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Gu Y, Bloomer BJ, Liu Z, Chen R, Clark DS, Hartwig JF. Directed Evolution of Artificial Metalloenzymes in Whole Cells. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202110519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Yang Gu
- Department of Chemistry University of California Berkeley CA 94720 USA
- Chemical Sciences Division Lawrence Berkeley National Laboratory 1 Cyclotron Road Berkeley CA 94720 USA
- Present address: CAS Key Laboratory of Quantitative Engineering Biology Shenzhen Institute of Synthetic Biology Shenzhen Institutes of Advanced Technology Chinese Academy of Sciences Shenzhen China
| | - Brandon J. Bloomer
- Department of Chemistry University of California Berkeley CA 94720 USA
- Chemical Sciences Division Lawrence Berkeley National Laboratory 1 Cyclotron Road Berkeley CA 94720 USA
| | - Zhennan Liu
- Department of Chemistry University of California Berkeley CA 94720 USA
- Chemical Sciences Division Lawrence Berkeley National Laboratory 1 Cyclotron Road Berkeley CA 94720 USA
| | - Reichi Chen
- Department of Chemistry University of California Berkeley CA 94720 USA
- Chemical Sciences Division Lawrence Berkeley National Laboratory 1 Cyclotron Road Berkeley CA 94720 USA
| | - Douglas S. Clark
- Department of Chemical and Biomolecular Engineering University of California Berkeley CA 94720 USA
- Molecular Biophysics and Integrated Bioimaging Division Lawrence Berkeley National Laboratory 1 Cyclotron Road Berkeley CA 94720 USA
| | - John F. Hartwig
- Department of Chemistry University of California Berkeley CA 94720 USA
- Chemical Sciences Division Lawrence Berkeley National Laboratory 1 Cyclotron Road Berkeley CA 94720 USA
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Gu Y, Bloomer BJ, Liu Z, Chen R, Clark DS, Hartwig JF. Directed Evolution of Artificial Metalloenzymes in Whole Cells. Angew Chem Int Ed Engl 2022; 61:e202110519. [PMID: 34766418 PMCID: PMC9707807 DOI: 10.1002/anie.202110519] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2021] [Revised: 10/15/2021] [Indexed: 01/28/2023]
Abstract
Artificial metalloenzymes (ArMs), created by introducing synthetic cofactors into protein scaffolds, are an emerging class of catalyst for non-natural reactions. Although many classes of ArMs are known, in vitro reconstitution of cofactors and proteins has been a limiting step in the high-throughput screening and directed evolution of ArMs because purification of individual host proteins is time-consuming. We describe the application of a platform to combine mutants of the P450 enzyme CYP119 and the cofactor Ir(Me)MPIX in vivo, by coexpression of the CYP119 mutants with the heme transporter encoded by the hug operon, to the directed evolution of ArMs containing Ir(Me)MPIX in whole cells. We applied this platform to the development an ArMs catalyzing the insertion of the acyclic carbene from α-diazopropanoate esters (Me-EDA) into the N-H bonds of N-alkyl anilines, a combination of carbene and amine classes for which mutant enzymes of natural hemoproteins previously reacted with low enantioselectivity. The mutants of the artificial metalloenzyme Ir(Me)CYP119 identified by an evolution campaign involving more than 4000 mutants are shown to catalyze the reaction of Me-EDA with N-methyl anilines to form chiral chiral amino esters with high TON and good enantioselectivity, thereby demonstrating that the directed evolution of ArMs can rival that of natural enzymes in vivo.
