Polyethylene Glycol Fractionation Research Articles

In vivo evaluation of hyaluronic acid–polyethylene glycol amended PMMA bone cement for orthopaedic application

The utilization of polymethyl methacrylate (PMMA) bone cement is employed for the purpose of stabilizing fractured vertebral bodies. The existence of a mechanical imbalance in hard polymethylmethacrylate (PMMA) bone cement has the potential to increase the likelihood of a fracture occurring in the neighbouring vertebral body. In order to reduce potential difficulties, the primary goal of this study is to investigate the potential benefits of increasing PMMA bone cement’s bioactivity and lowering its elastic modulus. The incorporation of a 10% volume fraction of hyaluronic acid (HyA) and polyethylene glycol (PEG) into the bone cement led to an improvement in the bioactivity and decreasing of elastic modulus of polymethylmethacrylate (PMMA). The integration of HyPE gel phase presents several advantages over pure PMMA bone cement, including enhanced setting parameters, improved degradability, and increased biocompatibility. The gel phase is additionally accountable for a reduction in the elastic modulus of polymethylmethacrylate (PMMA) bone cement. In addition, the existence of a porous structure that arises from the degradation of the HyPE gel phase delivers a significant amount of room, thereby enhancing the process of bone regeneration when implanted in the femur of rabbits. The utilization of HyPE in PMMA has been shown through comprehensive µ-CT analysis to enhance bone formation, thereby promoting osteointegration at the implantation site. Furthermore, the histological analysis demonstrated the existence of osteogenic activity in the PMMA polyethylene glycol supplemented with 10% HyA and 10% PEG after a 2-month period subsequent to implantation.

Improving dispersion of basalt fiber with polyethylene glycol and effect of coupling agent

ABSTRACT Basalt fibers were widely used as reinforcing matrix materials because of their thermal and chemical stability and environmental friendliness. The properties of composite materials were affected by the interaction between the basalt fibers and matrix materials. Surface modification of basalt fibers and the dispersion property have become key points of research in recent years. This study focuses on the impact of a dispersant on surface modification. Basalt fibers were dispersed by polyethylene glycol (PEG) before modification with 3-aminopropyltriethoxysilane (KH550), which significantly increased the surface roughness, thus increasing the surface area and facilitating mechanical bonding. The morphology, structure, and composition were characterized via scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy analysis (XPS), respectively. The distribution characteristics of fiber were evaluated by the response surface method. When the mass fraction of PEG was 0.5 wt.%, the modification time was 2.5 hours, and the modification temperature was 60°C, the fiber dispersion degree in KH550 solution reached 83%. The grafting degree test indicates that the weight of the grafting increased to 6.67 times that of the undispersed basalt fibers. This enhancement allowed for greater grafting of the KH550, thereby optimizing the effect of modified fibers.

Impacts of polyethylene glycol (PEG) dispersity on protein adsorption, pharmacokinetics, and biodistribution of PEGylated gold nanoparticles.

PEGylated gold nanoparticles (PEG-AuNPs) are widely used in drug delivery, imaging and diagnostics, therapeutics, and biosensing. However, the effect of PEG dispersity on the molecular weight (M W) distribution of PEG grafted onto AuNP surfaces has been rarely reported. This study investigates the effect of PEG dispersity on the M W distribution of PEG grafted onto AuNP surfaces and its subsequent impact on protein adsorption and pharmacokinetics, by modifying AuNPs with monodisperse PEG methyl ether thiols (mPEG n -HS, n = 36, 45) and traditional polydisperse mPEG2k-SH (M W = 1900). Polydisperse PEG-AuNPs favor the enrichment of lower M W PEG fractions on their surface due to the steric hindrance effect, which leads to increased protein adsorption. In contrast, monodisperse PEG-AuNPs have a uniform length of PEG outlayer, exhibiting markedly lower yet constant protein adsorption. Pharmacokinetics analysis in tumor-bearing mice demonstrated that monodisperse PEG-AuNPs possess a significantly prolonged blood circulation half-life and enhanced tumor accumulation compared with their polydisperse counterpart. These findings underscore the critical, yet often underestimated, impacts of PEG dispersity on the in vitro and in vivo behavior of PEG-AuNPs, highlighting the role of monodisperse PEG in enhancing therapeutic nanoparticle performance.

