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Hamark C, Pendrill R, Landström J, Dotson Fagerström A, Sandgren M, Ståhlberg J, Widmalm G. Enantioselective Binding of Propranolol and Analogues Thereof to Cellobiohydrolase Cel7A. Chemistry 2018; 24:17975-17985. [PMID: 30255965 DOI: 10.1002/chem.201803104] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Indexed: 12/28/2022]
Abstract
At the catalytic site for the hydrolysis of cellulose the enzyme cellobiohydrolase Cel7A binds the enantiomers of the adrenergic beta-blocker propranolol with different selectivity. Methyl-to-hydroxymethyl group modifications of propranolol, which result in higher affinity and improved selectivity, were herein studied by 1 H,1 H and 1 H,13 C scalar spin-spin coupling constants as well as utilizing the nuclear Overhauser effect (NOE) in conjunction with molecular dynamics simulations of the ligands per se, which showed the presence of all-antiperiplanar conformations, except for the one containing a vicinal oxygen-oxygen arrangement governed by the gauche effect. For the ligand-protein complexes investigated by NMR spectroscopy using, inter alia, transferred NOESY and saturation-transfer difference (STD) NMR experiments the S-isomers were shown to bind with a higher affinity and a conformation similar to that preferred in solution, in contrast to the R-isomer. The fact that the S-form of the propranolol enantiomer is pre-arranged for binding to the protein is also observed for a crystal structure of dihydroxy-(S)-propranolol and Cel7A presented herein. Whereas the binding of propranolol is entropy driven, the complexation with the dihydroxy analogue is anticipated to be favored also by an enthalpic term, such as for its enantiomer, that is, dihydroxy-(R)-propranolol, because hydrogen-bond donation replaces the corresponding bonding from hydroxyl groups in glucosyl residues of the natural substrate. In addition to a favorable entropy component, albeit lesser in magnitude, this represents an effect of enthalpy-to-entropy compensation in ligand-protein interactions.
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Affiliation(s)
- Christoffer Hamark
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, 10691, Stockholm, Sweden
| | - Robert Pendrill
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, 10691, Stockholm, Sweden
| | - Jens Landström
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, 10691, Stockholm, Sweden
| | | | - Mats Sandgren
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, P.O. Box 7015, 75007, Uppsala, Sweden
| | - Jerry Ståhlberg
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, P.O. Box 7015, 75007, Uppsala, Sweden
| | - Göran Widmalm
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, 10691, Stockholm, Sweden
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Poshina DN, Raik SV, Poshin AN, Skorik YA. Accessibility of chitin and chitosan in enzymatic hydrolysis: A review. Polym Degrad Stab 2018. [DOI: 10.1016/j.polymdegradstab.2018.09.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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3
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Abstract
The development of separation methods for the analysis and resolution of chiral drugs and solutes has been an area of ongoing interest in pharmaceutical research. The use of proteins as chiral binding agents in high-performance liquid chromatography (HPLC) has been an approach that has received particular attention in such work. This report provides an overview of proteins that have been used as binding agents to create chiral stationary phases (CSPs) and in the use of chromatographic methods to study these materials and protein-based chiral separations. The supports and methods that have been employed to prepare protein-based CSPs will also be discussed and compared. Specific types of CSPs that are considered include those that employ serum transport proteins (e.g., human serum albumin, bovine serum albumin, and alpha1-acid glycoprotein), enzymes (e.g., penicillin G acylase, cellobiohydrolases, and α-chymotrypsin) or other types of proteins (e.g., ovomucoid, antibodies, and avidin or streptavidin). The properties and applications for each type of protein and CSP will also be discussed in terms of their use in chromatography and chiral separations.
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Affiliation(s)
- Cong Bi
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0304, USA
| | - Xiwei Zheng
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0304, USA
| | - Shiden Azaria
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0304, USA
| | - Sandya Beeram
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0304, USA
| | - Zhao Li
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0304, USA
| | - David S. Hage
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0304, USA
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Camacho-Muñoz D, Petrie B, Castrignanò E, Kasprzyk-Hordern B. Enantiomeric Profiling of Chiral Pharmacologically Active Compounds in the Environment with the Usage of Chiral Liquid Chromatography
Coupled with Tandem Mass Spectrometry. CURR ANAL CHEM 2016; 12:303-314. [PMID: 27713682 PMCID: PMC5024650 DOI: 10.2174/1573411012666151009195039] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Revised: 06/30/2015] [Accepted: 06/30/2015] [Indexed: 11/29/2022]
Abstract
The issue of drug chirality is attracting increasing attention among the scientific community. The phenomenon of chirality has been overlooked in environmental research (environmental occurrence, fate and toxicity) despite the great impact that chiral pharmacologically active compounds (cPACs) can provoke on ecosystems. The aim of this paper is to introduce the topic of chirality and its implications in environmental contamination. Special attention has been paid to the most recent advances in chiral analysis based on liquid chromatography coupled with mass spectrometry and the most popular protein based chiral stationary phases. Several groups of cPACs of environmental relevance, such as illicit drugs, human and veterinary medicines were discussed. The increase in the number of papers published in the area of chiral environmental analysis indicates that researchers are actively pursuing new opportunities to provide better understanding of environmental impacts resulting from the enantiomerism of cPACs.
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Affiliation(s)
| | - Bruce Petrie
- Department of Chemistry, University of Bath, Bath, United Kingdom
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Matsunaga H, Haginaka J. Separation of enantiomers on chiral stationary phase based on cellulase: Effect of preparation method and silica particle diameters on chiral recognition ability. J Chromatogr A 2016; 1467:155-162. [PMID: 27266335 DOI: 10.1016/j.chroma.2016.05.069] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Revised: 05/19/2016] [Accepted: 05/20/2016] [Indexed: 10/21/2022]
Abstract
Cellulase (Cel) was immobilized onto aminopropyl-silica gels via its amino and carboxy groups, respectively, using N,N'-disuccinimidyl carbonate, and 1-ethyl-3-(3'-dimethylaminopropyl)carbodimide and N-hydroxysulfosuccinimide. They were termed N-Cel and C-Cel, respectively. Despite their smaller retention factors on a C-Cel column, the enantioseparation factors and resolution of β-blockers, propranolol, alprenolol, oxprenolol and pindolol, were similar with N- and C-Cel columns. In addition, C-Cel was prepared using aminopropyl-silica gels, whose nominal particle diameters were 5 and 3, and 2.1μm, respectively. A C-Cel column prepared with 2.1-μm aminopropyl-silica gels gave the highest enantioselectivity and column efficiency among three C-Cel columns. Furthermore, the influence of N,N-dimethyl-n-octylamine (DMOA) or cellobiose concentrations on the retentivity and enantioselectivity for β-blockers on a C-Cel column was investigated. The results indicate that single-site competition of β-blockers with DMOA or cellobiose on the catalytic binding site of Cel and the further bindings at the secondary site in a non-competitive fashion could occur. Furthermore, the enantioselective bindings of β-blockers could occur at the catalytic biding cite of Cel and at the secondary binding site.
