Myofibrillar protein can form a thermo‐reversible gel through elaborate deamidation using protein‐glutaminase

Abstract

BACKGROUND Novel thermo‐reversible hydrogels that undergo gelation in feedback to external stimuli have numerous applications in the food, biomedical, and functional materials fields. Muscle myofibrillar protein (MP) has long been known for thermally irreversible gelation. Once the reversible gelation of MP is achieved, its scope for research and application will expand. RESULTS The work reported here achieved, for the first time, a thermo‐reversible MP gelation by elaborate deamidation using protein glutaminase (PG). The protein concentration and PG reaction time within windows of 1.0–2.5% and 8 h or 12 h were observed to be vital for creating thermo‐reversible gels. The gel strength increased with protein concentration. The gel displayed a perforated lamellar microstructure, which resulted in a high water‐holding capacity. The rheological results revealed the thermo‐reversibility of the gel was robust for up to five cycles of heating and cooling. The thermally reversible gelation is closely related to the reversible assembly between individual α‐helix and helical coiled coil. Hydrophobic interactions proved to be predominantly involved in the formation and stabilization of the gel network structure. CONCLUSION This work increases the scope of research into the thermo‐responsive behavior of MP‐based gel. It can foster advances in research into the applications of muscle proteins and into the use of PG as a novel ingredient in the food industry. © 2022 Society of Chemical Industry.

L‐histidine inhibits the heat‐induced gelation of actomyosin in a low ionic strength solution

“…Hydrophobic interactions are considered one of the important bounding modes of the heat-induced gel network of actomyosin (Cao et al, 2012;Zhang, Chen, et al, 2022). The increase in surface hydrophobicity by heating was due to the unfolding of protein molecules, leading to the exposure of some of the non-polar amino acid side chains (Gao et al, 2019).…”

“…However, in the presence of L‐histidine, the surface hydrophobicity of actomyosin was stable up to 50°C; whereas, in the absence of L‐histidine, the surface hydrophobicity significantly increased after 40°C. Hydrophobic interactions are considered one of the important bounding modes of the heat‐induced gel network of actomyosin (Cao et al, 2012; Zhang, Chen, et al, 2022). The increase in surface hydrophobicity by heating was due to the unfolding of protein molecules, leading to the exposure of some of the non‐polar amino acid side chains (Gao et al, 2019).…”

Thermo-reversible gelation of myofibrillar protein: Relationship between coiled-coil and thermal reversibility

“…The deamidation of MP was performed as previously described ( Fu et al, 2022 ; Zhang et al, 2022 ). MP (25 g/L, pH 7.0) was treated with PG (16 U/g protein) at 37 °C for 12 h. Afterward, samples were moved to an ice slurry bath (∼4 °C) promptly with the purpose of deactivating PG.…”

“…( Choy et al, 2003 ). The parameters of the temperature scanning experiment were set according to previous studies ( Zhang et al, 2022 ).…”

“…The myosin rod domain is typical of the CC structure, implying that myosin thick filament is rich in CC nanofibrillar structures. Recently, thermally reversible gels from myofibrillar protein were pioneerly reported by our group ( Zhang et al, 2022 ). After more than five cycles of heating and cooling, gel demonstrates thermal reversibility.…”