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Proteomics of Skeletal Muscle: Focus on Insulin Resistance and Exercise Biology. Proteomes 2016; 4:proteomes4010006. [PMID: 28248217 PMCID: PMC5217365 DOI: 10.3390/proteomes4010006] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 01/25/2016] [Accepted: 01/28/2016] [Indexed: 12/21/2022] Open
Abstract
Skeletal muscle is the largest tissue in the human body and plays an important role in locomotion and whole body metabolism. It accounts for ~80% of insulin stimulated glucose disposal. Skeletal muscle insulin resistance, a primary feature of Type 2 diabetes, is caused by a decreased ability of muscle to respond to circulating insulin. Physical exercise improves insulin sensitivity and whole body metabolism and remains one of the most promising interventions for the prevention of Type 2 diabetes. Insulin resistance and exercise adaptations in skeletal muscle might be a cause, or consequence, of altered protein expressions profiles and/or their posttranslational modifications (PTMs). Mass spectrometry (MS)-based proteomics offer enormous promise for investigating the molecular mechanisms underlying skeletal muscle insulin resistance and exercise-induced adaptation; however, skeletal muscle proteomics are challenging. This review describes the technical limitations of skeletal muscle proteomics as well as emerging developments in proteomics workflow with respect to samples preparation, liquid chromatography (LC), MS and computational analysis. These technologies have not yet been fully exploited in the field of skeletal muscle proteomics. Future studies that involve state-of-the-art proteomics technology will broaden our understanding of exercise-induced adaptations as well as molecular pathogenesis of insulin resistance. This could lead to the identification of new therapeutic targets.
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Baydemir G, Türkoğlu EA, Andaç M, Perçin I, Denizli A. Composite cryogels for lysozyme purification. Biotechnol Appl Biochem 2014; 62:200-7. [PMID: 24923509 DOI: 10.1002/bab.1259] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Accepted: 06/06/2014] [Indexed: 11/09/2022]
Abstract
Beads-embedded novel composite cryogel was synthesized to purify lysozyme (Lyz) from chicken egg white. The poly(hydroxyethyl methacrylate-N-methacryloyl-L-phenylalanine) (PHEMAPA) beads of smaller than 5 µm size were synthesized by suspension polymerization and then embedded into a poly(hydroxyethyl methacrylate) (PHEMA)-based cryogel column. The PHEMAPA bead-embedded cryogel (BEC) column was characterized by swelling tests, scanning electron microscopy (SEM), surface area measurements by the Brunauer-Emmett-Teller (BET) method, elemental analysis, and flow dynamics. The specific surface area of the PHEMAPA BEC was found as 41.2 m(2) /g using BET measurements. Lyz-binding experiments were performed using aqueous solutions in different conditions such as initial Lyz concentration, pH, flow rate, temperature, and NaCl concentration of an aqueous medium. The PHEMAPA BEC column could be used after 10 adsorption-desorption studies without any significant loss in adsorption capacity of Lyz. The PHEMAPA BEC column was used to purify Lyz from chicken egg white, and gel electrophoresis was used to estimate the purity of Lyz. The chromatographic application of the PHEMAPA BEC column was also performed using fast protein liquid chromatography.
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Affiliation(s)
- Gözde Baydemir
- Biochemistry Division, Department of Chemistry, Hacettepe University, Ankara, Turkey
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Trace analysis of fluoxetine and its metabolite norfluoxetine. Part I: Development of a chiral liquid chromatography–tandem mass spectrometry method for wastewater samples. J Chromatogr A 2011; 1218:5587-96. [DOI: 10.1016/j.chroma.2011.06.024] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2011] [Revised: 05/25/2011] [Accepted: 06/02/2011] [Indexed: 11/17/2022]
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Lienqueo ME, Mahn A, Vásquez L, Asenjo JA. Methodology for predicting the separation of proteins by hydrophobic interaction chromatography and its application to a cell extract. J Chromatogr A 2003; 1009:189-96. [PMID: 13677659 DOI: 10.1016/s0021-9673(03)00924-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Hydrophobic interaction chromatography (HIC) is widely used in the downstream processing of proteins. Resolution of HIC is very good, but sometimes not as high as expected. Resolution values could be increased if good operating conditions were selected. In this paper we present a methodology for selecting good operating conditions. First, it is necessary to predict the dimensionless retention time (DRT) of each protein in the mixture. We use a correlation such as DRT = A + Bphi + Cphi2, where phi is the superficial hydrophobicity of the protein, which is calculated considering the hydrophobicity of the superficial amino acids using the Miyazawa-Jernigan scale. Considering that there was little interaction amongst proteins in a mixture at the concentrations investigated (2 g/l of each protein), the behaviour of the proteins in the mixture was considered to be similar to that of the individual proteins. Using simulations it was possible to test different operating conditions for the purification of a target protein from a mixture of proteins and it was possible to select ideal conditions. The methodology developed was also tested for the purification of a recombinant protein from a fermentation extract of yeast producing human superoxide dismutase and the results have been satisfactory.
