Hydrolytic and chromatographic studies on the PEGylation of dextranase from Penicillium sp.

AbstractDextranases catalyze the hydrolysis of the α-l,6-glucosidic bond of the polysaccharide dextran. Dextranases have been isolated from bacteria, yeast and fungi. Purified dextranase enzyme from Penicillium sp. was PEGylated (polyethylene glycol modification) with mPEG (5000Da) and showed an increase in the dextranase protein molecular weight as estimated by Superose 12 (23ml) column and this increment in the molecular weight is directly proportional to mPEG (5000Da) concentration until a complete dextranase enzyme PEGylation (disappearance of dextranase peak). The residual activity of partially PEGylated dextranase (mPEG 5000 of 5.8mg/ml) was 33.8% and for the completely PEGylated dextranase (mPEG 5000 of 29mg/ml) it was 25.75%. Dextranase PEGylated with mPEG (30,000Da) showed a little PEGylation at mPEG concentration of 5.8mg/ml but at a concentration of 29mg/ml several PEGylated peaks were produced with a difference in dextranase activity toward dextran T500, retardation in the activity with the increasing in the molecular weight was clearly appeared with Sephadex G75 but for Sephadex G200 a little retardation than Sephadex G75 has been appeared

LARGE-SCALE CHROMATOGRAPHY

The physical phenomena occurring in operating large chromatography columns are discussed on both a molecular and macroscopic level. The problems connected with the use of macroporous gel materials for the fractionation of biological macromolecules are briefly discussed

Urea gradient size-exclusion chromatography enhanced the yield of lysozyme refolding

Protein refolding is still a bottleneck for large-scale production of valuable proteins expressed as inclusion bodies in Escherichia coli. Usually biologically active proteins cannot be obtained with high yield at a high concentration after refolding. In order to meet the challenge of protein refolding a urea gradient gel filtration-refolding system was developed in this article. A Superdex 75 column was pre-equilibrated with a linear decreased urea gradient, the denatured protein experienced the gradual decrease in urea concentration as it went through the column. The refolding of denatured lysozyme showed this method could significantly increase the activity recovery of denatured lysozyme at high protein concentration. The activity recovery of 90% was obtained from the initial protein concentration up to 17 mg/ml within 40 min

蛋白质在层析过程中的失活与复性

在层析分离过程中 ,层析的固相介质和溶液环境会引起蛋白质的结构变化 :天然的蛋白质可能会降低活性甚至完全失去活性 ,而结构变化了的蛋白质也可能重新折叠恢复活性 .此类现象已经引起研究者特别是生化工程学家的关注 ,层析介质的种类和操作手段是影响此两个过程的关键因素 .利用不同的层析方法 ,对不同的蛋白质采取相应的措施有利于提高活性蛋白质的回收率 ,具有重要的理论和应用价值

混合模式吸附色谱分离纯化贻贝粘蛋白的研究

[目的]研究高强度琼脂糖基质混合模式吸附介质分离纯化贻贝粘蛋白的方法并探讨分离机理。[方法]考察在不同酸碱度、不同离子强度下,贻贝粘蛋白在凝胶上的静态吸附、动态吸附及解吸附过程。[结果]氯化钠浓度从0增加到0.5mol/L,介质和蛋白之间平衡吸附量变化在6%以内;而酸碱度对吸附的影响较大,当酸碱度跨越蛋白等电点时,单位酸碱度(pH)最大吸附量变化百分比达23%。[结论]介质的复合配基与贻贝粘蛋白间表现了离子交换、疏水作用、氢键吸附的混合吸附作用,采用酸碱度高于等电点的洗脱液洗脱贻贝粘蛋白,得到纯度为90%的贻贝粘蛋白

Rapid two-step purification of a recombinant mouse Fab fragment expressed in Escherichia coli

We report a rapid, large-scale process for the purification of a recombinant Fab fragment specific for the tobacco mosaic virus coat protein (Fab57P). The fragment is expressed periplasmically in Escherichia coli. The expression level was optimized in 0.3-L fermentors. The highest levels were obtained using the following conditions: (1) low postinduction temperature (21 degrees C), (2) combined use of two beta-lactam antibiotics (carbenicillin and ampicillin), (3) IPTG concentration 0.1 mM, (4) regulated pH 7.2, (5) 17-h induction time, and (6) conditions that reduce mechanical stress. Optimized large-scale fermentations were done in 15- and 300-L capacity fermentors. The recombinant Fab fragment was purified by two chromatographic steps. After disruption of the bacteria using an APV Gaulin homogenizer, the crude E. coli homogenate was directly applied, without centrifugation, to an SP Sepharose Big Beads column. The recombinant Fab fragment was eluted as a single peak in a sodium chloride gradient. The fragment was further purified by affinity adsorption to a column packed with Epoxy-activated Sepharose 6B to which the antigen peptide NH(2)-CGS YNR GSF SQS SGLV-CONH(2) had been coupled through its N-terminal cysteine. The purified Fab57P fragment showed one band in SDS-PAGE. The overall purification yield was 35%

Biotechnol. J.

Following its market introduction in 1982, the cross-linked 12% agarose gel media Superose 12 has become widely known as a tool for size exclusion chromatography of proteins and other biological macromolecules. In this review it is shown that, when appropriate mobile phases are used, Superose possesses adsorption properties similar to that of traditional media for hydrophilic interaction liquid chromatography (HILIC). This is illustrated by the separation and purification of low molecular weight compounds such as polyphenols including active components of traditional Chinese medicinal herbs and green tea. Structural features of the cross-linked agarose that likely cause the observed adsorption effects are discussed aswell. These are identified as being primarily ether bonds acting as strong hydrogen bond acceptors as well as hydrophobic residues originating from the cross-linking reagents.Following its market introduction in 1982, the cross-linked 12% agarose gel media Superose 12 has become widely known as a tool for size exclusion chromatography of proteins and other biological macromolecules. In this review it is shown that, when appropriate mobile phases are used, Superose possesses adsorption properties similar to that of traditional media for hydrophilic interaction liquid chromatography (HILIC). This is illustrated by the separation and purification of low molecular weight compounds such as polyphenols including active components of traditional Chinese medicinal herbs and green tea. Structural features of the cross-linked agarose that likely cause the observed adsorption effects are discussed aswell. These are identified as being primarily ether bonds acting as strong hydrogen bond acceptors as well as hydrophobic residues originating from the cross-linking reagents