Electrostatic control of thickness and stiffness in a designed protein fiber

Attempts to design peptide-based fibers from first principles test our understanding of protein folding and assembly, and potentially provide routes to new biomaterials. Several groups have presented such designs based on alpha-helical and beta-strand building blocks. A key issue is this area now is engineering and controlling fiber morphology and related properties. Previously, we have reported the design and characterization of a self-assembling peptide fiber (SAF) system based on alpha-helical coiled-coil building blocks. With preceding designs, the SAFs are thickened, highly ordered structures in which many coiled coils are tightly bundled. As a result, the fibers behave as rigid rods. Here we report successful attempts to design new fibers that are thinner and more flexible by further programming at the amino-acid sequence level. This was done by introducing extended, or "smeared", electrostatic networks of arginine and glutamate residues to the surfaces of the coiled-coil building blocks. Furthermore, using arginine--rather than lysine--in these networks plays a major role in the fiber assembly, presumably by facilitating multidentate intra and intercoiled-coil salt bridges.     

Novel Technology Development through Thermal Drying of Encapsulated Kluyveromyces marxianus in Micro- and Nano-tubular Cellulose in Lactose Fermentation and Its Evaluation for Food Production

A novel technology development based on the production of a low-cost starter culture for ripening of cheeses and baking is reported in the present study. The starter culture comprises thermally dried cells of Kluyveromyces marxianus encapsulated in micro- and nano-tubular cellulose. For production of a low-cost and effective biocatalyst, whey was used as raw material for biomass production and thermal drying methods (convective, conventional, and vacuum) were applied and evaluated at drying temperatures ranging from 35 to 60?°C. The effect of drying temperature of biocatalysts on fermentability of lactose and whey was evaluated. Storage stability and suitability of biocatalysts as a commercial starter cultures was also assessed and evaluated. All thermally dried biocatalysts were found to be active in lactose and whey fermentation. In all cases, there was sugar conversion ranging from 92 to 100?%, ethanol concentration of up to 1.47?% (v/v), and lactic acid concentrations ranged from 4.1 to 5.5?g/l. However, convective drying of the encapsulated cells of K. marxianus in micro- and nano-tubular cellulose was faster and a more effective drying method while drying at 42?°C appear to be the best drying temperature in terms of cell activity, ethanol, and lactic acid formation. Storage of the biocatalysts for 3?months at 4?°C proved maintenance of its activity even though fermentation times increased by 50?C100?% compared with the fresh dried ones.     

Scale-up of Thermally Dried Kefir Production as Starter Culture for Hard-Type Cheese Making: An Economic Evaluation

This paper concerns the effect of thermal-drying methodology on the investment cost for dried kefir cells production in order to be used as starter culture in cheese manufacturing. Kefir cells were produced at pilot plant scale using a 250-L bioreactor and whey as the main substrate. Kefir cells were subsequently dried in a thermal dryer at 38?°C and used as a starter culture in industrial-scale production of hard-type cheeses. The use of thermally dried kefir as starter culture accelerated ripening of cheeses by increasing both lipolysis and fermentation rate as indicated by the ethanol, lactic acid, and glycerol formation. Additionally, it reduced coliforms and enterobacteria as ripening proceeded. This constituted the basis of developing an economic study in which industrial-scale production of thermally dried kefir starter culture is discussed. The industrial design involved a three-step process using three bioreactors of 100, 3,000, and 30,000 L for a plant capacity of 300 kg of thermally dried kefir culture per day. The cost of investment was estimated at 238,000 €, which is the 46% of the corresponding cost using freeze-drying methodology. Production cost was estimated at 4.9 €/kg of kefir biomass for a 300-kg/day plant capacity, which is the same as with the corresponding cost of freeze-dried cells. However, the estimated added value is up to 10.8?×?10⁹ € within the European Union.     

Suggestions on the Contribution of Methyl Eugenol and Eugenol to Bay Laurel (Laurus nobilis L.) Essential Oil Preservative Activity through Radical Scavenging

The present study examined the radical scavenging potential of the two benzene derivatives found in the bay laurel essential oil (EO), namely methyl eugenol (MEug) and eugenol (Eug), theoretically and experimentally to make suggestions on their contribution to the EO preservative activity through such a mechanism. Calculation of appropriate molecular indices widely used to characterize chain-breaking antioxidants was carried out in the gas and liquid phases (n-hexane, n-octanol, methanol, water). Experimental evidence was based on the DPPH^• scavenging assay applied to pure compounds and a set of bay laurel EOs chemically characterized with GC-MS/FID. Theoretical calculations suggested that the preservative properties of both compounds could be exerted through a radical scavenging mechanism via hydrogen atom donation. Eug was predicted to be of superior efficiency in line with experimental findings. Pearson correlation and partial least square regression analyses of the EO antioxidant activity values vs. % composition of individual volatiles indicated the positive contribution of both compounds to the radical scavenging activity of bay laurel EOs. Eug, despite its low content in bay laurel EOs, was found to influence the most the radical scavenging activity of the latter.     

