Properties of Biodegradable Multilayer Films Based on Plasticized Wheat Starch

Multilayer films based on plasticized wheat starch (PWS) and various biodegradable aliphatic polyesters have been prepared through flat film coextrusion and compression molding. Poly(lactic acid) (PLA), polyesteramide (PEA), poly(μ‐caprolactone) (PCL), poly(butylene succinate adipate) (PBSA), and poly(hydroxybutyrate‐co‐valerate) (PHBV) were chosen as the outer layers of the stratified "polyester/PWS/polyester" film structure. The main goal of the polyester layers was to improve significantly the properties of PWS in terms of mechanical performance and moisture resistance. Since no specific compatibilizer or tie layer were added, the properties of subsequent films rely on the compatibility between the respective materials only. The effects of glycerol content in PWS, polyester type, and film composition on the mechanical properties and adhesion strength of multilayers were investigated. The conditions for optimal product performance were examined. The multilayer films may be suitable for applications in food packaging or disposable articles.     

Understanding the Interactions of Guanine Quadruplexes with Peptides as Novel Strategies for Diagnosis or Tuning Biological Functions

Guanine quadruplexes (G4s) are nucleic acid structures exhibiting a complex structural behavior and exerting crucial biological functions in both cells and viruses. The specific interactions of peptides with G4s, as well as an understanding of the factors driving the specific recognition are important for the rational design of both therapeutic and diagnostic agents. In this review, we examine the most important studies dealing with the interactions between G4s and peptides, highlighting the strengths and limitations of current analytic approaches. We also show how the combined use of high-level molecular simulation techniques and experimental spectroscopy is the best avenue to design specifically tuned and selective peptides, thus leading to the control of important biological functions.     

Exploring Dihydroflavonol-4-Reductase Reactivity and Selectivity by QM/MM-MD Simulations

Flavonoids are secondary metabolites ubiquitously found in plants. Their antioxidant properties make them highly interesting natural compounds for use in pharmacology. Therefore, unravelling the mechanisms of flavonoid biosynthesis is an important challenge. Among all the enzymes involved in this biosynthetic pathway, dihydroflavonol-4-reductase (DFR) plays a key role in the production of anthocyanins and proanthocyanidins. Here, we provide new information on the mechanism of action of this enzyme by using QM/MM-MD simulations applied to both dihydroquercetin (DHQ) and dihydrokaempferol (DHK) substrates. The consideration of these very similar compounds shed light on the major role played by the enzyme on the stabilization of the transition state but also on the activation of the substrate before the reaction through near-attack conformer effects.     

Gas transfer properties of wheat gluten coated paper adapted to eMAP of fresh parsley

Gas transfer properties of wheat gluten (WG) coated paper and their ability to fulfil the requirements in eMAP of fresh parsley were studied. Permeation of gases through WG-paper was demonstrated to be RH-dependent and closely related to structural modification in the WG layer. Formation of micro-cracks was evidenced in dry conditions; but when increasing RH, plasticisation occurs within the protein layer and micro-fractures were reduced until disappearance. This reversible phenomenon allowed the WG-layer to recover its integrity at RH higher than 70%, and the WG character to be expressed in such conditions. When used at 20 °C and 80% RH as part of the packaging of parsley, modified atmosphere was created and a steady state of 11 kPa O₂ and 4.5 kPa CO₂ was reached after 45 h. In such conditions, the overall quality of parsley leaves remained acceptable during 8 days, with only 28% loss of chlorophyll.