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Affiliation(s)
- Hisami Matsunaga
- School of Pharmacy and Pharmaceutical Sciences, Mukogawa Women's University, 11-68, Koshien Kyuban-cho, Nishinomiya 663-8179, Japan
| | - Jun Haginaka
- School of Pharmacy and Pharmaceutical Sciences, Mukogawa Women's University, 11-68, Koshien Kyuban-cho, Nishinomiya 663-8179, Japan.
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Ali L, Flowers SA, Jin C, Bennet EP, Ekwall AKH, Karlsson NG. The O-glycomap of lubricin, a novel mucin responsible for joint lubrication, identified by site-specific glycopeptide analysis. Mol Cell Proteomics 2014; 13:3396-409. [PMID: 25187573 PMCID: PMC4256492 DOI: 10.1074/mcp.m114.040865] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Revised: 08/15/2014] [Indexed: 11/06/2022] Open
Abstract
The lubricative, heavily glycosylated mucin-like synovial glycoprotein lubricin has previously been observed to contain glycosylation changes related to rheumatoid and osteoarthritis. Thus, a site-specific investigation of the glycosylation of lubricin was undertaken, in order to further understand the pathological mechanisms involved in these diseases. Lubricin contains an serine/threonine/proline (STP)-rich domain composed of imperfect tandem repeats (EPAPTTPK), the target for O-glycosylation. In this study, using a liquid chromatography-tandem mass spectrometry approach, employing both collision-induced and electron-transfer dissociation fragmentation methods, we identified 185 O-glycopeptides within the STP-rich domain of human synovial lubricin. This showed that adjacent threonine residues within the central STP-rich region could be simultaneously and/or individually glycosylated. In addition to core 1 structures responsible for biolubrication, core 2 O-glycopeptides were also identified, indicating that lubricin glycosylation may have other roles. Investigation of the expression of polypeptide N-acetylgalactosaminyltransferase genes was carried out using cultured primary fibroblast-like synoviocytes, a cell type that expresses lubricin in vivo. This analysis showed high mRNA expression levels of the less understood polypeptide N-acetylgalactosaminyltransferase 15 and 5 in addition to the ubiquitously expressed polypeptide N-acetylgalactosaminyltransferase 1 and 2 genes. This suggests that there is a unique combination of transferase genes important for the O-glycosylation of lubricin. The site-specific glycopeptide analysis covered 82% of the protein sequence and showed that lubricin glycosylation displays both micro- and macroheterogeneity. The density of glycosylation was shown to be high: 168 sites of O-glycosylation, predominately sialylated, were identified. These glycosylation sites were focused in the central STP-rich region, giving the domain a negative charge. The more positively charged lysine and arginine residues in the N and C termini suggest that synovial lubricin exists as an amphoteric molecule. The identification of these unique properties of lubricin may provide insight into the important low-friction lubricating functions of lubricin during natural joint movement.
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Affiliation(s)
- Liaqat Ali
- From the ‡Department of Medical Biochemistry, Institute of Biomedicine, University of Gothenburg, Box 440, Medicinaregatan 9A, 405 30, Gothenburg, Sweden
| | - Sarah A Flowers
- From the ‡Department of Medical Biochemistry, Institute of Biomedicine, University of Gothenburg, Box 440, Medicinaregatan 9A, 405 30, Gothenburg, Sweden
| | - Chunsheng Jin
- From the ‡Department of Medical Biochemistry, Institute of Biomedicine, University of Gothenburg, Box 440, Medicinaregatan 9A, 405 30, Gothenburg, Sweden
| | - Eric Paul Bennet
- §Department of Odontology, Copenhagen Center for Glycomics, University of Copenhagen, Norre Alle 20, DK-2200 Copenhagen N, Denmark
| | - Anna-Karin H Ekwall
- ¶Department of Rheumatology and Inflammation Research, Institute of Medicine, University of Gothenburg, Guldhedsgatan 10A, SE-41346, Gothenburg, Sweden
| | - Niclas G Karlsson
- From the ‡Department of Medical Biochemistry, Institute of Biomedicine, University of Gothenburg, Box 440, Medicinaregatan 9A, 405 30, Gothenburg, Sweden;
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Ikeda Y, Parashar A, Bressler DC. Highly retained enzymatic activities of two different cellulases immobilized on non-porous and porous silica particles. BIOTECHNOL BIOPROC E 2014. [DOI: 10.1007/s12257-014-0191-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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8
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Wu M, Nerinckx W, Piens K, Ishida T, Hansson H, Sandgren M, Ståhlberg J. Rational design, synthesis, evaluation and enzyme-substrate structures of improved fluorogenic substrates for family 6 glycoside hydrolases. FEBS J 2012; 280:184-98. [DOI: 10.1111/febs.12060] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Revised: 10/31/2012] [Accepted: 11/05/2012] [Indexed: 11/29/2022]
Affiliation(s)
- Miao Wu
- Department of Molecular Biology; Swedish University of Agricultural Sciences; Uppsala; Sweden
| | - Wim Nerinckx
- Laboratory for Protein Biochemistry and Biomolecular Engineering; Department of Biochemistry and Microbiology; University of Gent; Gent; Belgium
| | | | - Takuya Ishida
- Department of Molecular Biology; Swedish University of Agricultural Sciences; Uppsala; Sweden
| | - Henrik Hansson
- Department of Molecular Biology; Swedish University of Agricultural Sciences; Uppsala; Sweden
| | - Mats Sandgren
- Department of Molecular Biology; Swedish University of Agricultural Sciences; Uppsala; Sweden
| | - Jerry Ståhlberg
- Department of Molecular Biology; Swedish University of Agricultural Sciences; Uppsala; Sweden
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A simple and fast method for the determination of endo- and exo-cellulase activity in cellulase preparations using filter paper. Enzyme Microb Technol 2012; 51:280-5. [DOI: 10.1016/j.enzmictec.2012.07.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Revised: 06/22/2012] [Accepted: 07/23/2012] [Indexed: 11/17/2022]
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10
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Analysis of the saccharification capability of high-functional cellulase JN11 for various pretreated biomasses through a comparison with commercially available counterparts. J Ind Microbiol Biotechnol 2012; 39:1741-9. [PMID: 23053344 DOI: 10.1007/s10295-012-1195-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Accepted: 08/29/2012] [Indexed: 10/27/2022]
Abstract
