Based on the different hydrophobicities of the intermediates of proteins the various conformational intermediates of the refolding of a-amylase originally denatured with 8.0 mol/L urea solution were separated with hi...Based on the different hydrophobicities of the intermediates of proteins the various conformational intermediates of the refolding of a-amylase originally denatured with 8.0 mol/L urea solution were separated with high performance hydrophobic interaction chromatography(HPHIC). Compared to the separation of the same intermediates with weak anion exchange chromatography and size-exclusion chromatography the result obtained with HPHIC is the best It would be expected that HPHIC may be a strongly potential tool to separate intermediates of some proteins which cannot be, or cannot completely be refolded by HPHIC.展开更多
The thermal behaviors of five proteins in hydrophobic interaction chromatography （HIC） were investigated in the temperature range from 0 to 50℃. The thermodynamic parameters （△H°,△S°, △Cp°and △G...The thermal behaviors of five proteins in hydrophobic interaction chromatography （HIC） were investigated in the temperature range from 0 to 50℃. The thermodynamic parameters （△H°,△S°, △Cp°and △G°） of these proteins in the process of retention and unfolding were determined. The existence of enthalpy and entropy convergence with temperature was confirmed. The differences of the isoentropic and isoenthalpic temperatures for protein unfolding in HIC system from the traditional solution were elucidated.展开更多
The contributions of tetrahydrofurfuryl alcohol (THFA) and polyethylene glycol (PEG) to the renatured efficiency of a-chymotrypsin were investigated and compared with each other. The maximum increments of bioactivity...The contributions of tetrahydrofurfuryl alcohol (THFA) and polyethylene glycol (PEG) to the renatured efficiency of a-chymotrypsin were investigated and compared with each other. The maximum increments of bioactivity recovery of a-Chy were found to be 25.1% for THFA, 10.4% for PEG, respectively. The experimental results indicated that the denaturant solution containing THFA contributed more to the renaturation of a-Chy in high performance hydrophobic interaction chromatography (HPHIC) than that containing PEG, when the concentration of THFA was 3.2%, the bioactivity recovery of a-Chy is the highest.展开更多
neural network model based on backbone propagation was applied to Learn-ing and predicting the interaction between antiparallelly interactive peptide seg-ments in proteins.Hydrophobic properties pf residues were found...neural network model based on backbone propagation was applied to Learn-ing and predicting the interaction between antiparallelly interactive peptide seg-ments in proteins.Hydrophobic properties pf residues were found dominant in in-terpeptides.Weights of each kind of residues, obtained by this work,suggestedsome different scales for the hydrophobicity of the residue.These will be helpful in understanding polypeptide structure and protein folding.展开更多
The aggregation behavior of the mixture of cetyltrimethylammonium chloride(CTAC), a cationic surfactant, and moxifloxacin hydrochloride(MFH), a fourth-generation fluoroquinolone antibiotic drug, has been studied using...The aggregation behavior of the mixture of cetyltrimethylammonium chloride(CTAC), a cationic surfactant, and moxifloxacin hydrochloride(MFH), a fourth-generation fluoroquinolone antibiotic drug, has been studied using the conductivity technique in aqueous and alcoholic(EtOH, 1-PrOH, and 2-BuOH)media. The study was performed at several temperatures between 298.15 and 323.15 K at 5 K intervals.The assembly has been characterized by evaluating the micellar parameters, such as the critical micelle concentration(CMC) and the counter ion binding(β), of the CTAC + MFH mixture. The values of the CMC for the assembly of the CTAC + MFH mixture were reliant on the composition of alcohols in the mixed solvents and the temperature. The CMC values of the CTAC + MFH mixture increased with increasing temperature;that is, assembly was delayed by increased temperature. The micellization of the CTAC + MFH mixed system was delayed in alcoholic media. The observed-ΔG0mvalues for the association of the CTAC + MFH mixed system demonstrated a spontaneous aggregation process under all study conditions.Based on the-ΔH^(0)_(m) and +ΔS^(0)_(m) values, the association of the CTAC + MFH mixture is exothermic and the interaction forces acting between the CTAC and MFH species are hydrophobic, ion–dipole, and electrostatic interactions. The transfer properties and enthalpy–entropy compensation were also assessed and described comprehensively.展开更多
The rheology of the cationic guar （CG） solution was measured and the effects of potassium oleate （KOA） upon the rheological properties of CG solution were studied. The steady shear viscosity measurement has shown ...The rheology of the cationic guar （CG） solution was measured and the effects of potassium oleate （KOA） upon the rheological properties of CG solution were studied. The steady shear viscosity measurement has shown that the viscosity of CG solution increased dramatically in the presence of KOA. The viscosity enhancement of KOA upon CG solution can be approximate three orders in magnitude. The gel-like formation of CG solution is observed at the high concentration of KOA. The excess addition of KOA results in the phase separation of CG solution. The oscillatory rheological measurement has shown that the crossover modulus Gc （corresponding to either storage modulus G＇ or loss modulus G＇＇ at the frequency wc where G＇ equals G＇＇） for CG solution, decreases with the increasing the concentration of KOA in solution. On the other hand, the apparent relaxation time 7-app （=1/wc） increases with increasing the concentration of KOA in solution. Our experimental results suggest that for surfaetant such as KOA which has a stronger tendency to form micelles in solution, the cooperative hydrophobic interaction of polymer bound to surfactants is less necessary to the formation of aggregates in solution, especially at the high concentration of surfactants. In fact, with the increase of the concentration of KOA, the number of the aggregates which associate polymer together decreases whereas the intensity of these aggregates increases. The effect of temperature upon the aggregation is also significant. With the increase of temperature, the number of the aggregates increases whereas the intensity of these aggregates decreases, probably because the ionization of KOA increases at high temperature.展开更多
