Molecular simulation of partially denatured β-lactoglobulin

From Elsevier via Jisc Publications RouterHistory: accepted 2023-04-22, issued 2023-04-29Article version: AMPublication status: AcceptedFunder: Heriot-Watt University; FundRef: https://doi.org/10.13039/100009767Funder: Engineering & Physical Sciences Research Council; Grant(s): EP/J501682/1Julien Lonchamp - ORCID: 0000-0001-7954-4745 https://orcid.org/0000-0001-7954-4745The unfolding of β-lactoglobulin (β-lac) upon heating was comprehensively studied through molecular dynamics computer simulations. A β-lac molecule in the aqueous solution was firstly heated at 500 K for unfolding and then annealed at 300 K to collect stable conformations. There were five meta-stable conformations observed based on the Free Energy Landscape (FEL). The β-lac molecule was found to exhibit an open and extended conformation on heating followed by limited refolding upon cooling. The cysteine residues –SH121 and S–S66-160 in the most open conformation were located at the opposite ends of the β-lac molecule. This would favour the intermolecular –SH/S–S interchange reactions that are known to occur in β-lac as part of the inter-molecular aggregation process. Furthermore, the unfolding of the β-lac increased the hydrogen bond forming capacity between water molecules and the protein and between water molecules themselves. The interactions and the properties of the water molecules in the protein hydration shell also indicated that the hydration shell was stabilized by protein unfolding. However, it was found that the unfolding of β-lac increased diffusion of hydration water molecules, including those in the first hydration shell that interact more strongly with the protein. This may partly explain why unfolded proteins are more likely to aggregate even though there were more hydration water molecules protecting them. Such results provided more detailed information on the structure-functionality relationship of β-lac based on both the protein molecule and its hydration shell. This provides insight into how we can control the processing of proteins for desirable functional properties such as thickening and gelation, which are modified through protein-water interactions.inpressinpres

The Effect of the Isomeric Chlorine Substitutions on the Honeycomb-Patterned Films of Poly(x-chlorostyrene)s/Polystyrene Blends and Copolymers via Static Breath Figure Technique

Polymeric thin films patterned with honeycomb structures were prepared from poly(x-chlorostyrene) and statistical poly(x-chlorostyrene-co-styrene) copolymers by static breath figure method. Each polymeric sample was synthesized by free radical polymerization and its solution in tetrahydrofuran cast on glass wafers under 90% relative humidity (RH). The effect of the chorine substitution in the topography and conformational entropy was evaluated. The entropy of each sample was calculated by using Voronoi tessellation. The obtained results revealed that these materials could be a suitable toolbox to develop a honeycomb patterns with a wide range of pore sizes for a potential use in contact guidance induced culture.This research was funded by the Government of Basque Country, grant ELKARTEK FRONTIERS KK-2017/0096 and grant Grupos de Investigacion IT718-13

BODIPY-based conjugated microporous polymers as reusable heterogeneous photosensitisers in a photochemical flow reactor

Production of singlet oxygen at 530 nm in a flow reactor using novel BODIPY-based polymers as heterogeneous photosensitisers.</p

Properties of partially denatured whey protein products: Formation and characterisation of structure

Item previously deposited in Heriot-Watt University repository: https://researchportal.hw.ac.uk/en/publications/properties-of-partially-denatured-whey-protein-products-formationPartially denatured whey protein (PDWPC) products have been manufactured using a controlled heating process that allows control of the degree of denaturation of the whey proteins. This is assessed by following the change in free sulphydryl content of the protein as heating progresses. This allows the formation of soluble whey protein aggregates of diverse particle size and morphology. The PDWPC's have been made using different manufacturing conditions (temperature, pH, degree of denaturation) to give aggregated PDWPC powders with a degree of denaturation in the range 45–98% and particle size 3–17 μm. Particle size analysis, scanning electron microscopy and density analysis show that the particles have aggregated structures that range from compact, particulate gel-like to fibrillar phase-separated structures, with intermediate structures formed under some conditions. These structures are consistent with the known gel structures formed in whey protein concentrate gels. The structure of the PDWPC particles differs from that of microparticulated whey proteins. The possibility of using PDWPC's as ingredients tailored to the needs of food manufacturers is discussed.https://doi.org/10.1016/j.foodhyd.2015.06.00952pubpu

Properties of partially denatured whey protein products 2: Solution flow properties

Partial denaturation of whey protein concentrates has been used to make protein powders with differing viscosity properties. PDWPC particles have been manufactured to have a range of aggregate sizes (3.3–17 μm) and structures (compact particle gel to open fibrillar gel). In solution the PDWPC samples show complex viscosity behaviour dependant on the size and morphology of the PDWPC aggregate particles. For the same protein content the compact particles have a lower viscosity than open, fibrillar particles. The viscosity also appears to depend on the surface structure of the particles, with particles of a similar size, but having a rougher surface giving higher viscosity than similar smooth particles. The viscosity of the WPC, MPWPC and PDWPC solutions are explained in terms of the postulated interactions between the protein aggregates in solution.Engineering & Physical Sciences Research Council grant No. EP/J501682/1.https://doi.org/10.1016/j.foodhyd.2015.12.01256pubpu

Polymer-Supported Photosensitizers for Oxidative Organic Transformations in Flow and under Visible Light Irradiation

A 2,1,3-benzothiadiazole (BTZ)–based vinyl crosslinker was synthesized and copolymerized with large excesses of styrene using free radical polymerization to deliver heterogeneous triplet photosensitizers in three distinct physical formats: gels, beads and monoliths. These photosensitizers were employed for the production of singlet oxygen (1O2) and for the aerobic hydroxylation of aryl boronic acids via superoxide radical anion (O2˙-) whereby the materials demonstrated good chemical and photo stability. BTZ-containing beads and monoliths were exploited as photosensitizers in a commercial flow reactor, and 1O2 production was also demonstrated using direct sunlight irradiation, with a conversion rate comparable to the rates achieved when using a 420 nm LED module as the source of photons

Chain conformation of a main-chain thermotropic liquid crystalline polymer

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