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Determination of N-glycans in glycoproteins using chemoenzymatic labeling with Endo-M N175Q
Zhang, S.r.,Yu, Y.l.,Xu, C.s.,Jin, D.,Lee, Y.I. Academic Press ; Elsevier Science Ltd 2017 Microchemical journal Vol.130 No.-
A novel approach for the determination of N-glycans in glycoproteins has been developed based on a combination of deglycosylation, chemoenzymatic labeling, and high-performance liquid chromatography/electrospray ionization mass spectrometry (HPLC/ESI-MS). Glycoproteins were digested with PNGase F and then the released N-glycans were enriched and separated from the digesting solution using ultrafiltration units according to the molecular mass differences. The N-glycans were analyzed by HPLC/ESI-MS after chemoenzymatic labeling with Endo-M N175Q an Endo-M mutant. We have shown that the Endo-M N175Q demonstrates a noticeable transglycosidase-like activity for natural N-glycans. The productivity of Endo-M N175Q is estimated to be 2.0-fold higher than that of Endo-M. The experimental strategy was validated using glycoproteins with known glycan structures such as ovalbumin and ribonuclease B. The proposed method offers a promising advance for determining N-glycans in glycoproteins.
An, J.,Lee, J.,Lee, G.,Nam, K.,Yoon, H.O. Academic Press ; Elsevier Science Ltd 2015 Microchemical journal Vol.120 No.-
Feasibility of collision cell (CC) technique with the aid of a methanol modifier for the trace determination of arsenic (As) in a high-chloride-containing sample using ICP-MS was assessed to eliminate the analytical bias induced by polyatomic interference from <SUP>40</SUP>Ar<SUP>35</SUP>Cl<SUP>+</SUP> without decreasing <SUP>75</SUP>As<SUP>+</SUP> intensity, thereby lowering the limit of detection (LOD). The signal intensity of 2% HCl measured at 75m/z was suppressed entirely by introducing He gas into the CC at a flow rate of at least 3mLmin<SUP>-1</SUP>. Results from the calibration experiments revealed that excess He gas in the CC could also decrease the <SUP>75</SUP>As<SUP>+</SUP> intensity. Therefore, an optimized He flow rate should be employed, which seemed to be 3mLmin<SUP>-1</SUP> in this study. To obtain greater sensitivity in the As analysis, the effect of methanol added to the sample solution in varying concentrations (0 to 5% v/v) was assessed. In accordance with previous studies, 3% methanol addition improved As sensitivity by a factor of 2.5 to 3. Also, the methanol addition seemed to decrease the formation of <SUP>40</SUP>Ar<SUP>35</SUP>Cl<SUP>+</SUP>. Overall, the combined use of both strategies with optimized conditions achieved a lower LOD value of 3ngL<SUP>-1</SUP> with a high accuracy.
Kim, Y.H.,Kumar, P.,Kwon, E.E.,Kim, K.H. Academic Press ; Elsevier Science Ltd 2017 Microchemical journal Vol.132 No.-
<P>In this study, formaldehyde (FA) in the air was collected and analyzed using metal-organic framework-5 (MOP-5) as the sorbent material (for both sorbent tube (ST) sampling and thermal desorption (TD) analysis) in gas chromatography-mass spectrometry (GC-MS) detection. A series of experiments was carried out to determine the optimal analytical conditions for maximum recovery of FA by TD-GC-MS. Optimal TD conditions for adsorption and desorption of MOF-5 were determined to be - 25 degrees C and 100 degrees C, respectively. These conditions yielded good linearity (R-2 = 0.9975), precision (mean 1.79 +/- 1.17%), and high sensitivity. The method detection limit (MDL) of 0.1 ng was attained to determine 0.82 ppb of FA in 100 mL of air (limit of detection (LOD) of 8 pg (0.06 ppb)). The concentration of FA, when measured from ambient air samples using MOF-5, averaged 9.67 ppb (n = 3, RSE = 239%). FA samples, when analyzed in parallel using the DNPH cartridge-HPLC-UV system recommended by the US EPA, yielded similar results (mean of 10.5 ppb) to the MOF-5 dataset In addition, trace quantities of FA (0.25 ng) were also detected from samples of as little as 20 mL of air. Our results suggest that MOF-5 is a suitable sorbent media for thermal desorption analysis and in fact surpasses the performance of commercial sorbents used for VOC analysis. As such, a GC-based detection method for FA comprising simple thermal desorption without complicated procedures, such as a derivatization step, was realized. (C) 2017 Elsevier B.V. All rights reserved.</P>
Kumar, P.,Kim, K.H.,Bansal, V.,Paul, A.K.,Deep, A. Academic Press ; Elsevier Science Ltd 2016 Microchemical journal Vol.128 No.-
The feasibility of the nanocrystal metal organic framework [Cd(atc)(H<SUB>2</SUB>O)<SUB>2</SUB>]<SUB>n</SUB> (NMOF1) as a biosensor is explored for the specific recognition of parathion. The luminescence properties of the NMOF1/antiparathion complex were tested for the detection of parathion. Because of the fluorescent properties, the anti-parathion antibody interacted with parathion in order to facilitate its detection at a dynamic concentration range from 1ppb to 1ppm. The assay was validated against some environmental samples by gas chromatography with solid phase extraction (SPE). Accordingly, the NMOF biosensor tested in this work is demonstrated as parathion-specific with high surface loading and high sensitivity.