The effect of ethanol （C2H5OH）, propanol （C3H7OH）, and butanol （C4H9OH） upon the viscosity of tetradecyltrimethylammonium bromide （TTAB） solution in the presence or absence of KBr at 30℃was investigated, wher...The effect of ethanol （C2H5OH）, propanol （C3H7OH）, and butanol （C4H9OH） upon the viscosity of tetradecyltrimethylammonium bromide （TTAB） solution in the presence or absence of KBr at 30℃was investigated, where the surfactant concentration CS is kept constant. In the absence of KBr, the relative viscosity ηr of TTAB solution increases linearly with the alcohol concentration CA, indicating that the alcohols do not promote micelle formation of TTAB. In the presence of KBr, ηr linearly decreases with CA for C2H5OH, but it exhibits a maximum with increasing CA for C3H7OH or C4H9OH. The facts reveal that C2H5OH or C4H9OH promotes the micelle formation of TTAB. A possible explanation is that the hydrophobicity of the mieellar interior is enhanced by KBr, so that C2H5OH or C4H9OH can dissolve in micelle and promotes micelle formation. In the presence of KCl, which is less efficient in promoting the micelle formation of cationic surfactant, both C3H7OH and C4H9OH have only a slight effect on the micelle formation. In contrast, due to the hydrophilicity, C2H5OH cannot dissolve in micelles in the presence of KBr or KCl.展开更多
The renaturation and purification of recombinant human proinsulin (rh-proinsulin) expressed in E. coli with the unit of simultaneous renaturation and purification of protein (USRPP) in semi-preparative scale was studi...The renaturation and purification of recombinant human proinsulin (rh-proinsulin) expressed in E. coli with the unit of simultaneous renaturation and purification of protein (USRPP) in semi-preparative scale was studied. The result shows that rh-proinsulin extracted with 8.0 mol/L urea can be renatured and purified simultaneously in 45 minutes with the USRPP (1050 mm ID). The purity of rh-proinsulin was found to be more than 90% and the mass recovery to be more than 80%. The renaturation effect of rh-proinsulin with the USRPP was tested by enzyme cleavage for obtaining insulin. In addition, the result was further confirmed with RPLC, SDS-PAGE electrophoresis, and MALDI-TOF, respectively.展开更多
The addition of packing material for high performance hydrophobic interaction chromatograghy （HPHIC） into the denaturant solution to prevent, or depress protein aggregation in the denatuaration process is presented....The addition of packing material for high performance hydrophobic interaction chromatograghy （HPHIC） into the denaturant solution to prevent, or depress protein aggregation in the denatuaration process is presented. The renaturation of α-chymotrypsin （α-Chy） denatured with guanidine hydrochloride （GuHCl） solution indicated that renaturation efficiency can be enhanced from 36.1% to 59.0% by this new method. The structure of the ligand linking of HPHIC packings is also important for the protein renaturation.展开更多
We investigate the influence of an external electric field on the dewetting behavior of nitrogen-water systems between two hydrophobic plates using molecular dynamics simulations. It is found that the critical distanc...We investigate the influence of an external electric field on the dewetting behavior of nitrogen-water systems between two hydrophobic plates using molecular dynamics simulations. It is found that the critical distance of dewetting increases obviously with the electric field strength, indicating that the effective range of hydrophobic attraction is extended. The mechanism behind this interesting phenomenon is related to the rearrangement of hydrogen bond networks between water molecules induced by the external electric field. Changes in the hydrogen bond networks and in the dipole orientation of the water molecules result in the redistribution of the neutral nitrogen molecules, especially in the region close to the hydrophobic plates. Our findings may be helpful for understanding the effects of the electric field on the long-range hydrophobic interactions.展开更多
A novel hydrophobic medium with propyl as functional group and Sepharose 6B as matrix was designed and synthesized. The comparison of the hydrophobic medium synthesized with the commercial products was made by hydroph...A novel hydrophobic medium with propyl as functional group and Sepharose 6B as matrix was designed and synthesized. The comparison of the hydrophobic medium synthesized with the commercial products was made by hydrophobic interaction chromatography(HIC) in isolating recombinant hepatitis B surface antigen(r HBsAg). r HBsAg was further purified to the final products by following a downstream procedure . The results indicate that the synthesized hydrophobic medium possesses a stable structure and desired physical and chemical properties. They were used to purify r HBsAg with a high yield and purity. Both the immunity and stability of hepatitis vaccine made by the r HBsAg products have reached the same level as other similar kinds of products.展开更多
