L-histidine-assisted ultrasound improved physicochemical properties of myofibrillar proteins under reduced-salt condition - Investigation of underlying mechanisms

Ultrasound-assisted modification of soybean protein isolate with L-histidine: Relationship between structure and function

“…This result may be attributed to the interaction of L-His with the side chains of the proteins, which masked the UV absorption of the aromatic amino acids in the proteins, resulting in a decrease in UV absorption. Similar findings were found by Wu et al [27] . Therefore, the incorporation of L-His resulted in the aromatic amino acid groups in MPs being in a more hydrophobic environment.…”

“…Compared to untreated SPI, sonication resulted in a significantly smaller protein particle size. The ultrasound-induced cavitation effect and physical shear can break the non-covalent bonds between proteins, resulting in the fragmentation of protein particles and reduction of particle size [27] . In addition, adding L-His further reduced the particle size of SPI, which may be due to the ultrasound opening of the protein structure.…”

“…In addition, adding L-His further reduced the particle size of SPI, which may be due to the ultrasound opening of the protein structure. This opening promoted the interaction between the imidazole group of L-histidine and protein side chain, thereby weakening the force between protein molecules and causing the dissociation of protein aggregates [2] , [27] . Similarly, Li et al [14] found that alkaline amino acids enhanced protein solubility and reduced protein particle size by increasing the activation energy of protein aggregation.…”

“…The addition of L-His can increase the pH of the solution, resulting in a higher negative electronegativity for the proteins. When L-His is at a high concentration, it may electrically bind to the proteins, which decreases the value of the protein solution potential [27] .…”

“…For ultrasound-treated proteins, sonication had no effect on the ellipticity of the proteins; thus, their secondary structure remained unchanged ( p > 0.05). For SPI treated with ultrasound synergistically with L-His, the α-helix content of the proteins was significantly reduced, suggesting that adding L-His disrupts the hydrogen bonds that stabilize α-helices and causes a rearrangement of the polypeptide chains [6] , [27] . In general, α-helices are ordered secondary structures of protein molecules.…”