Structural adaption in living systems is achieved by competing catalytic pathways that drive assembly and disassembly of molecular components under the influence of chemical fuels. We report on a ...simple mimic of such a system that displays transient, sequence‐dependent formation of supramolecular nanostructures based on biocatalytic formation and hydrolysis of self‐assembling tripeptides. The systems are catalyzed by α‐chymotrypsin and driven by hydrolysis of dipeptide aspartyl‐phenylalanine‐methyl ester (the sweetener aspartame, DF‐OMe). We observed switch‐like pathway selection, with the kinetics and consequent lifetime of transient nanostructures controlled by the peptide sequence. In direct competition, kinetic (rather than thermodynamic) component selection is observed.
Off the beaten track: Sequence‐dependent kinetic pathway selection in chemically fueled catalytic self‐assembly of tripeptides is demonstrated, in which the control of the lifetime of the nanostructures is dictated by chemical design. Mimicking the unique features of these systems may open up opportunities to create supramolecular systems for non‐equilibrium motility and shape control.
Rhodotorula glutinis
is capable of synthesizing numerous valuable compounds with a wide industrial usage. Biomass of this yeast constitutes sources of microbiological oils, and the whole pool of ...fatty acids is dominated by oleic, linoleic, and palmitic acid. Due to its composition, the lipids may be useful as a source for the production of the so-called third-generation biodiesel. These yeasts are also capable of synthesizing carotenoids such as β-carotene, torulene, and torularhodin. Due to their health-promoting characteristics, carotenoids are commonly used in the cosmetic, pharmaceutical, and food industries. They are also used as additives in fodders for livestock, fish, and crustaceans. A significant characteristic of
R. glutinis
is its capability to produce numerous enzymes, in particular, phenylalanine ammonia lyase (PAL). This enzyme is used in the food industry in the production of
l
-phenylalanine that constitutes the substrate for the synthesis of aspartame—a sweetener commonly used in the food industry.
•A promising and rapid tool based on FTIR was developed for analyzing sweeteners.•SVM model was indicated as the most effective identification performance.•PLS was constructed to quantify any ...combinations of the five artificial sweeteners.•There is a good agreement between FTIR and HPLC for sweeteners test in beverage.
Fourier transform infrared (FTIR) spectroscopy calibrations were developed to simultaneously determine the multianalytes of five artificial sweeteners, including sodium cyclamate, sucralose, sodium saccharin, acesulfame-K and aspartame. By combining the pretreatment of the spectrum and principal component analysis, 131 feature wavenumbers were extracted from the full spectral range for modelling to qualitative and quantitative analysis. Compared to random forest, k nearest neighbour and linear discriminant analysis, support vector machine model had better predictivity, indicating the most effective identification performance. Furthermore, multivariate calibration models based on partial least squares regression were constructed for quantifying any combinations of the five artificial sweeteners, and validated by prediction data sets. As shown by the good agreement between the proposed method and the reference HPLC for the determination of the sweeteners in beverage samples, a promising and rapid tool based on FTIR spectroscopy, coupled with chemometrics, has been performed to identify and objectively quantify artificial sweeteners.
•Induced new color-taste associations via brief exposure.•Some individuals were better at learning than others.•Preexisting color-taste associations may influence color-taste learning.
Individuals ...can learn to associate tastes with odors through repeated exposure. We adapted this paradigm, testing whether individuals can learn to associate tastes with colors, and whether these learned color-taste associations generalize to unconditioned, but qualitatively similar stimuli. Experiment 1 tested if individuals could learn color-taste associations for prototypical tastes, while Experiment 2 tested if individuals could learn to discriminate specific bitter compounds using color-taste associations. Conditioned stimuli in Experiment 1 consisted of solutions representing four different prototypical taste qualities. Conditioned stimuli in Experiment 2 consisted of three different bitter stimuli and a sucrose control. Both experiments consisted of six laboratory visits. On day 1, participants rated intensities of conditioned and unconditioned stimuli. On days 2–5 participants completed triangle tests, where a color was systematically paired with high/low intensity combinations of the conditioned stimuli. On day 6, participants matched colorless solutions containing the conditioned and unconditioned stimuli to one of four colors in a forced choice task. In Experiment 1, group performance was significantly above chance (25%) when matching the conditioned taste stimulus to the previously paired color. Also, learning generalized to unconditioned stimuli with a similar taste quality. In Experiment 2, group performance versus chance (25%) indicated participants learned associated sweetness with the previously paired color, both for sucrose (conditioned stimulus) and aspartame (unconditioned stimulus). However, matching performance did not exceed chance for the three different bitterants. These data suggest that particular color-taste associations can be learned with repeated exposure, even when the exposure period is relatively brief.
Penelitian ini bertujuan untuk mengetahui pengaruh pemberian aspartam terhadap panjang siklus estrus mencit betina dewasa. Rancangan yang digunakan dalam penelitian ini adalah Rancangan Acak Lengkap ...(RAL) dengan 4 perlakuan dan 6 ulangan. Perlakuan P0 sebagai kontrol diberi aquades dan perlakuan P1, P2 dan P3 diberi aspartam dosis10 mg/kg bb; 15 mg/kg bb dan20 mg/kg bb. Aspartam diberikan setiap hari secara oral (gavage) selama 14 hari sebanyak 0,3 ml. Setelah 14 hari, apusan vagina dibuat setiap 8 jam dalam sehari selama dua kali siklus estrus. Variabel yang diamati adalah panjang waktu tiap fase dalam siklus estrus. Hasil analisis menggunakan Uji One Way Anova dan Uji Kruskal Wallis menunjukkan bahwa aspartam secara nyata (P<0,05) memperpanjang siklus estrus dengan peningkatan dosis yang diberikan.