Background:Retinol dehydrogenase 8(RDH8)is a 312-amino acid(aa)protein involved in the visual cycle.Bound to the outer segment disk membranes of photoreceptors,it reduces all-trans-retinal to all-trans-retinol1 as one...Background:Retinol dehydrogenase 8(RDH8)is a 312-amino acid(aa)protein involved in the visual cycle.Bound to the outer segment disk membranes of photoreceptors,it reduces all-trans-retinal to all-trans-retinol1 as one of the rate-limiting steps of the visual cycle2.RDH8 is a member of the short-chain dehydrogenase/reductase family.Its C-terminal segment allows its membrane-anchoring through the postulated presence of an amphipathicα-helix and of 1 to 3 acyl groups at positions 299,302 and 3043.The secondary structure and membrane binding characteristics of RDH8 and its C-terminal segment have not yet been described.Methods:To evaluate the membrane binding of RDH8,the full-length protein(aa 1-312),a truncated form(aa 1-296),its C-terminal segment(aa 281-312 and 297-312)as well as different additional variants of this segment were used.The truncated protein binds membranes less efficiently than the full-length form.Thus,the C-terminal segment of RDH8 is essential for the binding and has thus been further examined.The intrinsic fluorescence of tryptophan residues at positions 289 and 310 of the wild-type C-terminal segment of RDH8 and the mutants W289F,W310F and W310R have thus been used to determine their extent of binding to lipid vesicles and to monitor their local environment.Unilamellar lipid vesicles composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine(POPC)or a mixture of POPC and 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine(POPS)were used to mimic the phospholipid content of the outer segment disk membranes of photoreceptors.Results:An increase in fluorescence intensity and in fluorescence lifetime is observed upon increasing the concentration of lipid vesicles.These data allowed calculating values of partition coefficient of the C-terminal segment of RDH8 varying between Kp=1.1 E6 to 1.7 E6.It is noteworthy that the observation of a more intense shift to lower wavelengths upon membrane binding of the mutant W310R and W310F indicates a deeper incorporation of the remaining tryptophan residue at position 289 into the lipid bilayer.The secondary structure of the C-terminal segment of RDH8 observed by circular dichroism and infrared spectroscopy shows a superposition ofα-helical,β-turn and unordered structures.Conclusions:The peptides derived from the C-terminal segment of RDH8 show a strong binding to lipid vesicles.These strength of binding is independent of the type of lipid and the presence of a mutation.展开更多
Polymerization-induced self-assembly(PISA)enables the simultaneous growth and self-assembly of block copolymers in one pot and therefore has developed into a high-efficiency platform for the preparation of polymer ass...Polymerization-induced self-assembly(PISA)enables the simultaneous growth and self-assembly of block copolymers in one pot and therefore has developed into a high-efficiency platform for the preparation of polymer assemblies with high concentration and excellent reproducibility.During the past decade,the driving force of PISA has extended from hydrophobic interactions to other supramolecular interactions,which has greatly innovated the design of PISA,enlarged the monomer/solvent toolkit,and endowed the polymer assemblies with intrinsic dynamicity and responsiveness.To unravel the important role of driving forces in the formation of polymeric assemblies,this review summarized the recent development of PISA from the perspective of driving forces.Motivated by this goal,here we give a brief overview of the basic principles of PISA and systematically discuss the various driving forces in the PISA system,including hydrophobic interactions,hydrogen bonding,electrostatic interactions,andπ-πinteractions.Furthermore,PISA systems that are driven and regulated by crystallization or liquid crystalline ordering were also highlighted.展开更多
In this work,a new type of hydrophobic stationary phase that provide electrostatic interactions with analytes was developed by bondingβ-phenylethylamine as a functional ligand to silica.This stationary phase can sepa...In this work,a new type of hydrophobic stationary phase that provide electrostatic interactions with analytes was developed by bondingβ-phenylethylamine as a functional ligand to silica.This stationary phase can separate proteins with similar hydrophobicity that traditional hydrophobic resins cannot.Hen egg white was separated to examine the selectivity.The results show that the introduced electrostatic interactions are an important factor for the resolution enhancement and the new resin could have important applications in separation and purification of biological macromolecules.展开更多
The demand for in-situ detection of latent fingerprints(LFPs)in ways of high sensitivity,high selectivity,high contrast,low cost and user-friendly is still urgent.To overcome this challenge,a moisture-stable,red-emitt...The demand for in-situ detection of latent fingerprints(LFPs)in ways of high sensitivity,high selectivity,high contrast,low cost and user-friendly is still urgent.To overcome this challenge,a moisture-stable,red-emitting fluoride phosphor K_(3)AlF_(6):Mn^(4+)(KAF:Mn^(4+))with an organic hydrophobic skin was prepared.The phosphor has a uniform and superfine morphology with excellent luminescence properties.More importantly,this non-ultraviolet(UV)or non-near infrared(NIR)induced phosphor was proved to be an ideal fluorescent label for LFP imaging,which is both friendly for touch DNA analysis and compatible to forensic light sources.The well-defined ridge details with little background interference on various surfaces were presented by the oleic acid(OA)modified KAF:Mn^(4+)(KAF:Mn^(4+)-OA)phosphor in few seconds using the powder dusting method.To confirm the high selectivity of KAF:Mn^(4+)-OA for LFP imaging,an efficient quantitative evaluation method is proposed with the aid of ImageJ&Origin software.Due to the superiority of the Mn^(4+)-doped fluoride for the rapid imaging of LFPs in terms of lowcost,high compatibility and good availability,it is expected to be a promising candidate for forensic science as well as fluorescence imaging in other fields instead of rare earth luminescent materials.展开更多
