Conformational Transition of Polyelectrolyte As Influenced by Electrostatic Complexation with Protein

Molar mass effect in food and health

It is demanded to supply foods with good quality for all the humans. With the advent of aging society, palatable and healthy foods are required to improve the quality of life and reduce the burden of finance for medical expenditure. Food hydrocolloids can contribute to this demand by versatile functions such as thickening, gelling, stabilising, and emulsifying, controlling texture and flavour release in food processing. Molar mass effects on viscosity and diffusion in liquid foods, and on mechanical and other physical properties of solid and semi-solid foods and films are overviewed. In these functions, the molar mass is one of the key factors, and therefore, the effects of molar mass on various health problems related to noncommunicable diseases or symptoms such as cancer, hyperlipidemia, hyperglycemia, constipation, high blood pressure, knee pain, osteoporosis, cystic fibrosis and dysphagia are described. Understanding these problems only from the viewpoint of molar mass is limited since other structural characteristics, conformation, branching, blockiness in copolymers such as pectin and alginate, degree of substitution as well as the position of the substituents are sometimes the determining factor rather than the molar mass. Nevertheless, comparison of different behaviours and functions in different polymers from the viewpoint of molar mass is expected to be useful to find a common characteristics, which may be helpful to understand the mechanism in other problems.

Quantitative analysis of binding affinities and characterization of β-lactoglobulin and λ-carrageenan as a function of pH

λ-Carrageenan (λcar) interacted with β-lactoglobulin (βlg) immediately to form βlg-λcar complexes when used as an additive in milk. The formation of complexes is the key process through which to explore the bioapplication of λcar, which is a complicated process and influenced by many factors. In this study, the formation process and effect of pH were ascertained by the binding affinity, hydrodynamic diameter, and secondary structure. Results showed that the interaction was spontaneously exothermic and the complexes were soluble. The binding affinities (Ka) decreased from 9.0 ± 1.3 × 10⁵ to 1.3 ± 0.8 × 10⁵  M^-1 , and the stoichiometry also decreased as the pH was increased from 4 to 7. Furthermore, DLS showed a larger hydrodynamic diameter of the complexes at lower pH. Moreover, the complexes induced a change in the secondary structural components of βlg at lower pH. PRACTICAL APPLICATIONS: The secondary structure of βlg was changed by the interaction of λcar, which resulted in βlg-λcar complexes under acidic conditions. The soluble βlg-λcar complexes showed a good stability against aggregation. Thus, they can enhance the textural properties and stability of acidic dairy drinks, and can be used to accurately formulate ingredients in the food ingredient industry.

Involvement of DNA in Gel Formation of Scallop (Patinopecten yessoensis) Male Gonad Hydrolysates and Corresponding Hybrid Gel with κ-Carrageenan

Involvement of DNA in gelation and microstructural properties of scallop (Patinopecten yessoensis) male gonad hydrolysates (SMGHs) and corresponding hybrid gel with κ-carrageenan (SMGHs/κ-C) was studied using DNase pretreatment. Although DNase pretreatment significantly transformed SMGHs from weak gels to liquid, it made SMGHs have a superior synergistic effect on gel formation with κ-C by evidence of 2.7-fold G' and 1.1-fold melting temperature. However, the relaxation time (T₂₁ and T₂₃), functional groups, and flocculation behavior were comparable between SMGHs/κ-C and SMGHs/DNase/κ-C. Moreover, SMGHs/DNase/κ-C exhibited a denser network with more numerous patches and larger void spaces. These results suggest that DNA contributes to the gel formation of SMGHs whereas restricts more cationic peptides in SMGHs to bind sulfate groups in κ-C during gel formation.

Light-sheet microscopy as a tool to understanding the behaviour of Polyion complex micelles for drug delivery

Light sheet microscopy reveals the low stability of polyelectrolyte–protein complexes in spheroids.