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Carbohydrates and Nucleic Acids
Published in Michael B. Smith, A Q&A Approach to Organic Chemistry, 2020
Mutarotation is the equilibrium between the α- to the β-anomers of a carbohydrate. The equilibrium is established for a carbohydrate when dissolved in water that involves the α- and the β-anomers as well as the open-chain aldehyde form change, accompanied by a change in specific rotation. This equilibrium is established when the hemiacetal form of a carbohydrate changes the configuration of the O—CHOH group from C1-R to C1-S (or from C1-S to C1-R). The specific rotation will change to reflect the equilibrium mixture. What properties of a sugar such as glucose lead to mutarotation?
Crystalline fructose production: a conceptual design with experimental data and operating cost analysis
Published in Chemical Engineering Communications, 2022
C. E. Crestani, A. T. C. R Silva, A. Bernardo, C. B. B. Costa, M. Giulietti
Several studies in the literature (Jayasuryiya et al. 1988; Flood et al. 2000) show that crystalline fructose production by crystallization from its aqueous solution is facilitated by the addition of an antisolvent to improve process feasibility, reducing solution viscosity, metastable zone width, its solubility in water (Flood et al. 1996; Gong et al. 2011; Crestani et al. 2013) and, consequently, increasing crystallization yields. Fructose solubility becomes strongly dependent on temperature in solvents highly concentrated in ethanol, increasing yields of cooling crystallization (Crestani et al. 2013). Regarding studies on fructose crystallization with ethanol addition, many aspects are focused in the literature, such as the production of fructose crystals from fermentation broth (Jayasuryiya et al. 1988); evaluation of the effects of impurities, including the presence of glucose, in the kinetics of fructose crystallization (Chu et al. 1989); determination of the kinetics of ethanolic crystallization of fructose (Johns et al. 1990); and also the influence of mutarotation of fructose on crystallization and the kinetics of crystallization, by the study of the growth rates and its dependence on the supersaturation of crystallized tautomer (β-D-pyranofructose) (Flood et al. 1996, 2000). In general, the growth rate is proportional to the supersaturation in ethanol/water solvents and lower than the observed in aqueous solutions at the same supersaturation. Giulietti and Bernardo (2012) described interactions between sugar and water and presented a study of water affinity in sugar crystallization. This study showed that the high affinity of sugar and water contributes to the high solubility of sugar and the high viscosity of aqueous solutions of sugars.
An electrocatalyst for detection of glucose in human blood: synergy in Pd–AuNPs/GOx/C surfaces
Published in Chemical Engineering Communications, 2019
Hilal Celik Kazici, Muge Yayla
All chemicals used in this study namely GOx, EC 1.1.3.4 from Aspergillus niger, 100 U mg−1), bovine serum albumin (BSA > 98%), Nafion (5% wt), glutaraldehyde (50% solution), carbon, and metal precursors (K2PdCl4 and AuCl3) were purchased from Sigma–Aldrich. 0.1 M phosphate buffer (PB) solution was prepared from K2HPO4 and KH2PO4 (Sigma–Aldrich), the pH was adjusted to 7.0. Glucose stock solution was kept at least 24 h after preparation for mutarotation.
A novel electrochemical glucose biosensor based on a poly (L-aspartic acid)-modified carbon-paste electrode
Published in Preparative Biochemistry & Biotechnology, 2020
The graphite powder was obtained from Merck, while the GOx (derived from Aspergillus Niger) was purchased from Sigma. The other chemicals used in the experiments were also purchased from Sigma. The glucose stock solution was left for 24 hr for mutarotation proposes prior to use in order to reach a stable ratio of the α and β forms of the D-(+)-glucose. All the experiments were conducted at room temperature. Double distilled water was used for all the experiments.