Impact of polyethylene glycol molar mass and structural isomer of alcohol on the solubility and dissolution enhancement of mesalazine

This work reports the solubility of mesalazine (5-ASA) in mole fraction terms (x1,T) in mono-solvents of polyethylene glycol (PEG) 400, 1-propanol and 2-propanol along with their binary mixtures in different mass fractions of PEG 400 at 293.15–313.15 K and atmospheric pressure which measured experimentally by a shake-flask technique. The solubility of 5-ASA in these mixtures not only enhances with enhancing temperature, but also raises with raising PEG's mass fraction. Effect of PEG molar mass on the solubility of 5-ASA was also estimated by measuring its solubility in PEG 200 or 600 + 1- or 2-propanol mixtures at 298.15 K. Upon the same temperature and mass fraction of PEGs, the upward trend of 5-ASA mole fractions was: PEG 600 + 1-propanol > PEG 600 + 2-propanol > PEG 400 + 1-propanol > PEG 400 + 2-propanol > PEG 200 + 1-propanol > PEG 200 + 2-propanol indicating, the binary mixtures containing a high molar mass of PEG and 1-propanol with a hydroxyl group attached to carbon number 1 had a more solubilization power. Then, the experimental mole fractions were modelled by some cosolvency and activity coefficient models, and the model parameters were regressed. The back-computed mole fractions of 5-ASA by cosolvency models presented a better agreement with the experimental data than that of activity models and Jouyban-Acree model had the best performance (low overall average percentage deviation of 6.1 %). By means of enthalpy-entropy compensation analysis, non-linear ΔsolH° against ΔsolG° compensation plots with positive and negative slopes were achieved as a consequent of increasing 5-ASA solvation by PEG molecules and the solvent-structure loosing, respectively.

Extraction, structural characterization, and antioxidant activity of polysaccharides derived from Arctium lappa L.

Arctium lappa L. root has high nutritional and medicinal values and has been identified as a healthy food raw material by the Ministry of Health of the People's Republic of China. In the present study, an aqueous two-phase system (ATPS) of polyethylene glycol (PEG)-(NH4)2SO4 was used to extract Arctium lappa L. polysaccharides (ALPs) from the Arctium lappa L. roots, the optimal extraction conditions of crude ALPs were optimized by using the single-factor experiment and response surface methodology. The structure and composition of ALPs were determined by fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and high-performance liquid chromatography (HPLC). At the same time, the antioxidant activity of ALPs was investigated by in vitro antioxidant experiment. The optimized extraction parameters for extraction ALPs were as follows: the PEG relative molecular weight of 6,000, a quality fraction of PEG 25%, a quality fraction of (NH4)2SO4 18%, and an extraction temperature of 80°C. Under these conditions, the extraction rate of ALPs could reach 28.83%. FTIR, SEM and HPLC results showed that ALPs were typical acidic heteropolysaccharides and had uneven particle size distribution, an irregular shape, and a rough surface. The ALPs were chiefly composed of glucose, rhamnose, arabinose, and galactose with a molar ratio of 70.19:10.95:11.16:6.90. In addition, the ALPs had intense antioxidant activity in vitro with IC50 values in the ·OH radical (1.732 mg/ml), DPPH radical (0.29 mg/ml), and superoxide anion (0.15 mg/ml) scavenging abilities. The results showed that ATPS was an efficient method to extract polysaccharides and could be used for the extraction of other polysaccharides. These results indicated that ALPs had great prospects as a functional food and could be exploited in multiple fields.

Bulk cross-linked hydroxyethyl cellulose-silica composite membrane for acid-stable nanofiltration

