L.A. Wasserman

Influence of growth temperature on the structure and thermodynamic parameters of barley starches

Barley starches grown at different temperatures were investigated using high sensitivity differential scanning microcalorimetry and X-ray diffraction. By applying physico-chemical approaches, thickness of crystalline lamellae, thermodynamic and structural characteristics (such as gelatinisation) of cooperative units and parameters characterising thermodynamic properties of crystal surfaces were determined. It was established that a difference of growth temperature experienced by plants during development does not lead to changes in the thickness of amylopectin crystalline lamellae and hence constituent double helix length. The role of defects in structural organisation of native barley starches is discussed. It is suggested that not all fatty acids necessarily form crystalline inclusion complexes.

Thermodynamic and structural properties of starches extracted from potatoes grown at different environmental temperatures

Potato starches grown at different temperatures were investigated using high sensitivity differential scanning microcalorimetry (HSDSC) and Fourier transform infrared spectroscopy (FTIR). By applying physico-chemical approaches, the thickness of crystalline lamellae and the thermodynamic and structural characteristics (such as gelatinisation) of cooperative units and their surfaces were determined. It was established that a difference of growth temperature experienced by tubers during development does not lead to changes in the thickness of amylopectin crystalline lamellae and hence the constituent double helical length. However, the positive correlation established between growth temperature and gelatinisation temperatures was confirmed as being due to optimisation of crystallite structural organisation (at higher temperatures).

Effect of decane or sodium decanoate on the thermodynamics of globular protein solutions

Abstract The elucidation of the effect of decane or sodium decanoate (models of the nonpolar or polar lipids) on the molecular parameters and thermodynamic properties of proteins has been carried out in binary (protein-solvent) and ternary (protein-protein-solvent) aqueous solutions. Ovalbumin and 11S globulin, globular proteins of well-known structure, were considered. Light-scattering data manifest protein association in aqueous medium under the influence of both decane and sodium decanoate. Association of protein molecules in aqueous medium is higher under the influence of the nonpolar decane molecules. The thermodynamic parameters for different types of pair interactions in the systems ( the second virial coefficients) were estimated from static light-scattering data in the binary and ternary aqueous solutions of biopolymers without and with decane or sodium decanoate. The values of the second virial coefficients obtainedfrom binary solutions exhibit high thermodynamic affinity of protein associates formed under the influence of decane or sodium decanoate for aqueous medium. Maximal thermodynamic affinity of the protein associates for the solvent was observed in the case of the polar sodium decanoate added to the proteins. The values of the cross second virial coefficients obtained from ternary solutions indicate that the addition of the nonpolar decane molecules to the proteins increases the strength of the thermodynamically unfavorable interactions between protein molecules that are different in nature. On the other hand, the addition of polar sodium decanoate to the proteins leads to a decrease in the thermodynamically unfavorable protein-protein pair interactions in aqueous medium. The influence of the decane or sodium decanoate on the conformational state of the proteins in aqueous medium was characterized by differential scanning microcalorimetry. The data obtained manifest significant changing of the conformational stability of the protein globule under the influence of decane or sodium decanoate. The character of this influence strongly depends on the nature of both the low-molecular-weight organic compounds and the proteins studied.

Spin probes in micellar and polymer self-associating systems

The results of studies of micellar and self-associating polymer systems by spin probe ESR spectroscopy are summarized. The local dynamics and structures of low-molecular-weight micelles built of cationic surfactants bearing long alkyl chains (from C16 to C22), gels of hydrophobically modified polymers, polymer micelles, micellar complexes of nonionic surfactant (Brij58) with hydrogels based on polyacrylic acid, and associates formed in aqueous solutions of poly(diphenylenesulfophthalide) are discussed. Interest in these systems is caused by prospects of their practical use as carriers in drug delivery, in biotechnology, for the enhancement of oil production, and in other purposes.

Thermodynamic characteristics of supramolecular complexes of aroma compounds with ordered structures of polysaccharides of corn starch and its cryotextures

Supramolecular complexes of organic odorants (n-octanol and n-octyl acetate) with polysaccharides of corn starch, its cryotextures, and waxy corn starch cryotextures were studied by differential scanning microcalorimetry. It was shown that complexes are formed with amylose-containing starch and no complexes are formed with amylopectin starch. The melting enthalpies of the complexes were determined. It was shown that complexes of the odorants with native corn starch and its cryotextures have different thermodynamic characteristics.