Although the capabilities of Trichoderma reesei cellulases have been greatly improved, these enzymes are still too costly for commercial use. The aim of this research was to assess the biomass saccharification capability of JN11, a recombinant cellulase, compared with that of the commercially available cellulases Accellerase 1500 and Cellic CTec. The activities of JN11, Accellerase 1500, and Cellic CTec were compared by using various types of cellulosic biomass, including rice straw, Erianthus, eucalyptus, and Japanese cedar. JN11 had higher saccharification capability for rice straw, Erianthus, eucalyptus, and Japanese cedar compared with the commercial cellulases. The JN11 saccharification of cellulosic biomasses, including hemicellulose (NaOH-pretreated biomasses), resulted in high glucose and xylose yields because of the high xylanase/xylosidase activity of JN11. Moreover, even JN11 saccharification of hemicellulose-free biomasses (sulfuric acid-, hydrothermally, and steam exploded-pretreated biomasses) resulted in high glucose yields. The cellulase activity of JN11, however, was comparable to that of its commercial counterparts. These findings indicate that the saccharification ability of cellulase is unrelated to its cellulase activity when measured against Avicel, CMC, pNP-lactoside, and other substrates. JN11 showed high activity for all types of pretreated cellulosic biomasses, indicating its usefulness for saccharification of various cellulosic biomasses.
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11
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Ye Z, Lane AN, Willing GA, Berson RE. Scaled-up separation of cellobiohydrolase1 from a cellulase mixture by ion-exchange chromatography. Biotechnol Prog 2011; 27:1644-52. [DOI: 10.1002/btpr.696] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Revised: 04/27/2011] [Indexed: 11/10/2022]
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12
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Human DBS sampling with LC–MS/MS for enantioselective determination of metoprolol and its metabolite O-desmethyl metoprolol. Bioanalysis 2010; 2:1437-48. [DOI: 10.4155/bio.10.107] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
>Background: The dried blood spots (DBS) sampling technique has been gaining wide interest in preclinical and clinical studies due to its inherent advantages. However, the impact of DBS sampling on chiral compounds in terms of stability and detection sensitivity has not been studied yet. Results: A high-throughput, sensitive and enantioselective LC–MS/MS-based bioanalytical method was developed and validated for the simultaneous determination of individual enantiomers of metoprolol and its metabolite O-desmethylmetoprolol (O-DMM)in human whole blood using the DBS sampling technique. Conclusions: The developed DBS LC–MS/MS assay has a run time of 3 min, shorter than all previous methods while achieving complete baseline separation of enantiomeric metoprolol and O-DMM. This study demonstrates the applicability of DBS for chiral molecules analysis.
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13
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Using supported liquid extraction together with cellobiohydrolase chiral stationary phases-based liquid chromatography with tandem mass spectrometry for enantioselective determination of acebutolol and its active metabolite diacetolol in spiked human plasma. J Chromatogr B Analyt Technol Biomed Life Sci 2009; 877:173-80. [DOI: 10.1016/j.jchromb.2008.12.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2008] [Revised: 12/01/2008] [Accepted: 12/02/2008] [Indexed: 10/21/2022]
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14
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Peri S, Karra S, Lee YY, Karim MN. Modeling Intrinsic Kinetics of Enzymatic Cellulose Hydrolysis. Biotechnol Prog 2008; 23:626-37. [PMID: 17465526 DOI: 10.1021/bp060322s] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A multistep approach was taken to investigate the intrinsic kinetics of the cellulase enzyme complex as observed with hydrolysis of noncrystalline cellulose (NCC). In the first stage, published initial rate mechanistic models were built and critically evaluated for their performance in predicting time-course kinetics, using the data obtained from enzymatic hydrolysis experiments performed on two substrates: NCC and alpha-cellulose. In the second stage, assessment of the effect of reaction intermediates and products on intrinsic kinetics of enzymatic hydrolysis was performed using NCC hydrolysis experiments, isolating external factors such as mass transfer effects, physical properties of substrate, etc. In the final stage, a comprehensive intrinsic kinetics mechanism was proposed. From batch experiments using NCC, the time-course data on cellulose, cello-oligosaccharides (COS), cellobiose, and glucose were taken and used to estimate the parameters in the kinetic model. The model predictions of NCC, COS, cellobiose, and glucose profiles show a good agreement with experimental data generated from hydrolysis of different initial compositions of substrate (NCC supplemented with COS, cellobiose, and glucose). Finally, sensitivity analysis was performed on each model parameter; this analysis provides some insights into the yield of glucose in the enzymatic hydrolysis. The proposed intrinsic kinetic model parametrized for dilute cellulose systems forms a basis for modeling the complex enzymatic kinetics of cellulose hydrolysis in the presence of limiting factors offered by substrate and enzyme characteristics.
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Affiliation(s)
- Suma Peri
- Department of Chemical Engineering, Texas Tech University, Lubbock, Texas, USA
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15
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Enantioselective determination of alprenolol in human plasma by liquid chromatography with tandem mass spectrometry using cellobiohydrolase chiral stationary phases. J Chromatogr B Analyt Technol Biomed Life Sci 2008; 872:121-7. [DOI: 10.1016/j.jchromb.2008.07.022] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2008] [Revised: 07/09/2008] [Accepted: 07/18/2008] [Indexed: 11/21/2022]
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16
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Wang L, Zhang Y, Gao P. A novel function for the cellulose binding module of cellobiohydrolase I. ACTA ACUST UNITED AC 2008; 51:620-9. [PMID: 18622745 DOI: 10.1007/s11427-008-0088-3] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2007] [Accepted: 05/21/2008] [Indexed: 11/29/2022]
Abstract
A homogeneous cellulose-binding module (CBM) of cellobiohydrolase I (CBHI) from Trichoderma pseudokoningii S-38 was obtained by the limited proteolysis with papain and a series of chromatographs filtration. Analysis of FT-IR spectra demonstrated that the structural changes result from a weakening and splitting of the hydrogen bond network in cellulose by the action of CBM(CBHI) at 40 degrees C for 24 h. The results of molecular dynamic simulations are consistent with the experimental conclusions, and provide a nanoscopic view of the mechanism that strong and medium H-bonds decreased dramatically when CBM was bound to the cellulose surface. The function of CBM(CBHI) is not only limited to locating intact CBHI in close proximity with cellulose fibrils, but also is involved in the structural disruption at the fibre surface. The present studies provided considerable evidence for the model of the intramolecular synergy between the catalytic domain and their CBMs.