This work focused on the construction of an acid-resistant composite nanofiltration membrane with the selective layer of bulk cross-linked hydroxyethyl cellulose (HEC)-silica and a support of porous polypropylene. Membranes were fabricated through in-situ sol-gel reaction and slot-die coating method employing tetraethyl orthosilicate (TEOS) as the silica precursor and cross-linking agent of HEC. Membrane structure and performance were tuned by controlling the hydrolysis time of TEOS and differentiating TEOS and HEC contents, and systematically characterized in terms of physico-chemical property, permeation attribution and acid stability. It was found that membrane performance was strongly correlated with the relative contents of C–O–Si and Si–O–Si bonds of the formed HEC-silica selective layer. High content of C–O–Si bond formed via condensation reaction of HEC and TEOS endowed the selective layer with denser network structure and good rejection ability. Both insufficient and excessive hydrolysis led to a poor rejection ability of formed membrane. The optimized HEC-silica membrane possessed an average pore size of about 1.43 nm within the scope of nanofiltration membrane, a high pure water permeability coefficient of around 10.5 LMH/bar, and a medium rejection of 85.2% to 500 mg/l Na2SO4 aqueous solution at 5.0 bar. No changes in both chemical structure and separation performance occurred with the HEC-silica composite membrane after being soaked in aqueous H2SO4 solution of 4.9 wt% for 7 days, while evident structure destruction and serious performance degradation occurred with the compared polyamide-based commercial membrane NF270. Long-term soaking test using 15.0 wt% H2SO4 aqueous solution for 30 days also demonstrated that the acid resistance HEC silica membrane was comparable with those reported acid stable nanofiltration membranes. Furthermore, the HEC-silica membrane also maintained its water permeation and solute rejection abilities during a 30-day continuous filtration of aqueous solution of 4.9 wt% H2SO4 and 50 mg/l polyethylene glycol fraction (PEG2000). The good acid resistance of the HEC-silica composite membrane was attributed to its bulk cross-linked network structure composed of C–O–Si, Si–O–Si and C–C bonds.

Preparation of thyme oil loaded κ-carrageenan-polyethylene glycol hydrogel membranes as wound care system

The present study is aimed at fabricating thyme oil loaded hydrogel membranes composed of κ-carrageenan (CG) and polyethylene glycol (PEG), which can provide moist environment and prevent infections for rapid wound healing. Membranes were prepared with different amounts of PEG via solvent casting technique under ambient conditions. Physicochemical properties of CG-PEG membranes as a function of the PEG content were investigated. The surface morphology of membranes displayed smoother surfaces with increasing PEG content up to 40%. In addition, the interaction of PEG with CG polymer chains was evaluated in terms of Free and bound PEG fraction within the membrane matrix. Furthermore, thyme oil (TO) was added to enhance the antibacterial properties of CG-PEG membranes. These membranes showed >95% antimicrobial activity against both gram-positive and gram-negative bacteria depending on the TO content. Suggesting the great potential of these membranes as a strong candidate for providing an effective antimicrobial nature in human healthcare.

The effect molecular weight of polyol components on shape memory effect of epoxy‐polyurethane composites

AbstractThis paper describes the experimental findings of the study of a series of PU/epoxy composites, which formed interpenetrating networks and have shape‐memory properties. The morphological variation for different chemical compositions and the influences of morphology on mechanical performance and shape‐memory behavior are discussed. Length and mass fraction of polyethylene glycol (PEG) units are chosen as the key parameters in this study. The molecular weight of PEG was varied from 400 (as such PEG units are unable to crystallize) to 1500, 4000, and 6000, which are crystallizable. It was shown that the crystallization of PEG units is the key parameter, which determines the mechanical performance and shape‐memory behavior of PU/epoxy composites in this study. DMTA results show the linear dependence of glass transition temperature and tensile strength, elongation, and other mechanical parameters on the amount of PEG in PU/epoxy composites independently of the amount of PEG unit lengths. The maximal value of shape fixation rate was achieved for 30–40 mass percentage of PEG 4000 (4.5 × 10−2 s−1 at Tg + 20°C) or PEG 6000(4.1 × 10−2 s−1 at Tg + 20°C) in PU/epoxy composites.

Double‐network polyvinyl alcohol composite hydrogel with self‐healing and low friction

AbstractPolyvinyl alcohol (PVA) hydrogel is considered the most promising candidate for artificial cartilage because of its good lubricity and low permeability. However, the efficacy of single‐network PVA hydrogels under variable loads has not yet been determined. In this study, a one‐step physical‐cross‐linking method was used to compose PVA/PEG double‐network composite hydrogels. We changed the polyethylene glycol (PEG) content of the composite gel and tested the frictional‐wear performance under different loads and speeds. With the mass fraction of PEG at 30 wt.%, the hardness of the PVA/PEG composite gel increased to 167.7% that of pure PVA. Under dry‐friction conditions, the average coefficient of friction was approximately 0.14 and the wear rate on the surface of the hydrogel was insignificant. The cross‐linking between PVA and PEG greatly enhanced the stability of the composite hydrogel polymer network. The structure of the composite gel was analyzed by a variety of standard methods. The hydrogel has excellent biocompatibility and self‐healing ability and is a self‐lubricating, self‐healing candidate material for articular‐cartilage repair.