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Affiliation(s)
- Yang Gu
- Department of Chemistry, University of California, Berkeley, CA, 94720, USA
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, USA
- Present address: CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Brandon J Bloomer
- Department of Chemistry, University of California, Berkeley, CA, 94720, USA
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, USA
| | - Zhennan Liu
- Department of Chemistry, University of California, Berkeley, CA, 94720, USA
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, USA
| | - Reichi Chen
- Department of Chemistry, University of California, Berkeley, CA, 94720, USA
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, USA
| | - Douglas S Clark
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA, 94720, USA
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, USA
| | - John F Hartwig
- Department of Chemistry, University of California, Berkeley, CA, 94720, USA
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, USA
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Zhao H. What do we learn from enzyme behaviors in organic solvents? - Structural functionalization of ionic liquids for enzyme activation and stabilization. Biotechnol Adv 2020; 45:107638. [PMID: 33002582 DOI: 10.1016/j.biotechadv.2020.107638] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 09/05/2020] [Accepted: 09/25/2020] [Indexed: 12/16/2022]
Abstract
Enzyme activity in nonaqueous media (e.g. conventional organic solvents) is typically lower than in water by several orders of magnitude. There is a rising interest of developing new nonaqueous solvent systems that are more "water-like" and more biocompatible. Therefore, we need to learn from the current state of nonaqueous biocatalysis to overcome its bottleneck and provide guidance for new solvent design. This review firstly focuses on the discussion of how organic solvent properties (such as polarity and hydrophobicity) influence the enzyme activity and stability, and how these properties impact the enzyme's conformation and dynamics. While hydrophobic organic solvents usually lead to the maintenance of enzyme activity, solvents carrying functional groups like hydroxys and ethers (including crown ethers and cyclodextrins) can lead to enzyme activation. Ionic liquids (ILs) are designable solvents that can conveniently incorporate these functional groups. Therefore, we systematically survey these ether- and/or hydroxy-functionalized ILs, and find most of them are highly compatible with enzymes leading to high activity and stability. In particular, ILs carrying both ether and tert-alcohol groups are among the most enzyme-activating solvents. Future direction is to learn from enzyme behaviors in both water and nonaqueous media to design biocompatible "water-like" solvents.
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Affiliation(s)
- Hua Zhao
- Department of Chemistry and Biochemistry, University of Northern Colorado, Greeley, CO 80639, United States.
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Huang J, Xu Y, Zhang Y, Sun A, Hu Y. Utilization of one novel deep-sea microbial protease sin3406-1 in the preparation of ethyl (S)-3-hydroxybutyrate through kinetic resolution. World J Microbiol Biotechnol 2018; 34:124. [PMID: 30083971 DOI: 10.1007/s11274-018-2513-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 08/01/2018] [Indexed: 10/28/2022]
Abstract
One novel protease sin3406-1 was identified from Streptomyces niveus SCSIO 3406, which was isolated from the deep sea of the South China Sea, and heterologously expressed in E. coli BL21(DE3). Protease sin3406-1 was further used as a green biocatalyst in the kinetic resolution of racemic ethyl-3-hydroxybutyrate. After careful process optimization, chiral product ethyl (S)-3-hydroxybutyrate was generated with an enantiomeric excess of over 99% and a conversion rate of up to 50% through direct hydrolysis of inexpensive racemic ethyl-3-hydroxybutyrate catalyzed by sin3406-1. Interestingly, protease sin3406-1 exhibited the same enantio-preference as that of esterase PHE21 during the asymmetric hydrolysis of the ester bonds of racemic ethyl-3-hydroxybutyrate. Through mutation studies and molecular docking, we also demonstrated that the four residues close to the catalytic center, S85, A86, Q87 and Y254, played key roles in both the hydrolytic activity and the enantioselectivity of protease sin3406-1, possibly through forming hydrogen bonds between the enzyme and the substrates. Deep-sea microbial proteases represented by sin3406-1 are new contributions to the biocatalyst library for the preparation of valuable chiral drug intermediates and chemicals through enzymatic kinetic resolution.
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Affiliation(s)
- Jinlong Huang
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, People's Republic of China.,Guangdong Key Laboratory of Marine Materia Medica, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, People's Republic of China.,College of Life Science, Guangxi Normal University, Guilin, 541004, People's Republic of China
| | - Yongkai Xu
- Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jinan, 250014, Shandong, People's Republic of China
| | - Yun Zhang
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, People's Republic of China.,Guangdong Key Laboratory of Marine Materia Medica, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, People's Republic of China
| | - Aijun Sun
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, People's Republic of China.,Guangdong Key Laboratory of Marine Materia Medica, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, People's Republic of China
| | - Yunfeng Hu
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, People's Republic of China. .,Guangdong Key Laboratory of Marine Materia Medica, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, People's Republic of China. .,South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center, Guangzhou, People's Republic of China.