The solubilities of benzene and diphenyl in mixed solvents of t-butyl alcohol(TBA) and water with different salts have been determined at T = 298.15, 303.15, 308.15 and 313.15K. The molar fraction of TBA [x(TBA)] in m...The solubilities of benzene and diphenyl in mixed solvents of t-butyl alcohol(TBA) and water with different salts have been determined at T = 298.15, 303.15, 308.15 and 313.15K. The molar fraction of TBA [x(TBA)] in mixed solvent is 0.045, and the molality of the salts (m_s)in mixed solvents are 0.000, 0.250, 0.500, 0.750 and 1.000 mol/kg, respectively. The standard Gibbsenergies of solution of benzene and diphenyl in the mixed solvents have also been calculated basedon the solubility data. The effects of different salts on the hydrophobic interaction (HI) forbenzene-benzene pair in the systems were discussed.展开更多
The hydrophobic amino acid residues of a denatured protein molecule tend to react with the particles of the stationary phase of hydrophobic interaction chromatography (STHIC). These hydrophobic interactions prevent th...The hydrophobic amino acid residues of a denatured protein molecule tend to react with the particles of the stationary phase of hydrophobic interaction chromatography (STHIC). These hydrophobic interactions prevent the denatured protein molecules from aggregating with each other. The STHIC can provide high enough energy to a denatured protein molecule to make it dehydration and to refold it into its native or various intermediate states. The outcome not only depends on the specific interactions between amino acids, the structure of STHIC, but also depends on the association between the STHIC and mobile phase. The mechanism of protein refolding and the principle of its quality control by HPHIC were also presented. By appropriate selection of the Chromatographie condition, several denatured proteins can be refolded and separated simultaneously in a single Chromatographic run. A specially designed unit, with diameter much larger than its length, was designed and employed for both laboratory and preparative scales. That unit for the simultaneous renaturation and purification of proteins (USRPP) had the following four functions: to completely remove denaturant, to renature proteins, to separate renatured proteins from impurities, and to easily recycle waste denaturant. The efficiencies of refolding and purification of proteins by the USRPP are almost comparable to a usual long Chromatographie column in laboratory. In preparative scale, USRPP can be easily, rapidly, and economically applied requiring a low pressure gradient. As an example, recombinant human interferon-γ is employed to elucidate the application of the preparative USRPP.展开更多
This paper reports an easy and effective way to fabricate polystyrene/poly(N-isopropylacrylamide)(PS/PNIPAM)core-shell particles and PNIPAM hollow spheres.The main point of the method is to take advantage of the hydro...This paper reports an easy and effective way to fabricate polystyrene/poly(N-isopropylacrylamide)(PS/PNIPAM)core-shell particles and PNIPAM hollow spheres.The main point of the method is to take advantage of the hydrophobic interaction between initiator and PS particles.The hydrophobic azodiisobutyronitriles automatically concentrate around the PS particles and initiate polymerization of N-isopropylacrylamide(NIPAM)and the crosslinkermethylene bisacrylamide(MBA),which dissolve in the aqueous phase,at the surface of the PS nanoparticles.Then,PNIPAM adheres to the PS particles to form a coreshell structure as a result of their hydrophobic interaction.This interaction is due to the unique property of PNIPAM,namely,its ability to transition from hydrophilic to hydrophobic when the temperature rises to 32℃.Furthermore,the hollow PNIPAM spheres were obtained by etching the PS core with chloroform.展开更多
Peptide self-assembles with bionic properties have been widely utilized for bioactive drugs and biomedical materials.Collagen mimetic peptide(CMP)gains more attention due to its unique advantages in biosecurity and fu...Peptide self-assembles with bionic properties have been widely utilized for bioactive drugs and biomedical materials.Collagen mimetic peptide(CMP)gains more attention due to its unique advantages in biosecurity and function.Unfortunately,the self-assembly mechanism of CMP,particularly the effect of intermolecular forces on its self-assembly behavior and morphology,is still unrecognized.Herein,the hydrophilic glycidol(GCD)and hydrophobic Y-glycidyl ether oxypropyl trimethoxysilane(GLH)were grafted onto the side chains of CMP through the ring-opening reaction(GCD/CMP,GLH/CMP).Subsequently,the effects of hydrophilic and hydrophobic interactions on the self-assembly behavior and morphology of CMP were further studied.The results substantiated that the GCD/CMP and GLH/CMP self-assembly followed“nucleation-growth”mechanism,and the supererogatory hydrophilic and hydrophobic groups prolonged the nucleation and growth time of CMP self-assembly.Noted that the hydrophilic interaction had stronger driving effects than hydrophobic interaction on the self-assembly of CMP.The GCD/CMP and GLH/CMP self-assembles exhibited fibrous 3D network and microsphere morphology,respectively.Furthermore,the GLH/CMP self-assembles had better resistance to degradation.Consequently,the microtopography and degradation properties of CMP self-assembles could be controlled by the hydrophilic and hydrophobic interactions between CMP,which would further provide a way for subsequent purposeful design of biomedical materials.展开更多
文摘Based on the different hydrophobicities of the intermediates of proteins the various conformational intermediates of the refolding of a-amylase originally denatured with 8.0 mol/L urea solution were separated with high performance hydrophobic interaction chromatography(HPHIC). Compared to the separation of the same intermediates with weak anion exchange chromatography and size-exclusion chromatography the result obtained with HPHIC is the best It would be expected that HPHIC may be a strongly potential tool to separate intermediates of some proteins which cannot be, or cannot completely be refolded by HPHIC.
