The interaction of chitosan with plasmid DNA was investigated as a function of pH, buffer composition, degree of deacetylation (DDA), and molecular weight (M(n)) of chitosan, using isothermal titration microcalorimetry (ITC). The Single Set of Identical Sites model was used to obtain the enthalpy of interaction, the binding constant, and the stoichiometry of binding. The chitosan-DNA interactio...

The sensitivities of metallophthalocyanine (MPcs: M = Co, Ni, Cu, Zn, and H(2)) chemiresistors to vapor phase electron donors were examined using 50 nm MPc films deposited on interdigitated electrodes. Sensor responses were measured as changes in current at constant voltage. Analytes were chosen to span a broad range of Lewis base and hydrogen bond base strengths. The MPc sensor responses were ...

Using UV-Vis spectrophotometric method the interaction of water soluble phthalocyanine, Cobalt(ΙΙ) 4,4′,4′′,4′′′- tetrasulfophthalocyanine(CoTSPc), with bovine serum albumin (BSA) to determine the formation constant and related thermodynamic functions. The measurements were considered in 1mM sodium phosphate buffer, pH 7.0 and at 5 different temperatures 20, 25, 30, 35 and 40ºC. The results sho...

The documented unfavorable changes of physicochemical properties during lead discovery and optimization prompted us to investigate the present practice of medicinal chemistry optimization from a thermodynamic perspective. Basic principles of binding thermodynamics suggest that discriminating between enthalpy-driven and entropy-driven optimizations could be beneficial. We hypothesize that entrop...

The thermodynamic characteristics of oligosaccharide binding to an antibody binding site that is dominated by aromatic amino acids suggest that the hydrophobic effect contributes substantially to complex formation as well as hydrogen bonding and van der Waals interactions. A detailed titration microcalorimetric study on the temperature dependence of the binding of a trisaccharide, representing ...

Interactions of cationic tetrakis (N,N´,N´´,N´´´-tetramethyltetra-3,4-pyridinoporphyrazinatocobalt(II) (Co(tmtppa)) with synthetic polynucleotides, poly(A-T), poly(G-C) and calf thymus DNA have been characterized in 5 mM phosphate buffer, pH 7.2, by optical absorption and fluorescence spectroscopy. The appearance of hypochromicity effect and the red shift in UV-Vis spectrum of porphyrazine was ...

The thermodynamics of binding of fluoride and cyanide to cytochrome c peroxidase (CCP) and its Asn-82-->Asp mutant (D82CCP) in phosphate and acetate buffer at an ionic strength of 0.15 mol.kg-1 from pH 5.0 to 7.1 were investigated by titration calorimetry at 289 and 297 K. The binding reactions are enthalpically driven. The fluoride-binding constants determined from the titration calorimetry re...

Hemocyanin serves as an oxygen carrier in the hemolymph of the European lobster Homarus vulgaris. The oxygen binding behavior of the pigment is modulated by metabolic effectors such as lactate and urate. Urate and caffeine binding to 12-meric hemocyanin (H. vulgaris) was studied using isothermal titration calorimetry (ITC). Binding isotherms were determined for fully oxygenated hemocyanin betwe...

The development of HIV-1 protease inhibitors has been the historic paradigm of rational structure-based drug design, where structural and thermodynamic analyses have assisted in the discovery of novel inhibitors. While the total enthalpy and entropy change upon binding determine the affinity, often the thermodynamics are considered in terms of inhibitor properties only. In the current study, pr...

The binding between peptides and DNA is often driven by entropic forces. We demonstrate herein a new approach to shift the thermodynamic profile of peptide/DNA binding from entropy to enthalpy driven. This eventually leads to higher compacted DNA aggregates which are important for gene transfection.