The Evidence of Cooperative Binding of a Ligand to G4 DNA

Intrinsic constants of the ligand binding with G4 DNA (guanine-rich DNA sequence) using quantitative standards can be convenient providing the assessment for elucidating the possibility of such structures participation in biochemical processes. In the present communication, the hard + soft modelling approach to calculate intrinsic constants of a ligand binding with short DNA molecule, particularly such as G4 DNA, has been proposed. The suggested approach has focused upon the quantitative evaluating of a mutual influence between sites and between bound ligands. The cross-validation between a new hard + soft modelling and conventional stepwise complex formation algorithm has been conducted. A number of simulated examples will illustrate the methodology. The experimental mole-ratio titration of TMPyP4 by G4 DNA [(CG3)2CGC(AG3)2G] has been reexamined. The [(CG3)2CGC(AG3)2G] that folds from a G-rich sequence found in the promoter region of c-kit oncogene can be considered as a molecule with two equivalent mutually influence binding sites

Spectrometric study of the oligodeoxyribonucleotide protonation in aqueous solution

UV absorption spectra and circular dichroism spectra of aqueous solutions of cytosin- and thyminecontaining single-stranded Oligodeoxyribonucleotide 5'-CCTTTCCTTTTCCTTTCC-3'(ckit4) were measured at various рН in the range 3.3–8.9. The chemometric analysis of the multiinstrumental data matrix was carried out. The diagrams of relative contents of complex forms of the DNA molecule absorbing in the studied wavelength range (220–320 nm) were constructed by the ALS–MCR soft simulation procedure without initial postulation of their chemical compositions. The model of equilibrium complex formation describing observed changes in the spectra depending on the solution acidity was developed on the basis of the matrix method. Intrinsic protonation constants of the oligonucleotide ckit4 were calculated. The formation of intramolecular complexes between cytosine С.С+ bases in the studied DNA molecule is of a cooperative nature, and their subsequent protonation is an anticooperative process.Peer reviewe

Oregano production under various water depths estimated by means of the class A pan evaporation Produção de orégano com diferentes lâminas de irrigação estimadas a partir da evaporação do tanque classe A

The purpose of this experiment was to analyze the effect of five irrigation water depths on oregano production. Oregano is a plant rich in essential oil, commonly used as seasoning in food preparation. The water depths were estimated based on the class A pan evaporation (CPE): 0 CPE (without water replacement); 25 CPE, 50 CPE, 75 CPE, and 100% CPE. The analyzed variables were fresh and dry weight of leaves and roots, yield, net return, and water use efficiency. The experiment was carried out in Presidente Prudente, São Paulo State, Brazil, from February to May 2006. The best results for all the studied variables were found when 100% CPE was used. A linear positive relation was observed between water increments and fresh and dry weight of both the aboveground part and roots. The use of a water depth corresponding to 100% CPE resulted in the maximum productivity (8,089.7 kg ha-1), and in the highest net annual return (R$57,637.87 ha-1).<br>Foi analisado o efeito de cinco lâminas de irrigação na produção do orégano, planta rica em óleo essencial, muito usada como tempero na preparação de alimentos. As lâminas de água foram baseadas na evaporação do tanque classe A (ECA) sendo: 0 ECA (sem reposição de água); 25 ECA; 50 ECA; 75 ECA e 100$ 57.637,87 ha-1)