Development of a novel analytical method for determination of chondroitin sulfate using an in-capillary enzyme reaction

Plug-plug kinetic capillary electrophoresis for in-capillary exoglycosidase digestion as a profiling tool for the analysis of glycoprotein glycans

An online exoglycosidase digestion was combined with a plug-plug kinetic mode of capillary electrophoresis (CE) for the analysis of glycoprotein-derived oligosaccharides. An exoglycosidase solution and a solution of glycoprotein glycans derivatized with 8-aminopyrene-1,3,6-trisulfonic acid (APTS) were introduced to a neutrally coated capillary previously filled with electrophoresis buffer solution containing 0.5w/v% hydroxypropylcellulose. After immersion of both ends of the capillary in the buffer solutions, a negative voltage was applied for analysis. An APTS group of an oligosaccharide derivative has triply negative charges, which forced saccharide derivatives to anode with fast mobility and pass through the enzyme plug, which are detected at the anodic end. If the terminal monosaccharides of APTS-labeled oligosaccharides are released by the action of an exoglycosidase, the migration times of the oligosaccharides shift to those of digested oligosaccharides. We examined β-galactosidase, α-mannosidase, β-N-acetylhexosaminidase, α-neuraminidase, and α-fucosidase, and found only β-galactosidase and α-neuraminidase showed good reactivity toward APTS-labeled oligosaccharides; the reaction was completed by injecting a 3.6cm long plug of 200 and 50mU/mL concentration of exoglycosidases. In contrast, other exoglycosidases could not react with APTS labeled oligosaccharides at a concentration up to 5U/mL. The β-N-acetylhexosaminidase reaction was successively followed by the electrophoretic mobility of APTS oligosaccharides and stopped for 10min when saccharide derivatives were achieved in the enzyme plug. The reaction of α-fucosidase and α-mannosidase was completed by decreasing the electrophoretic voltage to -2kV when the APTS oligosaccharides were passing through an exoglycosidase plug. We established the CE conditions for all of the glycosidic linkage analysis of glycoprotein glycans.

Analysis of chondroitin sulfate from different sources of cartilage by electrophoretically mediated microanalysis

An electrophoretically mediated microanalysis protocol for the determination of different chondroitin sulfate origins was developed.

A dual-wavelength overlapping resonance Rayleigh scattering method for the determination of chondroitin sulfate with nile blue sulfate

A dual-wavelength overlapping resonance Rayleigh scattering (DWO-RRS) method was developed to detect chondroitin sulfate (CS) with nile blue sulfate (NBS). At pH 3.0-4.0 Britton-Robinson (BR) buffer medium, CS interacted with NBS to form an ion-association complex. As a result, the new spectra of resonance Rayleigh scattering (RRS), second order scattering (SOS) and frequence doubling scattering (FDS) appeared and their intensities were enhanced greatly. Their maximum wavelengths were located at 303 nm (RRS), 362 nm (RRS), 588 nm (SOS) and 350 nm (FDS), respectively. The scattering intensities of the three methods were proportional to the concentration of CS in certain ranges. The methods had high sensitivity and the detection limits were between 1.5 and 7.1 ng mL(-1). The DWO-RRS method had the highest sensitivity with the detection limit being 1.5 ng mL(-1). The characteristics of the spectra and optimal reaction conditions of RRS method were investigated. The effects of coexistent substances on the determination of CS were evaluated. Owing to the high sensitivity, RRS method had been applied to the determination of CS in eye drops with satisfactory results. The recovery range was between 99.4% and 104.6% and the relative standard deviation (RSD) was between 0.4% and 0.8%. In addition, the reasons for RRS enhancement were discussed and the shape of ion-association complex was characterized by atomic force microscopy (AFM).