Probing temperature able to improve Raman spectroscopic discrimination of adulterated olive oils
Ryoo, D.,Hwang, J.,Chung, H. Academic Press ; Elsevier Science Ltd 2017 Microchemical journal Vol.134 No.-
<P>An effective method for improving Raman spectroscopic identification of adulterated extra virgin olive oil (EVOO) was proposed. It was based on probing an optimal sample temperature where the spectral differentiation among components was enhanced, since temperature-induced spectral variations of individual components expected to be diversely different depends on their molecular structures. Initially, oleic and linoleic acids were separately frozen, and Raman spectra were consecutively collected at regular intervals as the temperature increased. The spectral variations of oleic and linoleic acids were dissimilar with each other due the difference in their molecular structures. In the temperature-varied spectra of pure EVOOs and adulterated EVOOs, both the magnitudes and patterns of the spectral differences between the two groups differed, and the measurement at -36.4 degrees C resulted in the lowest discrimination error of 8.0% based on linear discriminant analysis using principal component scores. The spectral features of the two groups became more discernible at this temperature due to the dissimilar temperature-dependent molecular vibrations of the components, which improved the authentication accuracy. (C) 2017 Elsevier B.V. All rights reserved.</P>
Ahn, J.H.,Kim, K.H.,Szulejko, J.E.,Kwon, E.E.,Deep, A. Academic Press ; Elsevier Science Ltd 2016 Microchemical journal Vol.125 No.-
In this research, we investigated the breakthrough volume (BTV) and temporal performance of two types of sorbent tube (ST) sorbent beds toward 10 (target) biogenic volatile organic compounds (BVOCs) ((1) isoprene, (2) (+)-α-pinene, (3) camphene, (4) (+)-β-pinene, (5) (+)-3-carene, (6) α-phellandrene, (7) α-terpinene, (8) ®-(+)-limonene, (9) γ-terpinene, and (10) p-cymene) and two (reference) anthropogenic volatile organic compounds (AVOCs) ((11) benzene and (12) toluene). The analysis of their vaporized liquid-phase working standards was carried out using thermal desorption-gas chromatography-mass spectrometry (TD-GC/MS). To this end, the performance of two ST types (CC (Carbopack C) and CBX (Carbopack C, Carbopack B, and Carbopack X)) was tested as a function of a few key variables, e.g., sorbent type, N<SUB>2</SUB> gas purge volume, and sampling temperature. The CBX ST gave recoveries of 100+/-10% at 60<SUP>o</SUP>C for two BVOCs (camphene and α-terpinene). However, three compounds (isoprene, (+)-α-pinene, and (+)-β-pinene) showed poor recoveries (0.7, 59.3, and 11.3%, respectively), whilst p-cymene recorded an excess recovery (~190%). In contrast, for the CC ST, BT for (+)-α-pinene and camphene increased with purge volume, while isoprene was not detected. Accordingly, the range of BTV<SUB>5%</SUB> and BTV<SUB>50%</SUB> values (L/g) for each compound with CC ST were 1.7 (toluene)-17 (camphene) and 15 (toluene)-570 ((+)-α-pinene), respectively. In summary, a three-bed CBX with the higher BTV is the preferred choice for environmental sampling for a wide range of BVOCs compared to a one-bed CC ST. The recovery of CBX ST for 10 out of 12 analytes (after >150 reconditioning/loading/TD cycles) remained constant in terms of response factor, while the response factors of isoprene and β-pinene were highly variable. Both the present work and the reported literature recoveries showed similar and divergent results which are discussed in terms of high temperature on-sorbent reactions.
Zhang, Z.,Zhang, M.,Wu, X.y.,Chang, Z.,Lee, Y.I.,Huy, B.T.,Sakthivel, K.,Liu, J.f.,Jiang, G.b. Academic Press ; Elsevier Science Ltd 2016 Microchemical journal Vol.124 No.-
A novel homogeneous assay method was put forth for simultaneous sensing of fluoroquinolone derivatives (FQs) in water utilizing the upconversion fluorescence resonance energy transfer (FRET) process based on the competitive reaction between dissolved FQs and labeled AuNPs for FQs Mab connected UCPs. The prepared size-tunable β-NaLuF4:Yb,Er,Gd upconversion phosphors (UCPs) were functionalized with carboxylic acid (COOH-) and monoclonal antibody (Mab, C2F3C2) to act as a donor. The gold nanoparticles (AuNPs) labeled with the corresponding antigen (ciprofloxacin-BSA) take the role of an acceptor. Under optimized conditions, the limit of detections (LODs) for three common FQs, enrofloxacin (ENR), ciprofloxaxin (CIP), and norfloxacin (NOR), were 0.19-0.32ng/mL based on 3σ. The recoveries were found to be in the range of 73.5-114.5% (normalized value according to the cross-reactivity of Mab) for water samples (tap water, pond water and river water). The proposed approach possesses significant advantages as follows: (i) simple procedure (only one step) without washing and separation steps, and no sample pretreatment other than filtration; (ii) fast liquid-phase kinetics with shortened incubation time; and (iii) high tolerance to various interfering substances. All of which indicated its potentiality as an efficient biosensor towards the monitoring of FQs in aquatic environments.