Brij-stabilized zein nanoparticles as potential drug carriers

The current study was designed to provide a preliminary physico-chemical characterization of zein nanosystems prepared with various Brij surfactants (for the first time to the best of our knowledge) as a function of various external stimuli such as temperature, pH, serum incubation and the freeze-drying process. The results demonstrate that when Brijs are characterized by unsaturation (C18), considerable stabilization of the colloidal structure is promoted while the length of the polyethylene glycol fraction does not significantly modulate the physico-chemical properties of the nanosystems. Specifically, dynamic light scattering and nanoparticle tracking analysis demonstrated that the use of 0.2 % w/v of Brij O10 promoted the formation of stable zein nanosystems with mean sizes of ∼150 nm and a narrow size distribution, preserving their structures at various pHs and temperatures. The use of mannitol as cryoprotectant resulted in a formulation that can easily be re-suspended in water after the freeze-drying process. This nanoformulation demonstrated that it efficiently retained different amounts of both hydrophilic and lipophilic compounds and showed a prolonged release of the entrapped molecules. In addition, the nanosystems showed a favorable degree of in vitro safety on various cell lines when a concentration <50 μg/mL of protein was used, demonstrating the potential application of Brij O10-stabilized zein nanoparticles as innovative nanocarriers of several active compounds.

Efficient utilization of interparticle mesopores in aluminosilicate towards thermal energy storage

Porous confinement, a method to prepare form-stable composite phase change materials (PCMs) by impregnating PCMs into the pores of porous scaffold materials, is proven to be an extraordinarily effective mean to address the leakage problem of PCMs during the phase transition process. For the energy storage capacities of composite PCMs are closely associated with the pore structure of scaffold materials, the research on the correlation between the structure of mesoporous scaffold materials and its loaded capability phase change materials is conducive to enriching the research system of heat storage materials. Herein, a novel form-stable composite PCM was fabricated successfully by integrating polyethylene glycol (PEG) into the mesopores of nano-aluminosilicate aggregates (n-ASA). The structure and the thermal properties of the samples were characterized. The results indicated that n-ASA had a self-sustaining microstructure by the aggregation of individual granules, and a very high mesopore content of 98.3 % and mesopore volume of 1.16 cm3/g. The maximum mass fraction of PEG loaded in the composite can reach up to 77.5 % and the melting latent heat of n-ASA/PEG were 133.8 J/g and 115.0 J/g, respectively. An increasement of 42.4 % in thermal conductivity of PEG was achieved after loading it into n-ASA with interconnected pores due to the provision of a faster heat transfer channel. Moreover, the thermal characteristics of n-ASA/PEG had no distinct change after 200 thermal cycles, indicating its prominent thermal reliability and stability. It is convinced that the mesopores of n-ASA are actually preferable over the micro- and macro-pores for holding PEG, and the synthesized n-ASA/PEG composite would be a prospective and potential candidate for low-temperature heat storage applications.

The protein extraction method of Metroxylon sagu leaf for high-resolution two-dimensional gel electrophoresis and comparative proteomics

BackgroundSago palm (Metroxylon sagu) is a versatile crop and has been hailed as the next viable commodity in Sarawak, Malaysia. Sago palm can thrive in the harsh swampy peat, from low flooded areas to uplands and in acidic to neutral soils. Sago palm has been neglected and unfortunately, very little is known about the sago palm proteome. This study aimed to determine the best protein extraction method of Metroxylon sagu for the two-dimensional gel electrophoresis (2-DE) and its comparative analysis.ResultsTo perform good proteome research, the most critical step is to establish a method that gives the best quality of extracted total proteins. Five different protein extraction protocols: polyethylene glycol (PEG) fractionation method, phenol extraction method, TCA–acetone method, the combination of phenol and TCA–acetone extraction method and imidazole method were compared to develop an optimized protein extraction method for two-dimensional gel electrophoresis analysis of Metroxylon sagu. The PEG fractionation method was found to give the most reproducible gels with the highest number of spots and highest protein concentration followed by phenol extraction method. The lowest number of spots was observed in the imidazole method. The PEG fractionation method provides improved resolution and reproducibility of 2-DE and reduces the time required to analyze samples. Partitioning Rubisco by polyethylene glycol (PEG) fractionation provides clearer detection of low abundance protein. Hence, the results from this study propose PEG fractionation as the effective protein extraction method for 2-DE proteomic studies of Metroxylon sagu.ConclusionIn this study, the PEG fractionation method is considered as the best extraction method for 2-DE proteomic studies of Metroxylon sagu in terms of yield, gel quality, spot numbers, and quantities of proteins.

