Characterization of Poly(ethylene glycol)-Modified Superoxide Dismutase: Comparison of Capillary Electrophoresis and Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry
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The poly(ethylene glycol) (PEG)-modified enzyme superoxide dismutase (PEG-SOD) was characterized using capillary electrophoresis (CE), and the results were compared to those obtained using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. A free-solution CE method was developed which separated PEG-SOD species based on the number of attached PEG chains. The identity of individual CE peaks was established by isolation and subsequent molecular weight analysis by MALDI. The accuracy of the CE method in determining the average total number of PEG chains attached to the enzyme was established by comparing it with an HPLC method that quantitates the amount of PEG after hydrolytic cleavage from the modified enzyme. In addition to determining the average number of PEG chains attached to the protein, the CE method provides information on the distribution of PEG conjugation to the SOD. The total amount and distribution of coupling of PEG to the enzyme was also directly measured using MALDI. The distribution profile of PEG modification for a typical sample of PEG-SOD as determined by CE was found to be consistent with that obtained by MALDI. A quantitative comparison of the results obtained by the two techniques on PEG-SOD samples representing a range of values of PEG modification of the enzyme demonstrated good correlation, although differences were noted in some cases. Both techniques achieved a high degree of reproducibility when properly optimized. Data were also obtained on stressed samples of PEG-SOD demonstrating the ability of the CE method to detect changes in the degree and distribution of PEG conjugation for samples on stability. These two techniques provide a convenient means of characterizing the distribution of coupling of PEG to this enzyme which may have applications to other PEG modified proteins.Cite
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Abstract Pure samples of the oligo(ethylene glycol)s 1a ( n = 30 or 45), were prepared from the monosodium salt ( 1c ) and the ditosylate ( 1b ) of pentadeca(ethylene glycol). The Melting points of the samples were found to be higher than those of comparable materials prepared hitherto. The melting points of several pure oligo(ethylene glycol)s in the range n = 9 to 45, deriving from this and earlier work, were compared with those of commercially available poly(ethylene glycol)s of similar average chain lengths.
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Fe3+とM2+(M=Ni,Cu,Co,Zn)を含む複シュウ酸塩を,金属硝酸塩水和物のポリエチレングリコール(以後PEGと略す)溶液を353 K,3h加熱処理することで調製した。シュウ酸塩は,PEG溶液中のPEG-陽イオン複合体が硝酸イオンによって酸化されることで生成した。得られたシュウ酸塩の構造と陽イオン組成は,出発物質であるPEG溶液の組成だけでなく,PEG分子量にも依存した。PEG分子量の増加により,得られたシュウ酸塩の結晶化度や粒子の大きさが増大した。これらの事実を理解するためにPEG溶液中のPEG-陽イオン複合体の生成過程について二つのモデルを検討した。それらは,Fe3+とM2+のPEGへの配位が独立に起こると仮定するものと協同的に起こると仮定するものである。これらのモデルを用いてPEG溶液の陽イオン組成と得られたシュウ酸塩の陽イオン組成の間の関係式を導いた。モデルから導かれた関係と実験結果を比較した結果,Fe3+がPEGに配位するとき,その近傍で常にM2+のPEGへの配位が起こることがわかった。
PEG 400
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A review is given on application of electrochemiluminescence(ECL) of Ru(bpy)2+3 subjected to capillary electrophoresis in pharmaceutical analysis,food analysis,and bioscience.The basic characteristics of ECL of Ru(bpy)2+3 subjected to capillary electrophoresis are briefed,and development in the applied research on ECL of Ru(bpy)2+3 subjected to capillary electrophoresis and combined with composites and microchip is introduced.Moreover,suggests are provided about the prospects of ECL of Ru(bpy)2+3 subjected to capillary electrophoresis.
Electrochemiluminescence
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Abstract Capillary electrophoresis and the use of electrochemically based detection schemes for capillary electrophoresis are reviewed. The three different electrochemical methods used in capillary electrophoresis include potentiometric, conductivity, and amperometric detection.
Amperometry
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The efficient conversion of biomass-derived glycolide into ethylene glycol over CuO in water was investigated. After the optimized reaction conditions, the reaction of glycolide was carried out with 25 mmol Zn and 6 mmol CuO with 25% water filling at 250 °C for 150 min, which yielded the desired ethylene glycol at 94% yield. In this work, water acted not only as an excellent environmentally benign reaction medium but also as a hydrogen source. A possible reaction pathway for the in situ hydrogenation of bio-based glycolide into ethylene glycol was proposed. The study provided a green process for the efficient formation of ethylene glycol from biomass-derived glycolide without the use of gaseous hydrogen.
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In this paper, the conversion of biomass-derived glycolide to ethylene glycol over Cu was investigated. As a result, Cu showed significant catalytic role for the conversion of glycolide into ethylene glycol compared to other catalysts, such as Ni and Mo. A 24.3% yield of ethylene glycol was achieved in the process. The possible formation pathway of ethylene glycol from glycolide over Cu under hydrothermal conditions was proposed.
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We have studied the water treatment by pulsed power discharge in water droplets spray in air. Ethylene glycol was used for sample. The dependence of decomposition of ethylene glycol on initial concentration was investigated. It was found that intermediate product was generated by decomposing process of ethylene glycol. In the concentration of 50 mg/L, whole ethylene glycol was decomposed by water treatment for 4 hours. However whole intermediate product wasn't decomposed in 4 hours treatment. In the concentration of 25 mg/L, ethylene glycol and intermediate product were decomposed in treatment time at 4 hours.
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Poly(ethylene) glycol monomethyl ethers (Peg-mmes) are a series of methyl substituted poly(ethylene) glycols that have been used with some success in the crystallization of a number of hydrophobic proteins. Crystallization of a lipase from Humicola lanuginosa complexed with the C12 substrate analogue from Peg-mme 5000, an endoglucanase 1 and a 59 kDa fragment of human topoisomerase IIalpha crystallized from Peg-mme are described. The use of Peg-mme for improving the quality of crystals previously grown from normal poly(ethylene) glycol 8000 is also described. We suggest that these modified Peg-mmes should be regularly used in screening for crystallization.
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Capillary electrophoresis–mass spectrometry
Amino Acid Analysis
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