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Affiliation(s)
- M Elena Lienqueo
- Centre for Biochemical Engineering and Biotechnology, Department of Chemical Engineering, Millennium Institute for Advanced Studies in Cell Biology and Biotechnology, University of Chile, Beauchef 861, Santiago, Chile.
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Kato Y, Nakamura K, Kitamura T, Moriyama H, Hasegawa M, Sasaki H. Separation of proteins by hydrophobic interaction chromatography at low salt concentration. J Chromatogr A 2002; 971:143-9. [PMID: 12350109 DOI: 10.1016/s0021-9673(02)01039-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We investigated protein separation by hydrophobic interaction chromatography (HIC) at low salt concentration on the supports of various hydrophobicities. Hydrophobic proteins could be successfully separated with more than 90% recovery by gradient elution of ammonium sulfate from 0.3-0.5 M to 0 in 50 mM phosphate buffer (pH 6.8) by using supports whose hydrophobicities were properly adjusted individually for each protein. Satisfactory results were also obtained by isocratic elution without ammonium sulfate and gradient elution of ethanol from 0 to 10%. HIC at low salt concentration was compatible with other modes of liquid chromatography like ion-exchange chromatography. On the other hand, it was not successful to separate hydrophilic proteins at low salt concentration. Recoveries of hydrophilic proteins decreased before they were retained enough as support hydrophobicity increased. Therefore, it is inevitable to use a higher concentration of salt, e.g., 1-2 M ammonium sulfate, on hydrophilic or moderately hydrophobic support in order to retain hydrophilic proteins without decrease in recovery.
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Affiliation(s)
- Yoshio Kato
- Nanyo Research Laboratory, Tosoh Corporation, Shinnanyo, Yamaguchi, Japan.
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Lina FY, Chen WY, Ruaan RC, Huang HM. Microcalorimetric studies of interactions between proteins and hydrophobic ligands in hydrophobic interaction chromatography: effects of ligand chain length, density and the amount of bound protein. J Chromatogr A 2000; 872:37-47. [PMID: 10749485 DOI: 10.1016/s0021-9673(99)01231-5] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
Using isothermal titration calorimetry (ITC), this investigation directly measured the adsorption enthalpies of proteins on various hydrophobic adsorbents. Various amounts of butyl and octyl groups were attached onto CM-Sepharose to form C4 and C8, two types of hydrophobic adsorbents. The adsorption enthalpies of both trypsinogen and alpha-chymotrypsinogen A were measured at 4.0 M NaCl and pH 10.0, in which most ionic interaction was suppressed. The adsorption isotherms of both proteins on various adsorbents were also measured, thus allowing us to calculate the Gibbs free energy and entropy of adsorption. Experimental results indicated that the adsorption of both proteins on butyl-containing adsorbents was exothermic, while their adsorption on octyl ones was endothermic. In addition, binding of both proteins with the butyl ligand is basically an adsorption process, while binding with the octyl ligand is adsorption and partition processes. Moreover, on both butyl or octyl, the adsorption enthalpy became increasingly positive as the ligand density increased, while the adsorption entropy became more positive as the alkyl chain length or density of the adsorbent increased. In addition, ITC was used to measure protein-protein interaction. The adsorption enthalpy of both proteins increased as the amount of bound protein increased, and the enthalpy increase of trypsinogen appeared to be higher than that of alpha-chymotrypsinogen A. This observation implies that protein-protein repulsion was stronger among trypsinogen molecules in the experiments.