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Affiliation(s)
- Lushan Wang
- State Key Laboratory of Microbial Technology, Shandong University, Jinan, 250100, China
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Burapatana V, Booth EA, Snyder IM, Prokop A, Tanner RD. A proposed mechanism for detergent-assisted foam fractionation of lysozyme and cellulase restored with beta-cyclodextrin. Appl Biochem Biotechnol 2008; 137-140:777-91. [PMID: 18478434 DOI: 10.1007/s12010-007-9097-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Foam fractionation by itself cannot effectively concentrate hydrophilic proteins such as lysozyme and cellulase. However, the addition of a detergent to a protein solution can increase the foam volume, and thus, the performance of the foam fractionation process. In this article, we propose a possible protein concentration mechanism of this detergent-assisted foam fractionation: A detergent binds to an oppositely charged protein, followed by the detergent-protein complex being adsorbed onto a bubble during aeration. The formation of this complex is inferred by a decrease in surface tension of the detergent-protein solution. The surface tension of a solution with the complex is lower than the surface tension of a protein or a detergent solution alone. The detergent can then be stripped from the adsorbed protein, such as cellulase, by an artificial chaperone such as beta-cyclodextrin. Stripping the detergent from the protein allows the protein to return to its original conformation and to potentially retain all of its original activity following the foam fractionation process. Low-cost alternatives to beta-cyclodextrin such as corn dextrin were tested experimentally to restore the protein activity through detergent stripping, but without success.
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Affiliation(s)
- Vorakan Burapatana
- Chemical Engineering Department, Vanderbilt University, Nashville, TN 37235, USA
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18
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Felix G, Berthod A. Commercial Chiral Stationary Phases for the Separations of Clinical Racemic Drugs. SEPARATION AND PURIFICATION REVIEWS 2007. [DOI: 10.1080/15422110701826997] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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19
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Arnell R, Ferraz N, Fornstedt T. Analytical characterization of chiral drug-protein interactions: comparison between the optical biosensor (surface plasmon resonance) assay and the HPLC perturbation method. Anal Chem 2007; 78:1682-9. [PMID: 16503623 DOI: 10.1021/ac051802l] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Two modern, fundamentally different methods were used for a detailed investigation of enantioselective drug-protein interactions, a surface plasmon resonance (SPR)-based Biacore 2000 biosensor assay and the previously validated HPLC perturbation method (HPLC-PM). This is the first time SPR has been used for this purpose. The fundamental features of the two methods were investigated, and the consequences for operation and data evaluation were addressed. With HPLC-PM, chiral data could be obtained directly from the racemic mixture, whereas a separate analysis of each pure enantiomer was required to obtain chiral data with SPR. It was shown that if chirality is not attributed in the SPR analysis, misleading average racemic binding constants will be obtained. Both drug and protein consumption were considerably higher with HPLC-PM. HPLC-PM was found to be best suited for measurements of weak affinity interactions, whereas the SPR method was best for strong interactions. With both methods, the presence of DMSO in the samples severely affected the interactions, introducing errors. The binding of the beta-blockers alprenolol and propranolol to Cel7a cellulase was used as a model system. These methods gave results that agreed quite well qualitatively, but considerable quantitative deviations were sometimes obtained.
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Affiliation(s)
- Robert Arnell
- Department of Surface Biotechnology, Uppsala University, BMC Box 577, SE-751 23, Uppsala, Sweden
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Pellati F, Benvenuti S. Chromatographic and electrophoretic methods for the analysis of phenethylamine [corrected] alkaloids in Citrus aurantium. J Chromatogr A 2007; 1161:71-88. [PMID: 17582424 DOI: 10.1016/j.chroma.2007.05.097] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2007] [Revised: 04/02/2007] [Accepted: 05/24/2007] [Indexed: 10/23/2022]
Abstract
Citrus aurantium (bitter orange) is a plant belonging to the family Rutaceae, whose fruit extracts have been used recently for the treatment of obesity. The most important biologically active constituents of the C. aurantium fruits are phenethylamine alkaloids (i.e. octopamine, synephrine, tyramine, N-methyltyramine and hordenine). Synephrine is a primary synthesis compound with pharmacological activities such as vasoconstriction, elevation of blood pressure and relaxation of bronchial muscle. Synephrine is present in the peel and the edible part of Citrus fruit. Of the adrenergic amines of natural origin, synephrine has been found to be the main constituent of C. aurantium fruits and extracts; the other alkaloids are either absent or present in only low concentrations. It is known that synephrine and the other amines found in C. aurantium have adverse effects on the cardiovascular system, owing to adrenergic stimulation. In light of the great commercial proliferation of C. aurantium herbal medicines in recent years, this review provides an overview of various extraction, separation and detection techniques employed for the qualitative and quantitative determination of the alkaloids in C. aurantium and related species. The application of chromatographic and electrophoretic methods for the separation and determination of these active components in C. aurantium plant material and derivatives are described. Since synephrine is a chiral compound, enantioselective chromatographic and electrophoretic techniques for the analysis of synephrine enantiomers in natural products are presented. Furthermore, examples of identification of these active compounds in complex matrices by hyphenated methods, such as gas chromatography-mass spectrometry and high-performance liquid chromatography-mass spectrometry, are described. The advantages and limitations of these separation and identification methods are assessed and discussed.
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Affiliation(s)
- Federica Pellati
- Department of Pharmaceutical Sciences, University of Modena and Reggio Emilia, Via G. Campi 183, 41100 Modena, Italy.
