In solutions of myofibrillar protein extracted from giant squid (Dosidicus 23 gigas), the size-coarsening process of protein nanofiber is complex. At high 24 temperature (25 o C), nanofiber keeps growth but with two distinguishable patterns, 25 slow rate at the initial stage with t 0.2 and the fast one at the late stage with t 2.3 . The 26 intersection of these two slopes is around 300 min. Meanwhile, protein concentration 27 in solution enhances as well. These behaviors contradict to the prediction of Ostwald 28 ripening. Thus, we call this process as abnormal. These abnormal behaviors come 29 from the conformation change of some types of constitution protein molecules with 30 chemical potential reduction when they dissolve from nanofiber to solution. On the 31 other hand, low temperature (10 o C) depresses this size growth. This observation 32 suggests that temperature regulates protein molecule conformation change in 33 nanofiber. The consequence of this abnormal Ostwald ripening process is that all 34 protein molecules in nanofiber are redistributed. Protein molecules with the absence 35 of conformation change in dissolution accumulate in nanofiber to cause it growing, 36 while the rest concentrates in solution. 37 Wilhelm Ostwald descried the phenomenon of large particle growth in 50 the cost of small one as Ostwald ripening due to the surface tension which is 51 proportional to the particles curvature(1-3). As a result, the solute concentration keeps 52 reduction throughout size-coarsening process. Meanwhile, an essential prerequisite, 53 no molecular conformation change when a molecule transfers from one phase to 54 another, exists but is always ignored. This condition is satisfied in inorganic and 55 organic compounds. However, in protein solutions containing particles with various 56 sizes, it should be cautious to apply Ostwald ripening theory in the size-coarsening 57 process because protein molecules are sensitive to the ambient conditions. Even salt 58 concentration variation could induce protein molecule conformation change(4). Thus, 59it is worth to verify Ostwald ripening theory in protein solutions. 60 The existence of nanofiber in solutions of myofibrillar protein extracted from 61 giant squid (Dosidicus gigas) is verified(5). In order to investigate its size-coarsening 62 process in this solution, 2.73 mg mL -1 myofibrillar protein was diluted 10 times by the 63 buffer solution, and was assessed by the dynamic light scattering (DLS) technique and 64 the fluorescence spectroscopy (FS) technique immediately. 65In Fig. 1a, the pattern of light intensity on time depends on the temperature. High 66 temperature (25 o C) allows the light intensity monotonically growing, while low 67 temperature (10 o C) depresses this growth with almost constant light intensity 68 throughout the experiment. Due to high activity of enzymolysis in myofibrillar protein 69at 25 o C(6), it is necessary to estimate its influence in this study. In Fig, 1b, the 70 apparent concentrations of myofibrillar protein in three...

No abstract