Fig. 1 shows the sample preparation.

Sample preparation.

Sample preparation of CSPI_F: 200 g Fujipro-F was dissolved in 1800 g of distilled water at 5000 rpm for 3 min using a homogenizer (MARK II Model 2.5, Primix, Hyogo, Japan). The obtained sample was named ‘CSPI_F.’.
Sample preparation of CSPI_A: 21.8 g arginine (equivalent to 0.25 M in 500 mL) was added to 300 g 10 wt% CSPI_F. Then, the arginine and CSPI_F mixture was well stirred by a homogenizer at 5000 rpm for 3 min. 10 wt% CSPI_F was then added to the arginine and CSPI_F mixture for a total volume of 500 mL. The mixture of 50 g was placed in a 100-mL heat-resistant pressure bottle, and then the bottle was heated to 121 °C for 10 min by an autoclave (HICLAVE HG-50, Kitahama Manufacturing, Osaka, Japan). The bottles were cooled under running water for 30 min after heating. The mixture was placed in a MWCO 3500 g/ L dialysis tube. Dialysis was performed three times to remove ions and small molecules. The final electrical conductivity of the distilled water side was < 0.1 mS/cm. The obtained sample was named ‘CSPI_A.’.
Sample preparation of CSPI_U: 120.1 g urea (equivalent to 4.0 M in 500 mL) was added to 300 g of 10 wt% CSPI_F. 10 wt% CSPI_F was then added to the urea and CSPI_F mixture for a total volume of 500 mL. Then, the sample was heated in the same manner as the preparation of CSPI_A. After that, the heated sample was subjected to dialysis, and the obtained sample was named ‘CSPI_U.’.
Sample preparation of CSPI_G: 191.1 g guanidine hydrochrolide (equivalent to 4.0 M in 500 mL) was added to 300 g of 10 wt% CSPI_F. 10 wt% CSPI_F was then added to the guanidine hydrochrolide and CSPI_F mixture for a total volume of 500 mL. Then, the sample was heated in the same manner as the preparation of CSPI_A. Afterward, the heated sample was subjected to dialysis, and the obtained sample was named ‘CSPI_G.’.
Sample preparation of CSPI_H: 50.0 g of 10 wt% CSPI_F was heated in the same manner as the preparation of CSPI_A. Then, the heated sample was subjected to dialysis, and the obtained sample was named ‘CSPI_H.’.
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