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Affiliation(s)
- F Y Lina
- Department of Chemical Engineering, National Central University, Chung-Li, Taiwan
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Affiliation(s)
- S L Wu
- Department of Analytical Chemistry, Genentech, Inc., South San Francisco, California 94080, USA
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Lundahl P, Yang Q. Liposome chromatography: liposomes immobilized in gel beads as a stationary phase for aqueous column chromatography. J Chromatogr A 1991; 544:283-304. [PMID: 1885691 DOI: 10.1016/s0021-9673(01)83992-3] [Citation(s) in RCA: 63] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Liposomes have been used as a stationary phase for column chromatography with an aqueous mobile phase. They were immobilized in the pores of carrier gel beads by two methods: (A) hydrophobic ligands were coupled to the matrix of gel beads, which then were packed into a column and liposomes were applied and became associated with the ligands by hydrophobic interaction; and (B) phospholipids and detergent were dialysed in the presence of gel beads; many of the liposomes that formed in the pores of the beads were sterically immobilized by the gel matrix. Proteoliposomes containing red cell glucose transport protein in the lipid bilayers were immobilized in a column by method A. This column retained D-glucose longer than L-glucose. In contrast to L-glucose, D-glucose was transported into and out of the immobilized liposomes, causing an increased retention. Liposomes with (stearylamine)+ or (phosphatidylserine)- in their lipid bilayers were immobilized by method B and the gel beads were packed into a column. A protein of opposite charge was applied in excess. Under suitable conditions, the protein molecules became close-packed on the liposome surfaces. Ion-exchange chromatographic experiments with proteins showed that these sterically immobilized liposomes were also stable enough to be used as a stationary phase. The loss of lipids was 5-23% in the first run at high protein load and with sodium chloride gradient elution but was lower in subsequent runs. It is proposed that water-soluble molecules can be separated and their interactions with liposome surfaces studied by chromatography on immobilized liposomes in detergent-free aqueous solution. Membrane proteins can be inserted and ligands can be anchored in the lipid bilayers for chromatographic purposes.
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Affiliation(s)
- P Lundahl
- Department of Biochemistry, University of Uppsala, Sweden
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Rykke M, Rölla G. Effect of silicone oil on protein adsorption to hydroxyapatite in vitro and on pellicle formation in vivo. SCANDINAVIAN JOURNAL OF DENTAL RESEARCH 1990; 98:401-11. [PMID: 1963500 DOI: 10.1111/j.1600-0722.1990.tb00991.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Silicone oil has been introduced in a dentifrice for smokers because of its effect as a polishing agent. Silicone oils are hydrophobic in character and have low surface tensions and good wetting properties. Due to the low surface tension, silicone oils may spread readily on solid surfaces and cover them with a thin, water-repellent film. Introduced via dentifrices silicone oil may thus well be able to adsorb to enamel surfaces and to interfere with surface characteristics such as protein adsorption. The aim of the present study was to examine the effect of silicone oil on protein adsorption to hydroxyapatite (HA) in vitro and on pellicle formation in vivo. The effect on protein adsorption to HA in vitro was studied by adsorption of albumin to either untreated or silicone oil treated HA powders. Ion exchange chromatography was also used with either untreated or silicone oil treated HA as bed materials. The effect on pellicle formation in vivo was studied using enamel fragments carried in the mouth to acquire pellicle material. The chemical composition of the acquired pellicle was studied by collection and chemical analysis of pellicle material formed on enamel surfaces in vivo. The study showed that silicone oil treated HA took up less protein and that the adsorbed protein was bound to hydroxyapatite by a different mechanism as compared to untreated controls. The results indicated that hydrophobic interactions could be involved in binding of proteins to silicone oil treated hydroxyapatite. Silicone oil treated enamel fragments carried in the mouth showed a slower rate of pellicle formation as compared to untreated fragments. The amino acid composition of the acquired pellicle collected in vivo from silicone oil treated enamel surfaces was also different from pellicle material collected from untreated enamel.