文摘The thermal behaviors of five proteins in hydrophobic interaction chromatography （HIC） were investigated in the temperature range from 0 to 50℃. The thermodynamic parameters （△H°,△S°, △Cp°and △G°） of these proteins in the process of retention and unfolding were determined. The existence of enthalpy and entropy convergence with temperature was confirmed. The differences of the isoentropic and isoenthalpic temperatures for protein unfolding in HIC system from the traditional solution were elucidated.
基金These projects No. 39880003 and 20175016 were supported by the National Natural Science Foundation of China.
文摘The contributions of tetrahydrofurfuryl alcohol (THFA) and polyethylene glycol (PEG) to the renatured efficiency of a-chymotrypsin were investigated and compared with each other. The maximum increments of bioactivity recovery of a-Chy were found to be 25.1% for THFA, 10.4% for PEG, respectively. The experimental results indicated that the denaturant solution containing THFA contributed more to the renaturation of a-Chy in high performance hydrophobic interaction chromatography (HPHIC) than that containing PEG, when the concentration of THFA was 3.2%, the bioactivity recovery of a-Chy is the highest.
文摘neural network model based on backbone propagation was applied to Learn-ing and predicting the interaction between antiparallelly interactive peptide seg-ments in proteins.Hydrophobic properties pf residues were found dominant in in-terpeptides.Weights of each kind of residues, obtained by this work,suggestedsome different scales for the hydrophobicity of the residue.These will be helpful in understanding polypeptide structure and protein folding.
基金funded by Institutional Fund Projects (IFPIP:515-961-1443)technical and financial support provided by the Ministry of Education and King Abdulaziz University, DSR, Jeddah, Saudi Arabia。
文摘The aggregation behavior of the mixture of cetyltrimethylammonium chloride(CTAC), a cationic surfactant, and moxifloxacin hydrochloride(MFH), a fourth-generation fluoroquinolone antibiotic drug, has been studied using the conductivity technique in aqueous and alcoholic(EtOH, 1-PrOH, and 2-BuOH)media. The study was performed at several temperatures between 298.15 and 323.15 K at 5 K intervals.The assembly has been characterized by evaluating the micellar parameters, such as the critical micelle concentration(CMC) and the counter ion binding(β), of the CTAC + MFH mixture. The values of the CMC for the assembly of the CTAC + MFH mixture were reliant on the composition of alcohols in the mixed solvents and the temperature. The CMC values of the CTAC + MFH mixture increased with increasing temperature;that is, assembly was delayed by increased temperature. The micellization of the CTAC + MFH mixed system was delayed in alcoholic media. The observed-ΔG0mvalues for the association of the CTAC + MFH mixed system demonstrated a spontaneous aggregation process under all study conditions.Based on the-ΔH^(0)_(m) and +ΔS^(0)_(m) values, the association of the CTAC + MFH mixture is exothermic and the interaction forces acting between the CTAC and MFH species are hydrophobic, ion–dipole, and electrostatic interactions. The transfer properties and enthalpy–entropy compensation were also assessed and described comprehensively.
文摘The rheology of the cationic guar （CG） solution was measured and the effects of potassium oleate （KOA） upon the rheological properties of CG solution were studied. The steady shear viscosity measurement has shown that the viscosity of CG solution increased dramatically in the presence of KOA. The viscosity enhancement of KOA upon CG solution can be approximate three orders in magnitude. The gel-like formation of CG solution is observed at the high concentration of KOA. The excess addition of KOA results in the phase separation of CG solution. The oscillatory rheological measurement has shown that the crossover modulus Gc （corresponding to either storage modulus G＇ or loss modulus G＇＇ at the frequency wc where G＇ equals G＇＇） for CG solution, decreases with the increasing the concentration of KOA in solution. On the other hand, the apparent relaxation time 7-app （=1/wc） increases with increasing the concentration of KOA in solution. Our experimental results suggest that for surfaetant such as KOA which has a stronger tendency to form micelles in solution, the cooperative hydrophobic interaction of polymer bound to surfactants is less necessary to the formation of aggregates in solution, especially at the high concentration of surfactants. In fact, with the increase of the concentration of KOA, the number of the aggregates which associate polymer together decreases whereas the intensity of these aggregates increases. The effect of temperature upon the aggregation is also significant. With the increase of temperature, the number of the aggregates increases whereas the intensity of these aggregates decreases, probably because the ionization of KOA increases at high temperature.
