absorption spectrometry under various experimental conditions. At low temperature upon addition of 0.05 M NaCl or 1.15 M MgSO4 the DNA formed a helix that belonged to the B-family. As the temperature was increased a transition from the pure B- to the hybrid B-Z-form occurred in the presence of 1.15 M MgSO4. This transition occurred over a large range of temperatures and corresponded to a non-cooperative conformational change. A similar DNA transition was induced with 0.098 mM Co(NH3)6Cl3. However, in the presence of 5.3 M NaCl the DNA conformation was not similar to that observed in 1.15 M MgSO4 or 0.098 mM Co(NH3)6Cl3 independently on the environmental temperature. In 5.3 M NaCl the DNA is thought to undergo a transition from one to another right-handed conformation that could be intermediate partially dehydrated conformer arising on the first step in the sequential transition to the dehydration of the polynucleotide. Our results show that a realistic model of native DNA, bearing Z-tracts embedded in B-helixes, can be obtained upon binding of alkaline earth or transition metals. © 2008 Elsevier B.V. All rights reserved

EFFECTS OF AMLODIPIN AND METOPROLOL ON AUTONOMIC SYSTEM IN EMOTIONAL AND COLD TESTS IN HYPERTENSIVE PATIENTS WITH DIFFERENT PSYCHOLOGICAL PROFILE

Aim. To asses effects of amlodipin and metoprolol on autonomic system in emotional and cold tests in hypertensive patients with different psychological profile (PP) Material and methods. 61 patients with arterial hypertension of II grade were observed. Therapy with amlodipin or metoprolol was prescribed and allowed to reach target blood pressure (BP) level in all the patients. Patients were divided into 2 groups: 1-st one – patients with normal PP, 2-nd group – patients with subclinical depression. Patients were examined before and 30 days after therapy. Examination included ambulatory BP monitoring, assessment of autonomic status by variational intervalometry and spectral analysis of heart rate variability (HRV) in cold and emotional tests. Depression and anxiety levels were determined with Bek’s and HADS scales.  Results. Treatment with amlodipin  and metoprolol can result in improvement, worsening or unchanging of PP.  In hypertensive patients with subclinical depression improving their PP resulted in autonomic reaction change: sympathetic activity increases and reaction on stress becomes more adequate. If subclinical depression occurred in hypertensive patients because of amlodipin and metoprolol therapy, sympathetic system stress-reaction decreased and parasympathetic influence increased. Conclusion. The study results show necessity of psychometric examination of hypertensive patients in order to reveal subclinical depression and anxiety

Outer-sphere interactions between octahedral chiral cobalt(III) complexes and water-soluble calixarenes

The structures and stability of outer-sphere associates of sulfonate derivatives of thiacalix[4]arene and calix[4]resorcinarene with coordinatively saturated cobalt(iii) bis- and tris-chelates ([Co(L-His)2] +, [Co(en)2ox]+, [Co(en)3] 3+, and [Co(dipy)3]3+) were compared based on the data from UV, CD, 1D 1H NMR, and 2D (2D NOESY) 1H NMR spectroscopy and conductometry. Outer-sphere association is accompanied by partial penetration of the chelate rings of the complexes into the hydrophobic cavity of calixarene, which induces changes in the spectroscopic and spectropolarimetric properties of the cobalt(iii) complexes

Cytoprotective effect of fullerene C<inf>60</inf> derivatives with different structures

Transmembrane potential of mitochondria is a sensitive biomarker of metabolic activity of cells. Here, we studied mitochondrial potential Ψm in Yarrowia lipolytica yeast cells treated with two fullerene C60 derivatives: bis-nitroxide methanofullerene and 3-phospho-pentafullerene acid. Transmembrane mitochondrial potential was measured by vital ratiometric cationic fluorochrome JC-1 using flow cytometry. The fullerene C60 derivatives tested in a concentration of 10 μg/ml developed cytoprotective effect in the yeast cells challenged either with non-ionic detergent tween-80, or Tris-buffer, pH 9.0. Treatment with bis-nitroxide methanofullerene resulted in a 6-fold increase in proportion of cells with high Ψm, while 3-phospho-pentafullerene acid evoked a 1,5-fold increase in this subset compared to the stressed cells. Hence, both fullerene derivatives counteract Ψm dissipation in challenged cells

New calix[4]arene-based amides - Their synthesis, conformation, complexation

New chiral calix[4]arene-based diol-diamides 1a, 1b, tetraamides 2a, 2b and 7 as well as achiral diamide 3 and tetraamides 4-6 were prepared. The conformation of 1 has been studied in solution by NMR and in solid state by X-ray crystallography. The pinched-cone conformation of the calix[4]arene skeleton in 1 was found to be stabilized by a circular array of hydrogen bonds formed by two phenolic O-H and two amidic N-H bonds at lower rim. Whereas no significant complexation of Na+ was observed in solution for diamides 1 and 3, tetraamides 2, 4, 5, and 6 give strong complexes with Na+ as confirmed by NMR titrations of 2 and 4. The influence of anions and the solvents used on complexation ability of 2 towards Na+ is negligible

The dissociation catastrophe in fluctuating-charge models and its implications for the concept of atomic electronegativity

We have recently developed the QTPIE (charge transfer with polarization current equilibration) fluctuating-charge model, a new model with correct dissociation behavior for nonequilibrium geometries. The correct asymptotics originally came at the price of representing the solution in terms of charge-transfer variables instead of atomic charges. However, we have found an exact reformulation of fluctuating-charge models in terms of atomic charges again, which is made possible by the symmetries of classical electrostatics. We show how this leads to the distinguishing between two types of atomic electronegativities in our model. While one is a intrinsic property of individual atoms, the other takes into account the local electrical surroundings. This suggests that this distinction could resolve some confusion surrounding the concept of electronegativity as to whether it is an intrinsic property of elements, or otherwise.Comment: 17 pages, prepared for "Proceedings of QSCP-XIII" in Prog. Theor. Chem. Phy

The multipole polarizabilities and hyperpolarizabilities of the water molecule in liquid state: an ab initio study

Ye