Self-Assembly of Protein and Liquid-Liquid Phase Separation under Shear Stress : Investigations by Phase Contrast Rheoscope

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1.Liquid-Liquid Phase Separation in Elastomeric Protein-Water System : Examinations of Critical CharacteristicsThe most remarkable characteristics of elastomeric protein-water system, temperature-dependent coacervation, can be treated as a liquid-liquid phase separation process with the lower critical solution temperature. For the bovine neck ligamental alpha-elastin-water system, near the concentration of 0.11 mg/ml and the temperature of 21.5ﾟC,critical divergences of the forward scattering intensity and the correlation length were observed by dynamic light scattering experiments. In the present study, critical and off-critical characteristics of the phase separation of alpha-elastin-water system were examined by the light scattering and viscometric measurements as well as by the phase contrast microscopic observations. The phase contrast microscopic observations were useful for the system with high concentration of alpha-elastin and for the late stages of phase separation process.2. … More Assemblies of Phase Contrast RheoscopeSelf-assembly process of elastin precursor, tropoelastin, can be mimicked by the physicochemical molecular aggregation process during the temperature-dependent coacervation of elastomeric protein water system. However, the biological process proceeds in the extracellular space where extremely unusual conditions are realized under shear stress and structural disturbance of solvent. To examine the phase behavior in these conditions, rheoscope was introduced by assembling inverted phase contrast microscope and cone-plate rotary viscometer. Basic arrangements of the rheoscope is that the viscometer with transparent cone attachment is placed on the stage with horizontally positioning of the light sauce and condenser. The rheoscope is capable to measure viscosity and simultaneously observe phase behavior by monitoring the appearances of microcoacervate droplets and by tracing their size and shape transformations. The most noticeable advantages of rheoscope is observations of the phase separation process under regulated shear stress as a model space of the extracellular crevice. Less