Highly sensitive and surface-renewable electrochemical quartz crystal microbalance assays of heparin and chondroitin sulfate based on their effects on the electrodeposition of neutral red

The electrochemical quartz crystal microbalance (EQCM) technique was used to investigate the electrochemistry of neutral red (NR) in phosphate buffer solution (PBS) and the effects of coexisting heparin (Hep) or chondroitin sulfate (CS) for the first time. The pH dependence of the electrochemistry of NR was examined, and a V-shaped frequency response (versus time) was observed during the cyclic voltammetric experiment of NR in a nearly neutral medium (pH ca. 6.10-7.00), being due to the electrodeposition and stripping of the poorly soluble reduced product of NR (NR(Red)) at these pH values. The effects of potential scan rate, the concentration of NR, and several supporting electrolytes were examined at pH 6.80. The V-shaped response to the redox switching of NR was weakened by the introduction of Hep or CS, being due to the increased inhibition of the NR(Red) electrodeposition probably via the electrostatic interaction of the NR and especially the NR(Red) with Hep or CS. The height of the V-shaped response decreases with the increase of Hep or CS concentration, with limits of detection down to 3 nmol L(-1) for Hep and 2 nmol L(-1) for CS, respectively. The novel and surface-regenerable EQCM assay protocol based on the electrochemically switchable deposition of a dye is highly recommended for wide biosensing applications.

Enzymatic in-capillary derivatization for glucose determination by electrophoresis with spectrophotometric detection

The following paper compares several procedures of in-capillary bienzymatic derivatization with regard to glucose determination with the use of glucose oxidase and horseradish peroxidase. The procedures discussed below include continuous contact in the capillary, plug-plug injection, and sequential injection with incubation in the capillary inlet. The reaction of hydrogen peroxide catalyzed by peroxidase was performed using two different substrates. The best results were achieved for nicotinamide adenine dinucleotide, reduced disodium salt (NADH) acting both as a chromogenic reagent and a substrate for peroxidase, while the method employed was sequential injection and incubation at the capillary inlet. The LOD was estimated to be 25 nM with a linear response up to 0.1 microM.

Capillary electrophoresis of complex natural polysaccharides

Complex natural polysaccharides, glycosaminoglycans (GAGs), are a class of ubiquitous macromolecules that exhibit a wide range of biological functions and participate and regulate multiple cellular events and (patho)physiological processes. They are generally present either as free chains (hyaluronic acid and bacterial acidic polysaccharides) or as side chains of proteoglycans (PGs; chondroitin/dermatan sulfate, heparin/heparan sulfate, and keratan sulfate) and are most often found in cell membranes and in the extracellular matrix. The recent emergence of modern analytical tools for their study has produced a virtual explosion in the field of glycomics. CE, due to its high resolving power and sensitivity, has been useful in the analysis of intact GAGs and GAG-derived oligosaccharides and disaccharides affording concentration and structural characterization data essential for understanding the biological functions of GAGs. In this review, novel off-line and on-line CE-MS and MS/MS methods for screening of GAG-derived oligosaccharides and disaccharides will be discussed.

Capillary electrophoresis for the quality control of chondroitin sulfates in raw materials and formulations

Exogenous administration of chondroitin sulfate (CS) is widely practiced for the treatment of osteoarthritis, although the efficacy of this treatment has not been completely established by clinical studies. A reason for the inconsistency of the results may be the quality of the CS preparations, which are commercially available as dietary supplements. In this article, we describe the development of a new method of capillary electrophoresis (CE) for the quantification of CS concentrations, screening for other glycosaminoglycan or DNA impurities and determination of hyaluronan impurities in CS raw materials, tablets, hard capsules, and liquid formulations. Analysis is performed within 12 min in bare fused silica capillaries using reversed polarity and an operating phosphate buffer of low pH. The method has high sensitivity (lower limit of quantitation [LLOQ] values of 30.0 microg/ml for CS and 5.0 microg/ml for hyaluronan), high precision, and accuracy. Analysis of 11 commercially available products showed the presence of hyaluronan impurities in most of them (up to 1.5%). CE analysis of the samples after treatment with chondroitinase ABC and ACII, which depolymerize the chains to unsaturated disaccharides, with a previously described method (Karamanos et al., J. Chromatogr. A 696 (1995) 295-305) confirmed the results of hyaluronan determination and showed that the structural characteristics (i.e., disaccharide composition) of CS are very different, showing the different species or tissue origin and possibly affecting the therapeutic outcome.