Mechanism of Coomassie brilliant blue G-250 binding to proteins: a hydrophobic assay for nanogram quantities of proteins

We investigated the mechanism of Coomassie brilliant blue G-250 (CBB) binding to proteins in order to develop a protein assay with the maximum possible sensitivity. We found that the neutral ionic species of CBB binds to proteins by a combination of hydrophobic interactions and heteropolar bonding with basic amino acids. On the basis of these findings, we developed a very sensitive hydrophobic assay for proteins (at the nanogram level) using the hydrophobic reagents ammonium sulfate and trichloroacetic acid under pH conditions that increase neutral species concentration in the assay reagent in order to enhance the binding of more CBB dye molecules per protein molecule than in previous CBB-based assays.     

Recent Advances on the Anticancer Properties of Saffron (Crocus sativus L.) and Its Major Constituents

Cancer is the second leading cause of death globally with an estimated 9.6 million deaths in 2018 and a sustained rise in its incidence in both developing and developed countries. According to the WHO, about 1 in 6 deaths is due to cancer. Despite the emergence of many pioneer therapeutic options for patients with cancer, their efficacy is still time-limited and noncurative. Thus, continuous intensive screening for superior and safer drugs is still ongoing and has resulted in the detection of the anticancer properties of several phytochemicals. Among the spices, Crocus sativus L. (saffron) and its main constituents, crocin, crocetin, and safranal, have attracted the interest of the scientific community. Pharmacological experiments have established numerous beneficial properties for this brilliant reddish-orange dye derived from the flowers of a humble crocus family species. Studies in cultured human malignant cell lines and animal models have demonstrated the cancer prevention and antitumor activities of saffron and its main ingredients. This review provides an insight into the advances in research on the anticancer properties of saffron and its components, discussing preclinical data, clinical trials, and patents aiming to improve the pharmacological properties of saffron and its major ingredients.     

Modulation of cisplatin cytotoxic activity against leiomyosarcoma cells by epigallocatechin-3-gallate

The aim of this study was to investigate the cytotoxic effect cisplatin in combination with epigallocatechin-3-gallate (EGCG) on leiomyosarcoma cells (LMS cells) in order to identify a less toxic but equally effective alternative. Assays for cell proliferation, colony formation efficiency, induction of apoptosis and cell cycle arrest were performed using the IC₅₀ of cisplatin (8.6 μΜ) as a reference value and a concentration of EGCG (30 μΜ) that caused a non-significant reduction in cell proliferation. Pre-treatment of cells with EGCG for 24 h before the addition of cisplatin increased cytotoxicity up to 8.5% (p < 0.05) and the number of apoptotic cells by 40%. Epigallocatechin-3-gallate failed to alter S-phase cell cycle arrest induced by cisplatin and to modulate cisplatin effects on mitochondrial function. These results indicate that pre-treatment with EGCG could be used as an adjunctive therapy to maximise effectiveness of chemotherapy.     

A Numerical Investigation of the Effects of Fuel Composition on the Minimum Ignition Energy for Homogeneous Biogas-Air Mixtures

Flow, Turbulence and Combustion - The minimum ignition energy (MIE) requirements for ensuring successful thermal runaway and self-sustained flame propagation have been analysed for forced ignition...     

Interference of non-specific peroxidases in the fluorescence detection of superoxide radical by hydroethidine oxidation: a new assay for H<Subscript>2</Subscript>O<Subscript>2</Subscript>

The present study shows that hydroethidine (HE), used for in-vivo qualitative fluorescent detection of superoxide anion, can be also oxidized by H₂O₂ via non-specific peroxidase (horseradish peroxidase and myeloperoxidase) catalysis, forming fluorescent oxidation products. These products give broad excitation/emission peaks (490–495/580–600 nm) near the excitation/emission peaks (475/580 nm) of the HE-superoxide oxidation product, and this may pose serious interference problems to the fluorescent detection of the superoxide radical. The study suggests cautionary use of the HE-superoxide anion assay mainly for detection of reactive oxygen species. A byproduct of this study was the development of a simple and sensitive HE-horseradish peroxidase assay for the in-vitro quantification of H₂O₂ in biological tissues with a sensitivity of 1 mol L^–1.