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Affiliation(s)
- M Rykke
- Department of Operative Dentistry, Dental Faculty, University of Oslo, Norway
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Benedek K. Thermodynamics of α-lactalbumin denaturation in hydrophobic-interaction chromatography and stationary phases comparison. J Chromatogr A 1988. [DOI: 10.1016/s0021-9673(00)90556-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Influence of additives to the eluent on the hydrophobic interaction chromatography of simple compounds. J Chromatogr A 1988. [DOI: 10.1016/s0021-9673(00)90408-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Hutchens TW, Li CM, Besch PK. Proteins associated with untransformed estrogen receptor in vitro. Perturbation of hydrophobic interactions induces alterations in quaternary structure and exposure of the DNA-binding site. Biochemistry 1987; 26:5608-16. [PMID: 3676272 DOI: 10.1021/bi00392a005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Estrogen receptors from calf uteri have been analyzed by high-performance size-exclusion chromatography, chromatofocusing, and DNA affinity chromatography using conditions designed to evaluate the relative contribution of hydrophobic interactions between the steroid-binding subunit and other receptor-associated proteins. The single large (untransformed) species of soluble estrogen-receptor consistently (n = 9) found in calf uteri displayed a rapid change in Stokes radius from 8.0 to 3.5 nm upon exposure to elevated ionic strengths (0.4 M KCl). However, equilibration of the estrogen-receptor complex into urea (up to 6 M) did not dissociate the untransformed receptor into the 3.5-nm receptor form (subunit) observed in hypertonic (0.4 M KCl) buffers. Exposure to 6 M urea did result in conversion of the untransformed receptor (8.0 nm) to a 6.0-6.5-nm receptor form not previously observed in either hypotonic or hypertonic buffers. In the presence of both 6 M urea and 0.4 M KCl, the untransformed estrogen-receptor complex was converted to a smaller receptor form intermediate in apparent size (4.5-5.0 nm) to that observed in 6 M urea or 0.4 M KCl alone. The formation of this 4.5-5.0-nm receptor form was partially estrogen dependent as determined by parallel analyses of unliganded receptor in urea/KCl buffer. The urea-induced change in apparent size (8 nm to 6.0-6.5 nm) at low ionic strength was accompanied by little or no detectable change in net surface charge as determined by chromatofocusing but a complete exposure of the DNA-binding site as evidenced by nearly quantitative interaction with DNA-agarose.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- T W Hutchens
- Department of Obstetrics and Gynecology, Baylor College of Medicine, Houston, Texas 77030
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Wu SL, Figueroa A, Karger BL. Protein conformational effects in hydrophobic interaction chromatography. Retention characterization and the role of mobile phase additives and stationary phase hydrophobicity. J Chromatogr A 1986; 371:3-27. [PMID: 3558552 DOI: 10.1016/s0021-9673(01)94689-8] [Citation(s) in RCA: 126] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
We have studied the conformational behavior of alpha-lactalbumin (alpha-LACT) in hydrophobic interaction chromatography (HIC). Retention characterization in terms of Z (slope of plot of ln k' vs. ln phi B, where k' is the capacity factor and phi B is the volume fraction of mobile phase B) has been explored, and the relationship of Z to other slopes, such as S (slope of the plot of ln k' vs. phi B) has been derived. The reasons for the sensitivity of Z to conformational change are discussed. The enhanced broadening of alpha-LACT in a temperature transition region of conformational change has been studied by spectral analysis using on-line photodiode array detection. The influence of Ca2+ and Mg2+ addition to the mobile phase is further explored. Since alpha-LACT is a calcium binding protein, addition of this metal leads to stabilization, i.e. higher column temperatures are required for conformational change. On the other hand, addition of Mg2+ appears to destabilize the protein. We have explored the use of a more hydrophobic support, C2-(ethyl) ether phase, for the elution of alpha-LACT. In this case, two widely separated peaks are observed. By spectral analysis the first peak is shown to be native and the later eluted, broad second peak to be an unfolded mixture of species. As previously observed in reversed-phase liquid chromatography, the second peak grows at the expense of the first, as the column temperature is raised. The second peak also grows as the contact time of the protein with the surface increases. This behavior can be ascribed to the conformational change of alpha-LACT in the column, the late eluted species under the second peak binding significantly more strongly to the phase than the native peak. Reinjection of the late eluted fraction reveals that reformation of the native species takes place in solution within 30 min. As before, addition of Ca2+ reduces the extent of unfolding under any specific condition. These results add further to our understanding and ability to control conformational changes in high-performance liquid chromatography.
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Gradient and isocratic high-performance hydrophobic interaction chromatography of proteins on agarose columns. J Chromatogr A 1986. [DOI: 10.1016/0021-9673(86)80065-6] [Citation(s) in RCA: 83] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Hjertén S, Yao K, Liu ZQ, Yang D, Wu BL. Simple method to prepare non-charged, amphiphilic agarose derivatives, for instance for hydrophobic interaction chromatography. J Chromatogr A 1986. [DOI: 10.1016/s0021-9673(01)87022-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Rozgonyi F, Szitha KR, Hjertén S, Wadström T. Standardization of salt aggregation test for reproducible determination of cell-surface hydrophobicity with special reference to Staphylococcus species. THE JOURNAL OF APPLIED BACTERIOLOGY 1985; 59:451-7. [PMID: 3910635 DOI: 10.1111/j.1365-2672.1985.tb03345.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The laboratory conditions for reproducible routine determination of staphylococcal cell-surface hydrophobicity by the salt aggregation test were standardized. Fresh bacterial suspensions standardized to 5 x 10(9) cfu/ml gave the most reproducible results with both Staphylococcus aureus and coagulase-negative staphylococci. For relatively hydrophobic strains a 5-min reading time was necessary to detect bacterial aggregation in ammonium sulphate solutions ranging from 0.1 M to 1.5 M, pH 6.8. A x 10 hand lens facilitated reading aggregations. Overnight storage of bacterial suspensions at 20 degrees C reduced cell-surface hydrophobicity of all species, while storage at 4 degrees C reduced the hydrophobic nature of Staph. aureus strains. The hydrophobicity of coagulase-negative staphylococci rarely changed at 4 degrees C. A 10-fold dilution of fresh, standardized bacterial suspensions made it impossible to detect bacterial aggregation in ammonium sulphate solutions even with a hand lens. Under standardized conditions three types of staphylococcal cell aggregations were observed. The first looked like the slide agglutination for O antigens of Enterobacteriaceae, the second resembled H-agglutination, while the third had a filamentous appearance. These patterns indicated that more than one component might contribute to cell-surface hydrophobicity of both Staph. aureus and coagulase-negative staphylococci, or the same component might have different position on the cell surface.