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Dorau R, Görbe T, Svedendahl Humble M. Improved Enantioselectivity of Subtilisin Carlsberg towards Secondary Alcohols by Protein Engineering. Chembiochem 2018; 19:338-346. [PMID: 29105250 DOI: 10.1002/cbic.201700408] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Indexed: 11/07/2022]
Abstract
Generally, the catalytic activity of subtilisin Carlsberg (SC) for transacylation reactions with secondary alcohols in organic solvent is low. Enzyme immobilization and protein engineering was performed to improve the enantioselectivity of SC towards secondary alcohols. Possible amino-acid residues for mutagenesis were found by combining available literature data with molecular modeling. SC variants were created by site-directed mutagenesis and were evaluated for a model transacylation reaction containing 1-phenylethanol in THF. Variants showing high E values (>100) were found. However, the conversions were still low. A second mutation was made, and both the E values and conversions were increased. Relative to that shown by the wild type, the most successful variant, G165L/M221F, showed increased conversion (up to 36 %), enantioselectivity (E values up to 400), substrate scope, and stability in THF.
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Affiliation(s)
- Robin Dorau
- Division of Industrial Biotechnology, School of Biotechnology, KTH Royal Institute of Technology, AlbaNova University Center, 106 91, Stockholm, Sweden
- Division of Microbiology and Production, National Food Institute, Technical University of Denmark, Kemitorvet, Bygning 201, 2800, Kgs. Lyngby, Denmark
| | - Tamás Görbe
- Department of Organic Chemistry, Stockholm University, Arrhenius Laboratory, 106 91, Stockholm, Sweden
| | - Maria Svedendahl Humble
- Division of Industrial Biotechnology, School of Biotechnology, KTH Royal Institute of Technology, AlbaNova University Center, 106 91, Stockholm, Sweden
- Pharem Biotech AB, Biovation Park, Forskargatan 20 J, 151 36, Stockholm, Sweden
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Liang YR, Wu Q, Lin XF. Effect of Additives on the Selectivity and Reactivity of Enzymes. CHEM REC 2016; 17:90-121. [PMID: 27490244 DOI: 10.1002/tcr.201600016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Indexed: 01/05/2023]
Abstract
Enzymes have been widely used as efficient, eco-friendly, and biodegradable catalysts in organic chemistry due to their mild reaction conditions and high selectivity and efficiency. In recent years, the catalytic promiscuity of many enzymes in unnatural reactions has been revealed and studied by chemists and biochemists, which has expanded the application potential of enzymes. To enhance the selectivity and activity of enzymes in their natural or promiscuous reactions, many methods have been recommended, such as protein engineering, process engineering, and media engineering. Among them, the additive approach is very attractive because of its simplicity to use and high efficiency. In this paper, we will review the recent developments about the applications of additives to improve the catalytic performances of enzymes in their natural and promiscuous reactions. These additives include water, organic bases, water mimics, cosolvents, crown ethers, salts, surfactants, and some particular molecular additives.