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Fagerström A, Nilsson M, Berg U, Isaksson R. pH dependency of ligand binding to cellobiohydrolase 1 (Cel7A). J Chromatogr A 2007; 1138:276-83. [PMID: 17141791 DOI: 10.1016/j.chroma.2006.10.098] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2006] [Revised: 10/16/2006] [Accepted: 10/19/2006] [Indexed: 11/23/2022]
Abstract
The affinity and enantioselectivity have been determined for designed propranolol derivatives as ligands for Cel7A by capillary electrophoresis (CE) at pH 7.0. These results have been compared to measurements at pH 5.0. In agreement with previous studies, the affinity increased at the higher pH. However, the affinity was not as dependent of the ligand structure at pH 7.0 as at pH 5.0, and the selectivity was generally decreased. Instead, at pH 7.0, the changes in binding were mainly dependent on the presence of additional dihydroxyl groups, indicating an increased importance of the electrostatic interactions. To evaluate the pH dependent variations in binding, changes in both the ligand and in the enzyme had to be taken into account. To ensure that the ligands had the same charge in all measurements, pKa-values of all compounds were determined. The ligand-protein interaction has also been studied by inhibition experiments at both pHs to evaluate the specific binding to the active site when competing with the substrate p-nitrophenyl lactoside (pNPL). With support of docking computations we propose a hypothesis on the effect of the ligand structure and pH dependency of the binding and selectivity of amino alcohols to Cel7A.
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Affiliation(s)
- Alexandra Fagerström
- Organic Chemistry, Department of Chemistry, P.O. Box 124, Lund University, S-221 00 Lund, Sweden
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22
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Reetz MT, Wang LW, Bocola M. Directed Evolution of Enantioselective Enzymes: Iterative Cycles of CASTing for Probing Protein-Sequence Space. Angew Chem Int Ed Engl 2006. [DOI: 10.1002/ange.200502746] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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23
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Reetz MT, Wang LW, Bocola M. Directed Evolution of Enantioselective Enzymes: Iterative Cycles of CASTing for Probing Protein-Sequence Space. Angew Chem Int Ed Engl 2006; 45:1236-41. [PMID: 16411254 DOI: 10.1002/anie.200502746] [Citation(s) in RCA: 272] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Manfred T Reetz
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim/Ruhr, Germany.
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24
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Fagerström A, Nilsson M, Berg U, Isaksson R. New propranolol analogues: binding and chiral discrimination by cellobiohydrolase Cel7A. Org Biomol Chem 2006; 4:3067-76. [PMID: 16886073 DOI: 10.1039/b605603b] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Novel propranolol analogues have been designed and synthesised and their enantioselective binding to the cellulose degrading enzyme, Cel7A, has been evaluated. Affinity and enantioselectivity have been determined by capillary electrophoresis experiments. Ligands with significantly improved affinity and selectivity have been obtained and an analysis of the results has led to insights concerning the relation between the changes in ligand structure and selectivity as well as affinity to the protein.
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Affiliation(s)
- Alexandra Fagerström
- Organic Chemistry, Department of Chemistry, P.O. Box 124, Lund University, S-221 00, Lund, Sweden
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25
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Zhang YHP, Lynd LR. Toward an aggregated understanding of enzymatic hydrolysis of cellulose: noncomplexed cellulase systems. Biotechnol Bioeng 2005; 88:797-824. [PMID: 15538721 DOI: 10.1002/bit.20282] [Citation(s) in RCA: 883] [Impact Index Per Article: 46.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Information pertaining to enzymatic hydrolysis of cellulose by noncomplexed cellulase enzyme systems is reviewed with a particular emphasis on development of aggregated understanding incorporating substrate features in addition to concentration and multiple cellulase components. Topics considered include properties of cellulose, adsorption, cellulose hydrolysis, and quantitative models. A classification scheme is proposed for quantitative models for enzymatic hydrolysis of cellulose based on the number of solubilizing activities and substrate state variables included. We suggest that it is timely to revisit and reinvigorate functional modeling of cellulose hydrolysis, and that this would be highly beneficial if not necessary in order to bring to bear the large volume of information available on cellulase components on the primary applications that motivate interest in the subject.
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26
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Pellati F, Benvenuti S, Melegari M. Enantioselective LC analysis of synephrine in natural products on a protein-based chiral stationary phase. J Pharm Biomed Anal 2005; 37:839-49. [PMID: 15862657 DOI: 10.1016/j.jpba.2004.09.008] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2004] [Revised: 09/03/2004] [Accepted: 09/06/2004] [Indexed: 11/21/2022]
Abstract
An enantioselective LC method with photodiode array detection (PAD) was developed for the enantioseparation of (+/-)-synephrine from C. aurantium L. var. amara fruits and phytotherapic derivatives by using a protein-based chiral stationary phase with cellobiohydrolase as the chiral selector (Chiral-CBH). Analyses were carried out on a Chiral-CBH column (100x4.0 mm i.d., 5 microm), with a mobile phase consisting of 2-propanol (5%, w/w) in sodium phosphate buffer (pH 6.0; 10 mM) and disodium EDTA (50 microM). The flow rate was 0.8 mL/min. Detection was set at 225 nm. To identify the order of elution, the racemate was resolved by the preparation of suitable diastereoisomeric salts with antipodes of appropriate organic acids. Isolation of synephrine from C. aurantium fruits and phytoproducts was performed by solid-phase extraction (SPE) with a strong cation-exchange phase. The method developed was validated and was found to be linear in the 0.40-40.14 microg/mL range (r2=1.000, P<0.0001) for both synephrine enantiomers. The limit of detection (LOD) for each enantiomer was 0.04 microg/mL. The limit of quantification (LOQ) for each enantiomer was 0.13 microg/mL. Intra-day precision (calculated as %R.S.D.) ranged from 0.03 to 0.24% for (-)-synephrine and from 0.03 to 0.35% for (+)-synephrine. Inter-day precision (calculated as %R.S.D.) ranged from 0.07 to 1.45% for (-)-synephrine and from 0.06 to 1.26% for (+)-synephrine. Intra- and inter-day accuracies (calculated as %recovery) were in the ranges of 97.4-100.6 and 98.0-101.6% for (-)-synephrine, and in the ranges 97.0-101.5 and 98.1-102.8% for (+)-synephrine. The results of the application of the method to the analysis of C. aurantium samples showed that (-)-synephrine was the main component. (+)-Synephrine was not detected in C. aurantium fruits and was present in low concentration in the phytoproducts.