For almost 50 years now, biotechnological production processes have been used for industrial production of amino acids. Market development has been particularly dynamic for the flavor-enhancer ...glutamate and the animal feed amino acids L: -lysine, L: -threonine, and L: -tryptophan, which are produced by fermentation processes using high-performance strains of Corynebacterium glutamicum and Escherichia coli from sugar sources such as molasses, sucrose, or glucose. But the market for amino acids in synthesis is also becoming increasingly important, with annual growth rates of 5-7%. The use of enzymes and whole cell biocatalysts has proven particularly valuable in production of both proteinogenic and nonproteinogenic L: -amino acids, D: -amino acids, and enantiomerically pure amino acid derivatives, which are of great interest as building blocks for active ingredients that are applied as pharmaceuticals, cosmetics, and agricultural products. Nutrition and health will continue to be the driving forces for exploiting the potential of microorganisms, and possibly also of suitable plants, to arrive at even more efficient processes for amino acid production.
Three stochastic sensors based on nanodiamond (nDP) paste modified with α, β, and γ‐cyclodextrin were designed and characterized for pattern recognition of aspartame, acesulfame K and sodium ...cyclamate in beverages, ketchup, and biological fluids. The linear concentration ranges obtained for acesulfame K (between 1.00×10−10 mol L−1and 1.00×10−3 mol L−1), for aspartame (between 1.00×10−12 mol L−1 and 1.00×10−3 mol L−1) and for sodium cyclamate (between 4.97×10−12 mol L−1 and 4.97×10−3 mol L−1) allow their assay in biological fluids, beverages and ketchup. The lowest limits of quantification were obtained using the stochastic sensor based on γ‐CD/nDP: for acesulfame K 1.00×10−10 mol L−1, for aspartame 1.00×10−12 mol L−1 and for sodium cyclamate 4.97×10−12 mol L−1. All three stochastic sensors revealed very high values of sensitivities. The proposed method was reliable for qualitative and quantitative assay of aspartame, acesulfame K and sodium cyclamate in beverages, ketchup, and in biological fluids such as urine.
Adult male and female mosquitoes consume sugar as floral and extrafloral nectar. Earlier work demonstrated that mosquito populations and their vector potential are dependent upon the availability of ...sugar sources. Thus, a novel method of vector control may involve targeting sugar-feeding mosquitoes. Multiple human-safe sugar substitutes are already approved by the U.S. Food and Drug Administration and are readily available. However, plant-based sugar substitutes such as stevia (erythritol) have been shown to affect lifespan in other flies. Therefore, the current study was carried out to test the potential of commercially available sugar substitutes to adversely affect the survival, fecundity, and metabolism of adult Aedes aegypti mosquitoes. Of the four sugar substitutes tested, erythritol (Stevia), sucralose (Splenda), aspartame (Equal), and saccharin (Sweet'N Low), only erythritol negatively affected mosquito longevity and fecundity. The effect on fecundity was probably due in part to a corresponding decrease in glycogen and lipid levels over time in mosquitoes fed on erythritol. Comparative mosquito head transcriptomes indicated upregulation of a gene in the mannose biosynthesis pathway in females fed on erythritol, suggesting that N-linked glycosylation might be responsible for the negative impact of erythritol feeding in mosquitoes. Mosquitoes preferred sucrose when a choice was given but were not averse to erythritol. Our results suggest the possibility of using erythritol alone or in combination with sucrose as a component of attractive toxic sugar baits for a human-safe approach for mosquito control.
Estimated intake of six low and no-calorie sweeteners (LNCS) (acesulfame potassium, aspartame, cyclamate, saccharin, steviol glycosides and sucralose) from processed foods and beverages, as well as ...from tabletop sweeteners uses, by the Brazilian population were derived and compared to the respective Acceptable Daily Intake (ADI). The estimates were based on dietary consumption data from a nationwide cross-sectional survey conducted by the Instituto Brasileiro de Geografia e Estatística (IBGE) in 2008-2009 and LNCS use rates and associated market share information based on data provided by Brazilian industry members. Two intake scenarios were considered: a conservative brand loyal consumer scenario that assumes all LNCS-containing foods and beverages and tabletop sweeteners contain the maximum reported LNCS concentrations (Scenario A) and a scenario representative of the general consumer population that uses a market share weighted average of the reported concentrations (Scenario B). Intake estimates were derived for the total Brazilian population (age 10 + y), and for the subpopulations of adolescents (10-18y), adults (19-59y), and older adults (60 + y). Intake of LNCS up to the 95
th
percentile did not exceed their respective ADI for all subpopulations considered, in either the general consumer scenario or the brand loyal scenario. Among consumers age 10 + y, the 95
th
percentile intakes of the various LNCS ranged from 6.8% to 54% of their respective ADI for the brand loyal scenario and from <1% to 6.0% of their respective ADIs for the general consumer scenario.
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