New insights into heat induced structural changes of pectin methylesterase on fluorescence spectroscopy and molecular modeling basis

Structural and functional changes of the protein β-lactoglobulin under thermal and electrical processing conditions

In the present study we have tried to explore the effect of static external electric field of strength 3.0 V/nm on the conformational changes adopted by the protein β-lactoglobulin. We have chosen different temperatures viz. 300 K, 400 K and 450 K to evaluate the temperature dependent effect of electric field. We have observed that combined effect of high temperature and static external electric field show significant changes on the structural conformation of the protein which in turn may affect the functional properties of the protein. Calculations of root mean square deviations reveal that both helical and β-sheet regions of the protein are noticeably affected at high temperature. We have used solvent accessible surface area (SASA) and dipole moment values to explain that there is changes in hydrophobicity of the protein surface due to presence of external electric field. The study reveals that electric field in combination with high temperature can be used to alter the conformation of the protein and the effect of external electric field is more pronounced at high temperature than that of low temperature. The study provides a better understanding of the conformational changes adopted by the protein under the stress of external electric field and high temperature and provide guidance to choose optimum conditions for processing without loss of nutritional properties.

Contribution of Special Structural Features to High Thermal Stability of a Cold-Active Transglutaminase

A cold-active transglutaminase (TGase, EC 2.3.2.13) that catalyzes the reaction of protein glutamine + protein lysine ↔ protein with γ-glutamyl-ε-lysine cross-link + NH₃ at low temperatures was reported previously. This study verified the thermal stability of the TGase from 0-80 °C. Fluorescence and CD spectra studies confirmed tertiary structural damage at 40 °C, α-helix reduction at 60 °C, and refolding during cooling to 20 °C. The TGase sequence was obtained by transcriptomics and used to build its structure. Its catalytic triad was Cys333-His403-Asp426 and its catalytic process was inferred from the model. Molecular dynamics simulation illustrated that its cold activity resulted from its flexible active site, while high thermostability was conferred by an overall rigid structure, a large amount of stable Val and Lys, and strong electrostatic interactions at the N- and C- terminals. This study fills gaps in the correlation of conformational changes with stability and activity of TGase.

Molecular Dynamics Simulation for Mechanism Elucidation of Food Processing and Safety: State of the Art

Molecular dynamics (MD) simulation is a useful technique to study the interaction between molecules and how they are affected by various processes and processing conditions. This review summarizes the application of MD simulations in food processing and safety, with an emphasis on the effects that emerging nonthermal technologies (for example, high hydrostatic pressure, pulsed electric field) have on the molecular and structural characteristics of foods and biomaterials. The advances and potential projection of MD simulations in the science and engineering aspects of food materials are discussed and focused on research work conducted to study the effects of emerging technologies on food components. It is expected by showing key case studies that it will stir novel developments as a valuable tool to study the effects of emerging food technologies on biomaterials. This review is useful to food researchers and the food industry, as well as researchers and practitioners working on flavor and nutraceutical encapsulations, dietary carbohydrate product developments, modified starches, protein engineering, and other novel food applications.