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Allenmark S, Bomgren B, Borén H. Direct liquid chromatographic separation of enantiomers on immobilized protein stationary phases. IV. Molecular interaction forces and retention behaviour in chromatography on bovine serum albumin as a stationary phase. J Chromatogr A 1984; 316:617-24. [PMID: 6530428 DOI: 10.1016/s0021-9673(00)96187-9] [Citation(s) in RCA: 102] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Chromatography with the use of immobilized bovine serum albumin as a stationary phase and aqueous buffer systems as eluents has proved to be a highly selective method, capable of separating structurally very closely related compounds. Retention can be effectively regulated by changes in at least three independent parameters of the mobile phase, which may be used for an optimization of separation factors. Particularly, the enantioselective properties of the chiral stationary phase have been demonstrated to be useful for the analytical resolution of a variety of racemates into enantiomers. From the variation of the retention behaviour with substituent effects, as well as the mobile phase composition, some indications regarding the molecular interaction forces regulating the substrate-protein equilibria have been obtained.
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Bontemps J, Bettendorff L, Lombet J, Grandfils C, Dandrifosse G, Schoffeniels E, Nevejans F, Crommen J. Poly(styrene—divinylbenzene) as reversed-phase adsorbent for the high-performance liquid chromatographic analysis of thiochrome derivatives of thiamine and phosphorylated esters. J Chromatogr A 1984. [DOI: 10.1016/s0021-9673(01)87651-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Allenmark S, Bomgren B, Borén H. Direct liquid chromatographic separation of enantiomers on immobilized protein stationary phases. J Chromatogr A 1983. [DOI: 10.1016/s0021-9673(01)95006-x] [Citation(s) in RCA: 216] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Nilsson T, Wiman B. Purification and characterization of human C1-esterase inhibitor. BIOCHIMICA ET BIOPHYSICA ACTA 1982; 705:271-6. [PMID: 6981429 DOI: 10.1016/0167-4838(82)90188-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
A new purification method for C1-esterase inhibitor is described, which is essentially a three-step procedure: precipitation with poly(ethylene glycol), chromatography on DEAE-cellulose and hydrophobic interaction chromatography on hexyl-Sepharose. The final product is a single-chain glycoprotein with a molecular weight of about 100 000 and NH2-terminal asparagine. The molecule is fully active as judged by complex formation with C1s. Two of its three disulphide bridges can be easily reduced and S-carboxymethylated under non-denaturing conditions without loss of activity. However, at high dithioerythritol concentration the third disulphide bridge is also cleaved and accompanied by loss of the activity, indicating that this disulphide bridge is involved in maintaining the conformation around the reactive site in the inhibitor.
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Lindahl M, Faris A, Wadström T, Hjertén S. A new test based on 'salting out' to measure relative surface hydrophobicity of bacterial cells. BIOCHIMICA ET BIOPHYSICA ACTA 1981; 677:471-6. [PMID: 7028137 DOI: 10.1016/0304-4165(81)90261-0] [Citation(s) in RCA: 335] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
A simple method for quantification of the hydrophobic surface properties of bacteria is described. The method is based on precipitation of cells by salts, for instance (NH4)2SO4. The order in which cells are precipitated is a measure of their surface hydrophobicities, the most hydrophobic cells being first precipitated at low salt concentration. Temperature, pH, time and the bacterial cell concentration were shown to affect the results. When these variables were kept constant the method was highly reproducible. This 'salting out' method was applied to enterotoxigenic Escherichia coli strains with different surface protein antigens (fimbriae, fibrillae and colonization factor antigen, CFA). These enterotoxigenic E. coli strains were found to have surface hydrophobicity in the following order: CFA/I greater than CFA/II greater than K88 similar to K99 greater than type 1.
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