Aggregate formation structure spectroscopy

After rehydration, the spectra of both samples are very native-like, indicating that the majority of nonnative molecules have refolded (Figure 3). However, in the spectrum of the sample lyophilized without sucrose, the appearance of a new band near 1625 cm", which is assignable to intermolecular j6-sheet structure, and the decreased intensities in vibrational bands ascribed to a-helix (1656 cm" ) and turn (1688-1665 cm" ) structures, indicate the formation of protein aggregates upon rehydration (see [11] for a detailed review of the study of protein aggregation with infrared spectroscopy). In this sample, 18% of the protein formed insoluble aggregates. In contrast, in the sample lyophilized with sucrose, only 9% insoluble aggregate was noted after rehydration. This reduction in... 

Ultrasonic spectroscopy allows measuring a wide variety of liquid systems, from dilute to concentrated solutions, and can be used to monitor processes such as molecular structural changes, thermal transitions, chemical reactions, aggregation formation, crystallisation, etc. Attenuation measurements are used for particle sizing in emulsions and suspensions and for kinetics of fast chemical reactions. 

The micelle formation process and structure can be described by thermodynamic functions (AG°mjc, AH°mjc, AS°mic), physical parameters (surface tension, conductivity, refractive index) or by using techniques such NMR spectroscopy, fluorescence spectroscopy, small-angle neutron scattering and positron annihilation. Experimental data show that the dependence of the aggregate nature, whether normal or reverse micelle is formed, depends on the dielectric constant of the medium (Das et al., 1992 Gon and Kumar, 1996 Kertes and Gutman, 1976 Ward and du Reau, 1993). The thermodynamic functions for micellization of some surfactants are presented in Table 1.1. 

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