基金Supported by Research Foundation of Overseas Chinese Affairs Office,the State Council,P.R.China,and FujianProvincial Science and Technology Creation Foundation for Young Researchers(No.2 0 0 1J0 2 3)
文摘Sieve effect, complexation, ionic exchange, electrostatic interaction, hydrogen bonding, hydrophobic interaction, and molecular recognition based on molecular imprinting are comprehensively discussed.
文摘The effect of ethanol （C2H5OH）, propanol （C3H7OH）, and butanol （C4H9OH） upon the viscosity of tetradecyltrimethylammonium bromide （TTAB） solution in the presence or absence of KBr at 30℃was investigated, where the surfactant concentration CS is kept constant. In the absence of KBr, the relative viscosity ηr of TTAB solution increases linearly with the alcohol concentration CA, indicating that the alcohols do not promote micelle formation of TTAB. In the presence of KBr, ηr linearly decreases with CA for C2H5OH, but it exhibits a maximum with increasing CA for C3H7OH or C4H9OH. The facts reveal that C2H5OH or C4H9OH promotes the micelle formation of TTAB. A possible explanation is that the hydrophobicity of the mieellar interior is enhanced by KBr, so that C2H5OH or C4H9OH can dissolve in micelle and promotes micelle formation. In the presence of KCl, which is less efficient in promoting the micelle formation of cationic surfactant, both C3H7OH and C4H9OH have only a slight effect on the micelle formation. In contrast, due to the hydrophilicity, C2H5OH cannot dissolve in micelles in the presence of KBr or KCl.
文摘The renaturation and purification of recombinant human proinsulin (rh-proinsulin) expressed in E. coli with the unit of simultaneous renaturation and purification of protein (USRPP) in semi-preparative scale was studied. The result shows that rh-proinsulin extracted with 8.0 mol/L urea can be renatured and purified simultaneously in 45 minutes with the USRPP (1050 mm ID). The purity of rh-proinsulin was found to be more than 90% and the mass recovery to be more than 80%. The renaturation effect of rh-proinsulin with the USRPP was tested by enzyme cleavage for obtaining insulin. In addition, the result was further confirmed with RPLC, SDS-PAGE electrophoresis, and MALDI-TOF, respectively.
基金supported by the National Natural Science Foundation of China(No.39880003 and 20175016).
文摘The addition of packing material for high performance hydrophobic interaction chromatograghy （HPHIC） into the denaturant solution to prevent, or depress protein aggregation in the denatuaration process is presented. The renaturation of α-chymotrypsin （α-Chy） denatured with guanidine hydrochloride （GuHCl） solution indicated that renaturation efficiency can be enhanced from 36.1% to 59.0% by this new method. The structure of the ligand linking of HPHIC packings is also important for the protein renaturation.
基金Project supported by the National Natural Science Foundation of China (Grant No. 11875237)。
文摘We investigate the influence of an external electric field on the dewetting behavior of nitrogen-water systems between two hydrophobic plates using molecular dynamics simulations. It is found that the critical distance of dewetting increases obviously with the electric field strength, indicating that the effective range of hydrophobic attraction is extended. The mechanism behind this interesting phenomenon is related to the rearrangement of hydrogen bond networks between water molecules induced by the external electric field. Changes in the hydrogen bond networks and in the dipole orientation of the water molecules result in the redistribution of the neutral nitrogen molecules, especially in the region close to the hydrophobic plates. Our findings may be helpful for understanding the effects of the electric field on the long-range hydrophobic interactions.
文摘A novel hydrophobic medium with propyl as functional group and Sepharose 6B as matrix was designed and synthesized. The comparison of the hydrophobic medium synthesized with the commercial products was made by hydrophobic interaction chromatography(HIC) in isolating recombinant hepatitis B surface antigen(r HBsAg). r HBsAg was further purified to the final products by following a downstream procedure . The results indicate that the synthesized hydrophobic medium possesses a stable structure and desired physical and chemical properties. They were used to purify r HBsAg with a high yield and purity. Both the immunity and stability of hepatitis vaccine made by the r HBsAg products have reached the same level as other similar kinds of products.
