1Division of Applied Biosciences, Graduate School of Agriculture, Kyoto University, Sakyo Kyoto 606-8502, 2Central Research Laboratory, Nippon Suisan Kaisha Ltd., Hachioji, Tokyo 192-0991, Japan
To verify the effects of hydrophobic structures on gel formation in fish gel products, we performed a thermal shift assay to determine the exposure of hydrophobic structures during heat denaturation of fish actomyosin. The thermal shift assay is used to detect hydrophobic structures generated by heat denaturation of 7 proteins by using a specific fluorescence dye such as SYPRO® Orange. Five major findings of this study are as follows: (1) Hydrophobic structures were intensively exposed at around 58℃ irrespective of the fish species. (2) The temperature that caused the intensive exposure of hydrophobic structures was not correlated with the temperature of the water inhabited by the fish. (3) Hydrogen bonds and disulfide bonds possibly contribute to the heat stability of fish actomyosin. (4) Heat denaturation of fish actomyosin is not completely reversible; heat-denatured fish actomyosin demonstrated a different pattern of exposure of hydrophobic structures compared to those exhibited by non-heated actomyosin. (5) Lastly, direct contribution of the α-helix structure to hydrophobicity was ruled out because heating gradually induced a reduction in the α-helix structure despite the sudden exposure of hydrophobic structures induced at around 58℃.