Determining Conformations and Sizes of Polyethylene Glycol Macromolecules in Water–Polyethylene Glycol–LiOH Systems by the Viscometry Method

The kinematical viscosity of water-polyethylene glycol-LiOH systems is studied at 293.15 K for the LiOH molar fraction of 0–0.05 and the PEG concentration of 0–5 g/length. Polyethylene glycol fractions of different molecular masses (1000, 1500, 3000, 4000, and 6000) are considered. Experimental data on the kinematic viscosity for a given LiOH concentration are used to calculate the following quantities: intrinsic viscosity of studied solutions, Huggins coefficient, parameter α in the Mark-Houwink equation, swelling coefficient of polyethylene glycol macromolecules, intrinsic viscosity in the θ solvent, mean square distance of the PEG macromolecular chain in the solution and in the θ solvent, length of the Kuhn segment in the solution and the θ solvent. It is shown that macromolecular polyethylene glycol coils are permeable for the surrounding liquid (water-LiOH) and that their volumes decrease and the macromolecule flexibility increases with increasing LiOH concentration.

Effect of PEG loading on the rheological stability of bitumen/PE/PEG blends based on network structure evolution

Polyethylene (PE) and polyethylene glycol (PEG) are employed to modify bitumen. The rheological stability of PE/PEG modified bitumen is studied by analyzing complex modulus (G*) variation with temperature. It is found that the starting temperature of G* plateau monotonously decreases as PEG fraction increases, showing a reduction of high temperature susceptibility. In addition, a gradual transition from viscous to elastic behavior happens in the modified bitumen as the PEG loading increases. DSC and XRD results found that PEG incorporation causes a minor influence on the crystalline behavior of PE. Phase separation evolution suggests that the dispersed PEG-rich droplets can effectively stabilize the PE-rich network structure induced by viscoelastic phase separation. This is the probable reason for then improvement of rheological stability and elasticity of bitumen/PE/PEG blends with high fraction of PEG.

Effect of etoposide on grass pea DNA topoisomerase II: an in silico, in vivo, and in vitro assessments

BackgroundEtoposide is one of the most potential anti-cancerous drugs that targets topoisomerase II (topoII) and inhibits its activity by ligation with the DNA molecule.ResultsIn silico study confirmed that the etoposide-binding sites of topoII are conserved among the plants and human. The efficacy of the drug on plant system was initially assessed using germinated grass pea (Lathyrus sativus L.) seedlings (in vivo) in relation to radicle length and mitotic index. The callus system (in vitro) was also used to elucidate the effect of etoposide on callus growth kinetics. Furthermore, it was observed that etoposide able to inhibit the division of polyploid cells induced by colchicine treatment (0.5%, 8 h). To determine the molecular interaction, topoII was isolated from young grass pea leaves using polyethylene glycol fractionation and ammonium sulphate precipitation followed by column chromatography on CM-Sephadex (C-25). The plasmid linearization assays by isolated plant topoII in the presence of etoposide significantly revealed the functional similarity of plants and human topoII. Results indicated that the effect of etoposide on plant topoII is significant.ConclusionsThis study may pave the way to develop a plant-based assay system for screening the topoisomerase targeted anti-cancerous drugs, as it is convenient and cost-effective.

Use of molecular crowding for the detection of protein self-association by size-exclusion chromatography

The feasibility of employing molecular crowding cosolutes to facilitate the detection of protein self-association by zonal size exclusion chromatography is investigated. Theoretical considerations have established that although the cosolute-induced displacement of a self-association equilibrium towards the oligomeric state invariably occurs in the mobile phase of the column, that displacement is only manifested as a decreased protein elution volume for cosolutes sufficiently small to partition between the mobile and stationary phases. Indeed, the use of a crowding agent sufficiently large to be confined to the mobile phase gives rise to an increased elution volume that could be misconstrued as evidence of cosolute-induced protein dissociation. Those theoretical considerations are reinforced by experimental studies of α-chymotrypsin (a reversibly dimerizing enzyme) on Superdex 200. The use of cosolutes such as sucrose and small polyethylene glycol fractions such as PEG-2000 is therefore recommended for the detection of protein self-association by molecular crowding effects in size exclusion chromatography.