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Affiliation(s)
- Federica Pellati
- Department of Pharmaceutical Sciences, University of Modena and Reggio Emilia, Via G. Campi 183, 41100 Modena, Italy.
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27
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Choi SO, Lee SH, Choo HYP. Prediction on the chiral behaviors of drugs with amine moiety on the chiral cellobiohydrolase stationary phase using a partial least square method. Arch Pharm Res 2004; 27:1009-15. [PMID: 15554255 DOI: 10.1007/bf02975422] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Quantitative Structure-Resolution Relationship (QSRR) using the Comparative Molecular Field Analysis (CoMFA) software was applied to predict the chromatographic behaviors of chiral drugs with an amine moiety on the chiral cellobiohydrolase (CBH) columns. As a result of the Quantitative CoMFA-Resolution Relationship study, using the partial least square method, prediction of the behavior of drugs with amine moiety upon chiral separation became possible from their three dimensional molecular structures. When a mixed mobile phase of 10 mM aqueous phosphate buffer (pH 7.0) - isopropanol (95:5) was employed, the best Quantitative CoMFA-Resolution Relationship, derived from the study, provided a cross-validated q2 = 0.933, a normal r2 = 0.995, while the best Quantitative CoMFA-Separation Factor Relationship, also derived from the study, yielded a cross-validated q2 = 0.939, a normal r2 = 0.991. When all of these results are considered, this QSRR-CoMFA analysis appears to be a very useful tool for the preliminary prediction on the chromatographic behaviors of drugs with an amine moiety inside chiral CBH columns.
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Affiliation(s)
- Sun Ok Choi
- Division of Biopharmaceutics, Department of Pharmacology, National Institute of Toxicological Research, Korea Food and Drug Administration, Seoul 122-704, Korea
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28
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Götmar G, Ozen C, Serpersu E, Guiochon G. Isothermal microcalorimetric study of the pH dependence of the interactions between a cellulase and a β-blocker. J Chromatogr A 2004. [DOI: 10.1016/j.chroma.2004.06.089] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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29
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Millot MC. Separation of drug enantiomers by liquid chromatography and capillary electrophoresis, using immobilized proteins as chiral selectors. J Chromatogr B Analyt Technol Biomed Life Sci 2003; 797:131-59. [PMID: 14630147 DOI: 10.1016/j.jchromb.2003.08.035] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Proteins display interesting chiral discrimination properties owing to multiple possibilities of intermolecular interactions with chiral compounds. This review deals with proteins which have been used as immobilized chiral selectors for the enantioseparation of drugs in liquid chromatography and capillary electrophoresis. The main procedures allowing the immobilization of proteins onto matrices, such as silica and zirconia particles, membranes and capillaries are first presented. Then the factors affecting the enantioseparation of drugs in liquid chromatography, using various protein-based chiral stationary phases (CSPs), are reviewed and discussed. Last, chiral separations already achieved using immobilized protein selectors in affinity capillary electrochromatography (ACEC) are presented and compared in terms of efficiency, stability and reproducibility.
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Affiliation(s)
- M C Millot
- Laboratoire de Recherche sur les Polymères, CNRS-Université Paris 12, UMR 7581, 2 à 8 rue Henri Dunant, Thiais 94320, France.
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30
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Ståhlberg J, Henriksson H, Divne C, Isaksson R, Pettersson G, Johansson G, Jones TA. Structural basis for enantiomer binding and separation of a common beta-blocker: crystal structure of cellobiohydrolase Cel7A with bound (S)-propranolol at 1.9 A resolution. J Mol Biol 2001; 305:79-93. [PMID: 11114249 DOI: 10.1006/jmbi.2000.4237] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Cellobiohydrolase Cel7A (previously called CBH 1), the major cellulase produced by the mould fungus Trichoderma reesei, has been successfully exploited as a chiral selector for separation of stereo-isomers of some important pharmaceutical compounds, e.g. adrenergic beta-blockers. Previous investigations, including experiments with catalytically deficient mutants of Cel7A, point unanimously to the active site as being responsible for discrimination of enantiomers. In this work the structural basis for enantioselectivity of basic drugs by Cel7A has been studied by X-ray crystallography. The catalytic domain of Cel7A was co-crystallised with the (S)-enantiomer of a common beta-blocker, propranolol, at pH 7, and the structure of the complex was determined and refined at 1. 9 A resolution. Indeed, (S)-propranolol binds at the active site, in glucosyl-binding subsites -1/+1. The catalytic residues Glu212 and Glu217 make tight salt links with the secondary amino group of (S)-propranolol. The oxygen atom attached to the chiral centre of (S)-propranolol forms hydrogen bonds to the nucleophile Glu212 O(epsilon1) and to Gln175 N(epsilon2), whereas the aromatic naphthyl moiety stacks with the indole ring of Trp376 in site +1. The bidentate charge interaction with the catalytic glutamate residues is apparently crucial, since no enantioselectivity has been obtained with the catalytically deficient mutants E212Q and E217Q. Activity inhibition experiments with wild-type Cel7A were performed in conditions close to those used for crystallisation. Competitive inhibition constants for (R)- and (S)-propranolol were determined at 220 microM and 44 microM, respectively, corresponding to binding free energies of 20 kJ/mol and 24 kJ/mol, respectively. The K(i) value for (R)-propranolol was 57-fold lower than the highest concentration, 12.5 mM, used in co-crystallisation experiments. Still several attempts to obtain a complex with the (R)-enantiomer have failed. By using cellobiose as a selective competing ligand, the retention of the enantiomers of propranolol on the chiral stationary phase (CSP) based on Cel7A mutant D214N were resolved into enantioselective and non- selective binding. The enantioselective binding was weaker for both enantiomers on D214N-CSP than on wild-type-CSP.
