阴离子交换-积分脉冲安培检测法分离测定氨基酸注射液中的氨基酸和葡萄糖

 用阴离子交换 积分脉冲安培检测法测定了氨基酸注射液中 1 7种氨基酸和葡萄糖。研究了氨基酸和葡萄糖在阴离子交换中的保留行为。采用了优化的水、NaOH和NaAc三元梯度淋洗条件。在优化的梯度淋洗条件和积分脉冲安培检测条件下 ,氨基酸和葡萄糖的检出限为 0 3pmol～ 1 0 3pmol,线性范围约为 2个数量级。样品加标回收率为 88 3 %～ 1 0 4 6 %。方法简单、灵敏、准确。     

Direct Bioelectrocatalysis of PQQ‐Dependent Glucose Dehydrogenase

The direct bioelectrocatalysis was demonstrated for pyrroloquinoline quinone‐dependent glucose dehydrogenase (PQQ‐dependent GDH) covalently attached to single‐walled carbon nanotubes (SWNTs). The homogeneous ink‐like SWNT suspension was used for both creating the SWNT network on the microelectrode carbon surface and for enzyme immobilization. Functionalization of the SWNT surface by forming active ester groups was found to considerably enhance SWNT solubility in water with a range from 0.1 to 1.0 mg/mL. The PQQ‐dependent GDH immobilized on the surface of the SWNTs exhibited fast heterogeneous electron transfer with a rate constant of 3.6 s^?1. Moreover, the immobilized PQQ‐dependent GDH retained its enzymatic activity for glucose oxidation. A fusion of PQQ‐dependent GDH with SWNTs has a great potential for the development of low‐cost and reagentless glucose sensors and biofuel cells.     

Resolution of 8-aminonaphthalene-1,3,6-trisulfonic acid-labeled glucose oligomers in polyacrylamide gel electrophoresis at low gel concentration

A discontinuous Tris-Cl/acetate (OAc) buffer system, unprecedently containing OAc as the trailing constituent, and operative in polyacrylamide gel electrophoresis (PAGE) at low polyacrylamide concentration (T = 4.8%) is described in the paper. The characteristics of the electrophoretic system are illustrated by the resolution of fluorescent 8-aminonaphthalene-1,3,6-trisulfonic acid (ANTS)-labeled malto-oligosaccharides and dextran homopolymers. In this buffer system, the resolving phase is constituted by Tris-OAc behind a moving boundary formed between the leading chloride ion of Tris-HCl gel buffer and the trailing OAc ion provided by a catholyte of NH(4)OAc. In contrast with the results obtained with Tris-CI/glycinate buffer commonly used in electrophoresis, or with Tris-CI/borate, the best resolution of the glucose oligomers containing 1-4 glucose units in Tris-OAc, pH 8.8, ionic strength of 0.08, was obtained at 4.8% polyacrylamide concentration, using 0.5 M NH(4)OAc, pH 9.5 as the catholyte. Under those conditions, the ANTS-glucose oligomers were separated with mobilities decreasing from glucose to maltohexaose. The linear Ferguson plots (log relative mobility, R(f), vs.%T) of the glucose oligomers show that the surface net charge of those oligomers is inversely related to their sizes, given by the slopes, K(R), of the plots. The molecular weight of the oligomers is directly but nonlinearly related to K(R). The novel electrophoretic system illustrated here for separation of short ANTS-saccharides can be potentially applied to the resolution of other biomolecules such as rapidly migrating DNA, peptides or proteins.     

Volumetric properties of glucose in aqueous HCl solutions at temperatures from 278.15 to 318.15 K

Densities have been measured for Glucose + HCl +Water at 10-degree intervals from 278.15 to 318.15 K. The apparent molar volumes (V _Φ,G) and standard partial molar volumes (V _Φ,G ⁰ ) for Glucose in aqueous solution of 0.2, 0.4, 0.7, 1.1, 1.6, 2.1 mol·kg⁻¹ HCl have been calculated as well as volumetric interaction parameters (V _EG) for Glucose — HCl in water and standard partial molar expansion coefficients (∂V _Φ,G ⁰ / ∂T)_p. Results show that (1) the apparent molar volume for Glucose in aqueous HCl solutions increases lineally with increasing molality of Glucose and HCl; (2) V _Φ,G/0 for Glucose in aqueous HCl solutions increases lineally with increasing molality of HCl; (3) the volumetric interaction parameters for Glucose — HCl pair in water are small positive and vary slightly with temperature; (4) the relation between V _Φ,G ⁰ and temperature exists as V _Φ,G ⁰ = a ₀ + a ₁(T − 273.15 K)^2/3; (5) values of (∂V _Φ,G ⁰ / ∂T)_p are positive and increase as temperatures rise, and at given temperatures decrease slightly with increasing molalities of HCl, indicating that the hydration of glucose decreases with increasing temperature and molality of HCl. These phenomena are interpreted successfully by the structure interaction model. Translated from Acta Chimica Sinica, 2006, 64(16): 1635–1641 (in Chinese)     

Biosensing Membrane Base on Ferulic Acid and Glucose Oxidase for an Amperometric Glucose Biosensor

A biosensing membrane base on ferulic acid and glucose oxidase is synthesized onto a carbon paste electrode by electropolymerization via cyclic voltammetry in aqueous media at neutral pH at a single step. The developed biosensors exhibit a linear response from 0.082 to 34 mM glucose concentration, with a coefficient of determination R² equal to 0.997. The biosensors display a sensitivity of 1.1 μAmM⁻¹ cm⁻², a detection limit of 0.025 mM, and 0.082 mM as glucose quantification limit. The studies reveal stable, repeatable, and reproducible biosensors response. The results indicate that the novel poly-ferulic acid membrane synthesized by electropolymerization is a promising method for glucose oxidase immobilization towards the development of glucose biosensors. The developed glucose biosensors exhibit a broader linear glucose response than other polymer-based glucose biosensors.     

Structure of an anthocyanin-anthocyanin dimer molecule in anthocyanin-producing cells of a carrot suspension culture

A novel anthocyanin, an anthocyanin-anthocyanin dimer, was isolated from the cells of an anthocyanin-producing carrot cell-line culture, and its structure was elucidated using spectroscopic methods. It consists of two molecules of the anthocyanin, cyanidin 3-[xylosyl-(sinapoyl-glucosyl)-galactoside], with a CH-CH₃ linkage at the 8-8 position. This is the first report of the identification and isolation of an anthocyanin-anthocyanin dimer with a CH-CH₃ linkage from intact plant cells.     

In situ proton NMR study of acetyl and formyl group migration in mono‐O‐acyl D‐glucose

Acetyl and formyl group migration, mutarotation, and hydrolysis of mono‐O‐acylated glucose are studied by in situ 1D and 2D ¹H NMR spectroscopy. α‐D ‐Glucosyl‐1‐acetate and α‐D ‐glucosyl‐1‐formate serve as sole starting materials. They are generated in situ by configuration retaining glucosyltransfer from α‐D ‐glucosyl‐1‐phosphate to formate and acetate, which is catalyzed by the Glu‐237 → Gln mutant of Leuconostoc mesenteroides sucrose phosphorylase. Temporary accumulated regio‐isomeric mono‐O‐acyl D ‐glucoses are identified, characterized, and quantified directly from the reaction mixture. Time courses of the transformations give insight into pH dependence of acyl group migration and mutarotation as well as into the stability of various regioisomers. Copyright © 2009 John Wiley & Sons, Ltd.