文摘Background:Retinol dehydrogenase 8(RDH8)is a 312-amino acid(aa)protein involved in the visual cycle.Bound to the outer segment disk membranes of photoreceptors,it reduces all-trans-retinal to all-trans-retinol1 as one of the rate-limiting steps of the visual cycle2.RDH8 is a member of the short-chain dehydrogenase/reductase family.Its C-terminal segment allows its membrane-anchoring through the postulated presence of an amphipathicα-helix and of 1 to 3 acyl groups at positions 299,302 and 3043.The secondary structure and membrane binding characteristics of RDH8 and its C-terminal segment have not yet been described.Methods:To evaluate the membrane binding of RDH8,the full-length protein(aa 1-312),a truncated form(aa 1-296),its C-terminal segment(aa 281-312 and 297-312)as well as different additional variants of this segment were used.The truncated protein binds membranes less efficiently than the full-length form.Thus,the C-terminal segment of RDH8 is essential for the binding and has thus been further examined.The intrinsic fluorescence of tryptophan residues at positions 289 and 310 of the wild-type C-terminal segment of RDH8 and the mutants W289F,W310F and W310R have thus been used to determine their extent of binding to lipid vesicles and to monitor their local environment.Unilamellar lipid vesicles composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine(POPC)or a mixture of POPC and 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine(POPS)were used to mimic the phospholipid content of the outer segment disk membranes of photoreceptors.Results:An increase in fluorescence intensity and in fluorescence lifetime is observed upon increasing the concentration of lipid vesicles.These data allowed calculating values of partition coefficient of the C-terminal segment of RDH8 varying between Kp=1.1 E6 to 1.7 E6.It is noteworthy that the observation of a more intense shift to lower wavelengths upon membrane binding of the mutant W310R and W310F indicates a deeper incorporation of the remaining tryptophan residue at position 289 into the lipid bilayer.The secondary structure of the C-terminal segment of RDH8 observed by circular dichroism and infrared spectroscopy shows a superposition ofα-helical,β-turn and unordered structures.Conclusions:The peptides derived from the C-terminal segment of RDH8 show a strong binding to lipid vesicles.These strength of binding is independent of the type of lipid and the presence of a mutation.
基金National Natural Science Foundation of China,Grant/Award Number:21905171。
文摘Polymerization-induced self-assembly(PISA)enables the simultaneous growth and self-assembly of block copolymers in one pot and therefore has developed into a high-efficiency platform for the preparation of polymer assemblies with high concentration and excellent reproducibility.During the past decade,the driving force of PISA has extended from hydrophobic interactions to other supramolecular interactions,which has greatly innovated the design of PISA,enlarged the monomer/solvent toolkit,and endowed the polymer assemblies with intrinsic dynamicity and responsiveness.To unravel the important role of driving forces in the formation of polymeric assemblies,this review summarized the recent development of PISA from the perspective of driving forces.Motivated by this goal,here we give a brief overview of the basic principles of PISA and systematically discuss the various driving forces in the PISA system,including hydrophobic interactions,hydrogen bonding,electrostatic interactions,andπ-πinteractions.Furthermore,PISA systems that are driven and regulated by crystallization or liquid crystalline ordering were also highlighted.
基金supported by the National Natural Science Foundation in China(No.21006077)the Foundation of Northwest University(No.09NW14)
文摘In this work,a new type of hydrophobic stationary phase that provide electrostatic interactions with analytes was developed by bondingβ-phenylethylamine as a functional ligand to silica.This stationary phase can separate proteins with similar hydrophobicity that traditional hydrophobic resins cannot.Hen egg white was separated to examine the selectivity.The results show that the introduced electrostatic interactions are an important factor for the resolution enhancement and the new resin could have important applications in separation and purification of biological macromolecules.
基金financially supported by the National Natural Science Foundation of China(51962005)China Scholarship Council(201908505044)+6 种基金the cultivation project of the State Key Laboratory of Green Development and High-value Utilization of Ionic Rare Earth Resources in Jiangxi Province(20194AFD44003)Natural Science Foundation of Jiangxi Province(20192BAB206010)Scientific and Technological Project of Chongqing Education Commission(KJZD-M202000301,KJZD-K201800301)Science and Technology Program of Ganzhou city[2017]179the Youth Jinggang Scholars Program in Jiangxi Province[2018]82Key Program of Southwest University of Political Science and Law(2018XZZD-07,2019XZXS-207)Postgraduate Innovation Special Fund Project of Jiangxi Province(YC2019-S294).
文摘The demand for in-situ detection of latent fingerprints(LFPs)in ways of high sensitivity,high selectivity,high contrast,low cost and user-friendly is still urgent.To overcome this challenge,a moisture-stable,red-emitting fluoride phosphor K_(3)AlF_(6):Mn^(4+)(KAF:Mn^(4+))with an organic hydrophobic skin was prepared.The phosphor has a uniform and superfine morphology with excellent luminescence properties.More importantly,this non-ultraviolet(UV)or non-near infrared(NIR)induced phosphor was proved to be an ideal fluorescent label for LFP imaging,which is both friendly for touch DNA analysis and compatible to forensic light sources.The well-defined ridge details with little background interference on various surfaces were presented by the oleic acid(OA)modified KAF:Mn^(4+)(KAF:Mn^(4+)-OA)phosphor in few seconds using the powder dusting method.To confirm the high selectivity of KAF:Mn^(4+)-OA for LFP imaging,an efficient quantitative evaluation method is proposed with the aid of ImageJ&Origin software.Due to the superiority of the Mn^(4+)-doped fluoride for the rapid imaging of LFPs in terms of lowcost,high compatibility and good availability,it is expected to be a promising candidate for forensic science as well as fluorescence imaging in other fields instead of rare earth luminescent materials.