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Affiliation(s)
- J Ståhlberg
- Department of Molecular Biology, University of Uppsala, Uppsala, SE-751 24, Sweden
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31
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Götmar G, Fornstedt T, Andersson M, Guiochon G. Influence of the solute hydrophobicity on the enantioselective adsorption of beta-blockers on a cellulase protein used as the chiral selector. J Chromatogr A 2001; 905:3-17. [PMID: 11206798 DOI: 10.1016/s0021-9673(00)00971-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Adsorption isotherm data were acquired at different eluent pH values for the enantiomers of several beta-blockers on cellobiohydrolase I on silica gel. They fit well to the biLangmuir model, allowing the determination of the equilibrium constants and the monolayer capacities for chiral and nonselective adsorption. The adsorption of the S-enantiomers (eluted second) is exothermic at low pH, endothermic at high pH, and athermal in a narrow pH range depending on the beta-blocker. This transition pH range is lower for S-alprenolol than for the more hydrophobic S-propranolol, although their endothermic adsorption originates from hydrophobic interactions. This surprising observation is explained by the relative values of the isotherm coefficients. S-Alprenolol seems to have a more pronounced endothermic behavior than S-propranolol because the nonselective interactions of both compounds with the stationary phase are exothermic but their contribution to retention, relative to that of the endothermic chiral interactions, is less important for alprenolol. The order of increasing energy of the chiral interactions is the same as that of hydrophobicity, propranolol>alprenolol>metoprolol.
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Affiliation(s)
- G Götmar
- Department of Pharmacy, BMC, Uppsala, Sweden
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32
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Henriksson H, Muñoz IG, Isaksson R, Pettersson G, Johansson G. Cellobiohydrolase 58 (P.c. Cel 7D) is complementary to the homologous CBH I (T.r. Cel 7A) in enantioseparations. J Chromatogr A 2000; 898:63-74. [PMID: 11185624 DOI: 10.1016/s0021-9673(00)00807-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Cellobiohydrolase 58 (EC 3.2.1.91, P.c. Cel 7D) from Phanerochaete chrysosporium was immobilized on silica and the resulting material, CBH 58-silica, was then used as a chiral stationary phase (CSP) in liquid chromatographic separations of enantiomers. The enantioselectivities obtained on CBH 58-silica were compared with those on CBH I-silica (a phase based on a corresponding cellulase from Trichoderma reesei). CBH 58-silica displayed higher selectivity than CBH I-silica for the more hydrophilic compounds, such as atenolol and metoprolol, although great similarities in chiral separation of beta-adrenergic antagonists were found between the two phases. None of the acidic compounds tested could be resolved on the CBH 58 phase. Moreover, the solutes were retained more on the CBH 58 phase in general, indicating an improved application potential in bioanalysis. Addition of cellobiose or lactose, both of which are inhibitors of cellulases, to the mobile phase impaired the enantioselectivity, indicating an overlap of the enantioselective and catalytic sites. The chiral analytes also functioned as competitive inhibitors and their inhibition constants were determined.
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Affiliation(s)
- H Henriksson
- Department of Biochemistry, Uppsala University, Biomedical Centre, Sweden
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33
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Götmar G, Fornstedt T, Guiochon G. Retention mechanism of beta-blockers on an immobilized cellulase. Relative importance of the hydrophobic and ionic contributions to their enantioselective and nonselective interactions. Anal Chem 2000; 72:3908-15. [PMID: 10959981 DOI: 10.1021/ac9914824] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The adsorption isotherms of the enantiomers of three beta-blockers, metoprolol, alprenolol, and propranolol, were measured on cellobiohydrolase I (CBH I) immobilized on silicagel, in the concentration range between 0.25 microM and 1.7 mM, at pH = 5.0, 5.5, and 6.0. In agreement with previous results, these data are accounted for by a two-sites physical model and fit closely to a Bilangmuir equation. The saturation capacities and the binding constants were determined for each enantiomer on the chiral and the nonchiral sites. The chiral sites are shown to be strongly ionic, in contrast to the nonchiral ones, which are mainly hydrophobic. However, the chiral binding of (S)-propranolol is endothermic, with a high adsorption entropy, in contrast to the chiral interactions of (R)-propranolol and to the nonchiral interactions, which are all exothermic. This indicates that hydrophobic interactions also play a role in the chiral binding. The dependence of the adsorption parameters on the hydrophobicity of the solute is discussed and interpreted in terms of the retention mechanism. The results are compared with the structure of the protein, recently elucidated by X-ray crystallography.
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Affiliation(s)
- G Götmar
- Department of Pharmacy, BMC, Uppsala, Sweden
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34
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Abstract
The separation factor of two compounds in chromatography is the ratio of their equilibrium constants or retention factors. This parameter is universally employed to investigate their resolution and to optimize the experimental conditions of their analysis. In enantioseparations, the situation is more complex because there is a mixed retention mechanism. The retention factor is the sum of two contributions, one enantioselective, the other nonselective. Although both contribute to retention, the latter being identical for the two enantiomers and does not contribute to their separation. We show how these two contributions can be measured and how it becomes necessary to distinguish between the apparent, alpha(app), and the true, alpha(true), separation factors. The existence of nonselective sites is responsible for alpha(app) being less than alpha(true). Depending on the difference between these two factors, the more effective approach to improve a separation is either to increase the enantioselectivity or to reduce the nonselective interactions. Practical applications to separations of different beta-blockers on cellobiohydrolase are discussed. The apparent enantioselectivity of alprenolol is larger and increases faster with increasing pH than that of the more hydrophobic propranolol, in spite of the importance of hydrophobic interactions in the enantioselective mechanism. These two unexpected properties are discussed and explained.
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Affiliation(s)
- G Götmar
- Department of Pharmacy, Uppsala, Sweden
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35
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Hedeland M, Nygård M, Isaksson R, Pettersson C. Cellulases from the fungi Phanerochaete chrysosporium and Trichoderma reesei as chiral selectors in capillary electrophoresis: applications with displacer plugs and sample preconcentration. Electrophoresis 2000; 21:1587-96. [PMID: 10832892 DOI: 10.1002/(sici)1522-2683(20000501)21:8<1587::aid-elps1587>3.0.co;2-n] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The cellulases CBH 58 from the fungus Phanerochaete chrysosporium and CBH I from the fungus Trichoderma reesei were compared as chiral selectors in capillary electrophoresis (CE) applying the partial filling technique. Amines, e.g., norephedrine, two bambuterol analogs, as well as acids, e.g., di-p-toluoyl tartaric acid and dibenzoyl tartaric acid, which could not be enantioseparated in the liquid chromatographic use of the selectors, could be separated in the corresponding CE experiments. Due to the very high enantioselectivities, terbutaline, alprenolol and propranolol could be completely enantioresolved with selector plugs shorter than the sample plugs. The affinity of propranolol to CBH 58 was so high at pH 7.0 that neither of the enantiomers reached the detector; therefore, a plug of the displacing disaccharide cellobiose was injected after the sample to elute the propranolol enantiomers. The enantiomers could also be made to leave the capillary at opposite ends, thereby causing an infinite enantioresolution. A new preconcentration technique was introduced, which takes advantage of the very high affinity of propranolol to CBH 58 and the eluting ability of cellobiose. A 12.5 cm long plug of rac-propranolol could be preconcentrated and enantioseparated in a single procedure.