Determination of cyanide in microliter samples by capillary electrophoresis and in-capillary enzymatic reaction with rhodanese

This paper describes a method for the determination of cyanide using in-capillary enzymatic reaction with rhodanese. Poorly absorbing cyanide is in rhodanese reaction transformed into highly absorbing thiocyanate that is further separated by capillary electrophoresis (CE) and determined spectrophotometrically at 200 nm. Cyanide is thus estimated indirectly from the result of thiocyanate quantification and moreover, it can be easily determined with sufficient sensitivity by means of CE apparatus equipped with common UV detector. The linear detection range for concentration versus peak area for the assay is from 15 to 500 microM (correlation coefficient 0.997) with a detection limit of 3 microM and a limit of quantitation 9 microM. The inter-day reproducibility of the peak area was below 3.2% and the inter-day reproducibility of the migration time below 0.1%. The method is relatively rapid, simple and can be easily automated. Moreover, only limited amount of the sample is required.

Micellar electrokinetic capillary chromatography--synchronous monitoring of substrate and products in the myrosinase catalysed hydrolysis of glucosinolates

A micellar electrokinetic capillary chromatography (MECC) method has been developed for monitoring the myrosinase catalysed hydrolysis of 2-hydroxy substituted glucosinolates and the simultaneous formation of the corresponding degradation products (oxazolidine-2-thiones (OZTs) and nitriles). Glucosibarin ((2R)-2-hydroxy-2-phenylethylglucosinolate) was chosen as the model glucosinolate owing to the difficulties in determining hydrolysis rates of this type of substrates in traditional UV-assays. The method was afterwards validated with glucobarbarin ((2S)-2-hydroxy-2-phenylethylglucosinolate) and progoitrin ((2R)-2-hydroxybut-3-enylglucosinolate). Aromatic glucosinolates without a 2-hydroxy group in their side chains, such as glucotropaeolin (benzylglucosinolate) and gluconasturtiin (phenethylglucosinolate) were also tested. Formation of the glucosinolate hydrolysis products was monitored simultaneously at 206 nm and 230 nm. This allowed estimation of the extinction coefficient of the OZT derived from glucosibarin, which was found to be 18,000 M(-1) cm(-1) and 12,000 M(-1) cm(-1) at 206 nm and 230 nm, respectively. The developed method has limit of detection of 0.04 mM and 0.06 mM and limit of quantification of 0.2 mM and 0.3 mM for the glucosibarin derived OZT and nitrile, respectively. Linearity of the glucosinolate concentration was examined at six concentration levels from 2.5 mM to 100 mM and at 206 nm a straight line (R(2)=0.9996) was obtained. The number of theoretical plates (N) at the optimal system conditions was 245,000 for the intact glucosibarin, 264,000 for the OZT and 252,000 for the nitrile.

Advances in capillary electrophoretically mediated microanalysis: An update

This review, as a continuation of an earlier report, gives an overview of recent developments, over the period from 2003 until now, in the use of capillary electrophoretic techniques for the in-line study of enzymatic reactions, derivatization, and chemical reactions. The article is divided into two parts: (i) in-line enzymatic reactions and (ii) in-line derivatization and chemical reactions. The first part introduces electrophoretically mediated microanalysis (EMMA) and discusses and illustrates the different modes of EMMA. A literature overview on enzymatic reactions is provided. The second part starts with an introduction of the procedures and the nomenclature used in the area of in-line derivatization and chemical reactions based on EMMA. Reported derivatization and chemical reaction procedures are discussed and summarized.