The effect of thermal activation for natural zeolite on the performance of ceramic membrane as Pb2+ ion adsorption

Zeolites known as molecular filters have the potential to adsorb heavy metals in wastewater, but zeolites in nature have many impurities, so it was activated to remove impurities and increase the effectiveness of zeolite adsorption. This work was conducted to determine the performance of thermally activated ceramic membrane as a heavy metal filter for wastewater. The ceramics made with the wet-mixing method are activated zeolite powder mixed with polyethylene glycol (PEG) solution which is useful as an adhesive as well as a pore-making agent. The fabrication was done of each with a PEG fraction (w/w) of 8.33%; 10.93%; 13.23%; 15.27%; 17.1%; and 18.75%, respectively. The flow test was performed using Pb solution as wastewater with concentration 200 ppm, and it was obtained ceramic permeability between of 1×10−11 thus 6×10−11m2, while UV-Vis spectroscopy was done to obtain the filter performance (C/C0), that is 0.13; 0.20; 0.32; 0.36; 0.45; 0.54. In conclusion zeolite membrane thermally activated can be used as heavy metals filter.

PEG Quantitation Using Reversed-Phase High-Performance Liquid Chromatography and Charged Aerosol Detection.

This chapter describes a method for the quantitation of polyethylene glycol (PEG) in PEGylated colloidal gold nanoparticles using a reversed-phase high-performance liquid chromatography (RP-HPLC) with charged aerosol detection. The method can be used to calculate the total PEG on the nanoparticle, as well as the bound and free unbound PEG fractions after a simple centrifugation step. This is a significant distinction as the bound PEG fraction affects biocompatibility, circulation time, and overall nanoparticle efficacy. PEG quantitation can be achieved through two methods, one involving the dissolution of colloidal gold nanoparticles by potassium cyanide (KCN) and the other by displacement of PEG by dithiothreitol (DTT). The methods outlined herein were applied to 30nm colloidal gold grafted with 20kDa PEG, but they can be easily adapted to any size colloidal gold nanoparticle and PEG chain length.

Leaf proteomics of drought-sensitive and -tolerant genotypes of fennel

Fennel is attracted attention as a useful resource as researching medicinal plant for drought tolerance. To elucidate the response mechanism in drought-sensitive and -tolerant genotypes of fennel leaf, a gel-free/label-free proteomic technique was used. Fifty-day-old plants were subjected to drought stress for 60days. The relative water and proline contents were decreased and increased in sensitive genotypes, respectively; however, they were not a big change in tolerant genotypes. Photosynthesis was decreased in the sensitive genotypes under drought; however, it was increased in the tolerant genotype. In both drought-sensitive and -tolerant genotypes, proteins related to protein metabolism and cell organization were predominately affected under drought stress. The abundance of phosphoribulokinase and phosphoglycerate kinase enzymes were decreased and increased in drought-sensitive and -tolerant genotypes, respectively; however, the abundance of RuBisCO and glyceraldehyde-3-phosphate dehydrogenase enzymes were increased and decreased in drought-sensitive and -tolerant genotypes, respectively. Under drought stress, the abundance of glycolysis-related proteins was decreased in sensitive genotypes; however, they were increased in tolerance genotypes. Commonly changed proteins with polyethylene glycol fractionation such as cobalamin-independent methionine synthase were decreased and increased in drought-sensitive and -tolerant genotypes, respectively. These results suggest that cobalamin-independent methionine synthetase is involved in the tolerance of drought-tolerant fennel leaf under drought stress.

Proteomic analysis of soybean seedling leaf under waterlogging stress in a time-dependent manner

Leaf is sensitive to environmental changes and exhibits specific responses to abiotic stress. To identify the response mechanism in soybean leaf under waterlogging stress, a gel-free/label-free proteomic technique combined with polyethylene glycol fractionation was used. Attenuated photosynthesis by waterlogging stress in the leaf of soybean seedlings was indicated from proteomic results. Defensive mechanisms such as reactive oxygen species (ROS) scavenging was also recognized. Cluster analysis revealed that proteins that exhibit characteristic dynamics in response to waterlogging were mainly related to photosynthesis. Among the identified photorespiration-related proteins, the protein abundance and enzyme activity of hydroxypyruvate reductase were transiently increased in control plants, but were clearly decreased in response to waterlogging stress. These results suggest that waterlogging directly impairs photosynthesis and photorespiration. Furthermore, hydroxypyruvate reductase may be a critical enzyme controlling the rate of photorespiration.