• Bulletin of the Korean Chemical Society
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• v.28 no.5
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• pp.730-736
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• 2007

The interaction of a polyoxometal (POM), K6SiW11Co(H2O)O39.10H2O (K6) as a Keggin, with human serum albumin (HSA) was studied by different methods and techniques. Binding studies show two sets of binding sites for interaction of POM to HSA. Binding analysis and isothermal calorimetery revealed that, the first set of binding site has lower number of bound ligand per mole of protein (ν), lower Hill constant (n), higher binding constant (K), more negative entropy (ΔS) and more electrostatic interaction in comparison to the second set of binding site. In addition, differential scanning calorimetery (DSC) and spectrophotometery data showed that, there are two energetic domains. The first domain is less stable (lower Tm and Cp) which corresponds to the tail segment of HSA and another with more stability is related to the head segment of HSA. Polyoxometal also decreases the stability of protein as Tm, secondary and tertiary structure as well as quenching of the fluorescence decrease. On other hand, perturbations in tertiary structure are more than secondary structure.

• Preventive Nutrition and Food Science
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• v.15 no.4
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• pp.356-359
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• 2010

Glass transition phenomena in nine Korean pure honeys (moisture content 18.3~20.1%) and honey-water mixtures by different water contents (0, 2, 5, and 10% w/w) were investigated with modulated different scanning calorimetry (MDSC). The total, reversing, and non-reversing heat flows were quantified during heating using MDSC. Glass transition was observed from reversing heat flow separated from the total heat flow. The glass transition temperatures ($T_g$) of pure honeys, which are in the range of $-42.7^{\circ}C$ to $-50.0^{\circ}C$, varied a lot with low determination coefficient ($R^2$=0.63), whereas those of honey-water mixtures decreased with a decrease in honey content. The $T_g$ values were also more significantly different among honey-water mixtures when compared to pure honeys, indicating that in the honey-water mixture system the $T_g$ values appear to be greatly dependent on moisture content. The measured heat capacity change (${\Delta}C_p$) was not influenced by moisture content.