Strong solute-solute dispersive interactions in a protein-ligand complex

The contributions of solute-solute dispersion interactions to binding thermodynamics have generally been thought to be small, due to the surmised equality between solute-solvent dispersion interactions prior to the interaction versus solute-solute dispersion interactions following the interaction. The thermodynamics of binding of primary alcohols to the major urinary protein (MUP-I) indicate that this general assumption is not justified. The enthalpy of binding becomes more favorable with increasing chain length, whereas the entropy of binding becomes less favorable, both parameters showing a linear dependence. Despite the hydrophobicity of the interacting species, these data show that binding is not dominated by the classical hydrophobic effect, but can be attributed to favorable ligand-protein dispersion interactions.     

A comparative investigation of the fatty acid compositions of the seeds of a number of lines of a genetic collection of Gossypium hirsutum

A comparative analysis has been made of the amounts of lipids and their fatty-acid compositions in the seeds of the lines of agenetic collection of cotton plants of the speciesGossypium hirsutum and their hybrids and the variety Tashkent-1. The results obtained on the fatty-acid compositions of some hybrids make it possible to recommend the use of individual lines of cotton plants as donors for improving the food-value indices of cottonseed oil.Institute of Chemsitry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. V. I. Lenin Tashkent State University. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 173–176, March–April, 1991.     

Comparison of thermal characteristics of materials examined by thermogravimetry and flammability tests

This paper deals with the examination of various types of flame resistant fabric in fire conditions, standard flammability tests and thermogravimetry. It shows how it may be possible to determine the protection afforded by a garment using very small samples and instrumental laboratory techniques. This could be important in the development of new materials where a quick assessment could be made of the protective qualities of the material.

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Zusammenfassung Es wird die Prüfung verschiedener feuerfester Gewebe unter Feuerbedingungen bei standardisierten Entzündbarkeitsprüfungen und durch Thermogravimetrie beschrieben. Es wird gezeigt, wie der durch ein Kleidungsstück gewährleistete Schutz mit sehr kleinen Proben und durch Laboratoriumstechnik bestimmt werden kann. Dies könnte bei der Entwicklung neuer Materialien von Wichtigkeit sein, wo eine Schnellbestimmung der Schutzeigenschaften des Materials durchgeführt werden muß.

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Résumé On examine différents types d'étoffes ignifuges du point de vue de l'inflammabilité et par thermogravimétrie. On montre la possibilité de déterminer à l'aide des techniques instrumentales de laboratoire, l'action protectrice d'un vêtement en utilisant de très petits échantillons. Cela pourrait être important lors du développement de matériaux nouveaux oú l'on pourrait soumettre à analyse rapide les qualités protectrices des étoffes.

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We wish to express our thanks to the Air Force Materials Laboratory, Air Force Systems Command, U.S. Air Force for the sample of PBI and to the Council and Director of LIRA for their permission to publish this paper.     

Thermodynamics of binding of 2-methoxy-3-isopropylpyrazine and 2-methoxy-3-isobutylpyrazine to the major urinary protein

In the present study we examine the thermodynamics of binding of two related pyrazine-derived ligands to the major urinary protein, MUP-I, using a combination of isothermal titration calorimetry (ITC), X-ray crystallography, and NMR backbone (15)N and methyl side-chain (2)H relaxation measurements. Global thermodynamics data derived from ITC indicate that binding is driven by favorable enthalpic contributions, rather than the classical entropy-driven hydrophobic effect. Unfavorable entropic contributions from the protein backbone and side-chain residues in the vicinity of the binding pocket are partially offset by favorable entropic contributions at adjacent positions, suggesting a "conformational relay" mechanism whereby increased rigidity of residues on ligand binding are accompanied by increased conformational freedom of side chains in adjacent positions. The principal driving force governing ligand affinity and specificity can be attributed to solvent-driven enthalpic effects from desolvation of the protein binding pocket.     

Variants on the Berz sublinearity theorem

Aequationes mathematicae - We consider variants on the classical Berz sublinearity theorem, using only DC, the Axiom of Dependent Choices, rather than AC, the Axiom of Choice, which Berz used. We...     

Structural studies of iron in vitrified toxic wastes

The formation of iron carbides by reactive milling of α-Fe and C powders is reported. The products formed were analyzed by Mössbauer spectroscopy and X-ray diffraction. It was found that iron carbide phases start forming after an incubation period of about 3 h depending on the ball-to-powder weight ratio (BPR). Carbide amounts increased with increasing milling time while α-Fe content decreased. Energy transfer increased with increasing BPR and high BPR resulted in an increase in the reaction rate. Although it was not possible to selectively synthesise a specific Fe _x C phase, samples containing predominantly one type of carbide phase, either Hägg carbide or cementite, were successfully prepared. The formation of the different iron carbide phases is discussed within the context of the Fe–C phase diagram for non-equilibrium processes.