文摘The solubilities of benzene and diphenyl in mixed solvents of t-butyl alcohol(TBA) and water with different salts have been determined at T = 298.15, 303.15, 308.15 and 313.15K. The molar fraction of TBA [x(TBA)] in mixed solvent is 0.045, and the molality of the salts (m_s)in mixed solvents are 0.000, 0.250, 0.500, 0.750 and 1.000 mol/kg, respectively. The standard Gibbsenergies of solution of benzene and diphenyl in the mixed solvents have also been calculated basedon the solubility data. The effects of different salts on the hydrophobic interaction (HI) forbenzene-benzene pair in the systems were discussed.
基金This work was supposed by the National Natural ScienceFoundation of China (Grant Nos.39880003 and 20175016).
文摘The hydrophobic amino acid residues of a denatured protein molecule tend to react with the particles of the stationary phase of hydrophobic interaction chromatography (STHIC). These hydrophobic interactions prevent the denatured protein molecules from aggregating with each other. The STHIC can provide high enough energy to a denatured protein molecule to make it dehydration and to refold it into its native or various intermediate states. The outcome not only depends on the specific interactions between amino acids, the structure of STHIC, but also depends on the association between the STHIC and mobile phase. The mechanism of protein refolding and the principle of its quality control by HPHIC were also presented. By appropriate selection of the Chromatographie condition, several denatured proteins can be refolded and separated simultaneously in a single Chromatographic run. A specially designed unit, with diameter much larger than its length, was designed and employed for both laboratory and preparative scales. That unit for the simultaneous renaturation and purification of proteins (USRPP) had the following four functions: to completely remove denaturant, to renature proteins, to separate renatured proteins from impurities, and to easily recycle waste denaturant. The efficiencies of refolding and purification of proteins by the USRPP are almost comparable to a usual long Chromatographie column in laboratory. In preparative scale, USRPP can be easily, rapidly, and economically applied requiring a low pressure gradient. As an example, recombinant human interferon-γ is employed to elucidate the application of the preparative USRPP.
基金support from the National Natural Science Foundation of China under major research program of nanoscience and nanotechnology(Grant No.90606005)major project No.20490210,project No.20571040.
文摘This paper reports an easy and effective way to fabricate polystyrene/poly(N-isopropylacrylamide)(PS/PNIPAM)core-shell particles and PNIPAM hollow spheres.The main point of the method is to take advantage of the hydrophobic interaction between initiator and PS particles.The hydrophobic azodiisobutyronitriles automatically concentrate around the PS particles and initiate polymerization of N-isopropylacrylamide(NIPAM)and the crosslinkermethylene bisacrylamide(MBA),which dissolve in the aqueous phase,at the surface of the PS nanoparticles.Then,PNIPAM adheres to the PS particles to form a coreshell structure as a result of their hydrophobic interaction.This interaction is due to the unique property of PNIPAM,namely,its ability to transition from hydrophilic to hydrophobic when the temperature rises to 32℃.Furthermore,the hollow PNIPAM spheres were obtained by etching the PS core with chloroform.
基金This work was financially supported by the National Natural Science Foundation of China(21808133)Scientific Research Foundation for Young Scholars of Shaanxi University of Science&Technology(contract grant number 2017BT-32)+1 种基金Xianyang Science and Technology Project(Y20190138)Shaanxi Province Key R&D Program(2018ZDXM-SF-091).
文摘Peptide self-assembles with bionic properties have been widely utilized for bioactive drugs and biomedical materials.Collagen mimetic peptide(CMP)gains more attention due to its unique advantages in biosecurity and function.Unfortunately,the self-assembly mechanism of CMP,particularly the effect of intermolecular forces on its self-assembly behavior and morphology,is still unrecognized.Herein,the hydrophilic glycidol(GCD)and hydrophobic Y-glycidyl ether oxypropyl trimethoxysilane(GLH)were grafted onto the side chains of CMP through the ring-opening reaction(GCD/CMP,GLH/CMP).Subsequently,the effects of hydrophilic and hydrophobic interactions on the self-assembly behavior and morphology of CMP were further studied.The results substantiated that the GCD/CMP and GLH/CMP self-assembly followed“nucleation-growth”mechanism,and the supererogatory hydrophilic and hydrophobic groups prolonged the nucleation and growth time of CMP self-assembly.Noted that the hydrophilic interaction had stronger driving effects than hydrophobic interaction on the self-assembly of CMP.The GCD/CMP and GLH/CMP self-assembles exhibited fibrous 3D network and microsphere morphology,respectively.Furthermore,the GLH/CMP self-assembles had better resistance to degradation.Consequently,the microtopography and degradation properties of CMP self-assembles could be controlled by the hydrophilic and hydrophobic interactions between CMP,which would further provide a way for subsequent purposeful design of biomedical materials.