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Affiliation(s)
- M Hedeland
- Department of Pharmaceutical Chemistry, Biomedical Center, Uppsala University, Sweden
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36
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Hedeland M, Holmin S, Nygård M, Pettersson C. Chromatographic evaluation of structure selective and enantioselective retention of amines and acids on cellobiohydrolase I wild type and its mutant D214N. J Chromatogr A 1999; 864:1-16. [PMID: 10630866 DOI: 10.1016/s0021-9673(99)00968-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The mechanisms of structure selective and enantioselective retentions of amines and acids on two chiral stationary phases based on wild type cellobiohydrolase I (CBH I) and its mutant D214N have been investigated. All the amino alcohols tested had an enantioselective site that overlaps with the catalytically active site of CBH I, whereas the enantioselectivity of prilocaine was not affected by the mutation. The hydroxyl group of the amino alcohols did not seem to be an important contributor to the total binding strength whereas a bromo substituent in the aromatic ring promotes a high enantioselectivity (alpha=7.05). Interestingly, the chiral recognition site of the acid warfarin overlaps with the binding site of the amino alcohols. Di-p-toluoyltartaric acid and dibenzoyltartaric acid were strongly retained probably due to electrostatic attraction, but no enantioselectivity was observed. The difference in retention characteristics for the amino alcohols on the two stationary phases was strongly pH-dependent. A change in elution order of different amino alcohols occurred when changing the pH from 5.0 to 7.0. The difference between the two phases was lower at low pH. The retention times could also be affected by ionic strength and by use of cellobiose as a mobile phase additive but no indication of ion-pair retention of the amines was observed, when adding hexanesulphonate as counter ion to the mobile phase. The temperature dependence of the retention of the enantiomers of propranolol at pH 7.0 on the mutant D214N was similar to what was earlier observed on the wild type CBH I at lower pH.
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Affiliation(s)
- M Hedeland
- Department of Pharmaceutical Chemistry, Analytical Pharmaceutical Chemnistry, Uppsala University, Biomedical Centre, Sweden
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37
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Henriksson H, Pettersson G, Johansson G. Discrimination between enantioselective and non-selective binding sites on cellobiohydrolase-based stationary phases by site specific competing ligands. J Chromatogr A 1999; 857:107-15. [PMID: 10536829 DOI: 10.1016/s0021-9673(99)00776-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A systematic study was performed to investigate the influence of cellobiose or lactose on the enantioselective retention behaviour of some beta-blockers in liquid chromatography using Cellobiohydrolase (CHB) I from Trichoderma reesei or Cellobiohydrolase 58 from Phanerochaete chrysosporium immobilized on silica as stationary phases. The results revealed that the retention could be described by the function [equation; see text] where the observed capacity factor corresponds to the sum of an enantioselective mode being influenced by a site specific competing ligand (competitor) and a non-selective mode unaffected by the competitor. A non-constrained non-linear least-square regression gave in all cases virtually identical nondisplacable capacity factors (k'ns) for both enantiomers of the same drug. The experimental capacity factors (k'(x,C)) of the enantiomers all show a close fit to the adapted function. The Kd values calculated for the competitor were also virtually identical for each pair of enantiomers and were in accordance with Ki data determined for the competitors in classical enzyme kinetics experiments, demonstrating that one unique site; namely, the catalytic site, was responsible for the enantioselective binding. Similar results were obtained with the resolution of rac-alprenolol and rac-metoprolol on CBH I phase.
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Affiliation(s)
- H Henriksson
- Department of Biochemistry, Uppsala University, Biomedical Centre, Sweden
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38
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Fornstedt T, Götmar G, Andersson M, Guiochon G. Dependence on the Mobile-Phase pH of the Adsorption Behavior of Propranolol Enantiomers on a Cellulase Protein Used as the Chiral Selector. J Am Chem Soc 1999. [DOI: 10.1021/ja9831296] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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39
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Hedeland M, Henriksson H, Isaksson R, Pettersson G. Studies on the enantioselective retention mechanisms of cellobiohydrolase I (CBH I) by covalent modification of the intact and fragmented protein. Chirality 1998. [DOI: 10.1002/(sici)1520-636x(1998)10:8<760::aid-chir7>3.0.co;2-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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40
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Henriksson H, Ståhlberg J, Koivula A, Pettersson G, Divne C, Valtcheva L, Isaksson R. The catalytic amino-acid residues in the active site of cellobiohydrolase 1 are involved in chiral recognition. J Biotechnol 1997. [DOI: 10.1016/s0168-1656(97)00094-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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41
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Nilsson S, Schweitz L, Petersson M. Three approaches to enantiomer separation of beta-adrenergic antagonists by capillary electrochromatography. Electrophoresis 1997; 18:884-90. [PMID: 9221873 DOI: 10.1002/elps.1150180606] [Citation(s) in RCA: 109] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Three different capillary electrochromatographic methods for the enantiomer separation of beta-adrenergic antagonists (acebutolol, alprenolol, atenolol, metoprolol, pindolol, prenalterol, and propranolol) were applied using different cyclodextrins (beta-cyclodextrin, carboxymethyl-beta-cyclodextrin and dimethyl-beta-cyclodextrin) added to the electrolyte, a cross-linked protein-gel (cellobiohydrolase I) and a molecularly imprinted ((R)-enantiomer of propranolol) superporous polymer as chiral selectors. Through use of these different separation strategies, all the beta-adrenergic antagonists studied could be resolved into their enantiomers, although the three methods were carried out without extensive optimization. The protein and molecularly imprinted phases gave the highest selectivities whereas employing cyclodextrins resulted in the highest separation efficiency. Proteins and cyclodextrins are primarily natural products, albeit the cyclodextrins can be derivatized. In contrast, the molecularly imprinted chiral stationary phase can be highly customized when produced.
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Affiliation(s)
- S Nilsson
- Technical Analytical Chemistry, Center for Chemistry and Chemical Engineering, Lund University, Sweden.
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