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Affiliation(s)
- Yi-Ru Liang
- Department of Chemistry, Zhejiang University, Hangzhou, 310027, P. R. China
| | - Qi Wu
- Department of Chemistry, Zhejiang University, Hangzhou, 310027, P. R. China
| | - Xian-Fu Lin
- Department of Chemistry, Zhejiang University, Hangzhou, 310027, P. R. China
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Gupta MN, Mukherjee J, Malhotra D. Use of high activity enzyme preparations in neat organic solvents for organic synthesis. ACTA ACUST UNITED AC 2013. [DOI: 10.7243/2053-7670-1-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Sergeev ME, Voyushina TL, Sergeeva OA, Belozerskaya GG. Efficient enzyme-catalyzed synthesis of peptide secondary amides for use as serine proteinase inhibitors. ACTA ACUST UNITED AC 2012. [DOI: 10.1016/j.molcatb.2012.04.019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Petkova GA, Král V. Ketoreductase activity for reduction of substituted-β-tetralones utilizing aqueous-organic systems and β-cyclodextrin derivatives. BIOCATAL BIOTRANSFOR 2012. [DOI: 10.3109/10242422.2012.662960] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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O'Reilly NJ, Magner E. The effect of solvent on the catalytic properties of microperoxidase-11. Phys Chem Chem Phys 2011; 13:5304-13. [DOI: 10.1039/c0cp02321c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Castillo B, Delgado Y, Barletta G, Griebenow K. Enantioselective Transesterification Catalysis by Nanosized Serine Protease Subtilisin Carlsberg Particles in Tetrahydrofuran. Tetrahedron 2010; 66:2175-2180. [PMID: 20661313 DOI: 10.1016/j.tet.2010.01.053] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Enzyme catalysis in organic solvents is a powerful tool for stereo-selective synthesis but the enantioselectivity is still hard to predict. To overcome this obstacle, we employed a nanoparticulate formulation of subtilisin Carlsberg (SC) and designed a series of 14 structurally related racemic alcohols. They were employed in the model transesterification reaction with vinyl butyrate and the enantioselectivities were determined. In general, short alcohol side chains led to low enantioselectivties, while larger and bulky side chains caused better discrimination of the enantiomers by the enzyme. With several bulky substrates high enantioselectivities with E>100 were obtained. Computational modeling highlighted that key to high enantioselectivity is the discrimination of the R and S substrates by the sole hydrophobic binding pocket based on their size and bulkiness. While bulky S enantiomer side chains could be accommodated within the binding pocket, bulky R enantiomer side chains could not. However, when also the S enantiomer side chain becomes too large and does not fit into the binding pocket anymore, enantioselectivity accordingly drops.
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Affiliation(s)
- Betzaida Castillo
- Department of Chemistry, University of Puerto Rico, Río Piedras Campus, P.O. Box 23346, San Juan, Puerto Rico 00931-3346
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Cruz A, Ramirez E, Santana A, Barletta G, López GE. Molecular dynamic study of subtilisin Carlsberg in aqueous and nonaqueous solvents. MOLECULAR SIMULATION 2009. [DOI: 10.1080/08927020802415670] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Pérez-Victoria I, Morales JC. One- and two-step enzymatic synthesis of polymerizable vinyladipoyl mono- and diesters of non-reducing trisaccharides. ACTA ACUST UNITED AC 2007. [DOI: 10.1016/j.molcatb.2007.05.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Fasoli E, Castillo B, Santos A, Silva E, Ferrer A, Rosario E, Griebenow K, Secundo F, Barletta GL. Activation of subtilisin Carlsberg in organic solvents by methyl-β-cyclodextrin: Lyoprotection versus substrate and product-complex effect. ACTA ACUST UNITED AC 2006. [DOI: 10.1016/j.molcatb.2006.05.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Castillo B, Méndez J, Al-Azzam W, Barletta G, Griebenow K. On the relationship between the activity and structure of PEG-alpha-chymotrypsin conjugates in organic solvents. Biotechnol Bioeng 2006; 94:565-74. [PMID: 16496401 DOI: 10.1002/bit.20863] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Enzymes are attractive catalysts for the production of optically active compounds in organic solvents. However, their often low catalytic activity in such applications hampers their practical use. To overcome this, we investigated the effectiveness of the covalent modification of alpha-chymotrypsin with methoxy poly(ethylene glycol) (PEG) with a Mw of 5,000 to enhance its activity. The model transesterification reaction between sec-phenethyl alcohol and vinyl butyrate in various neat dry organic solvents and at a controlled water activity of 0.008 in two solvents was employed to measure the effect of PEGylation on activity and enantioselectivity. Synthesis conditions were varied to obtain various conjugates with average molar ratios of PEG-to-chymotrypsin ranging from ca. 1 to 7. While the enantioselectivity increased only modestly from ca. 4.4 to 6.1 when averaging results in all solvents, PEG was very efficient in increasing the activity of alpha-chymotrypsin up to more than 400-fold compared to that of the powder lyophilized from buffer alone. The activity increase was more pronounced in apolar than in polar organic solvents and also depended on the amount of PEG bound to the enzyme. For example, the activity of the modified enzyme towards the most reactive "S" enantiomer in octane increased 440-fold but increasing the molar ratio of PEG-to-enzyme from 1.1 to 7.1 resulted in a more than twofold decrease in enzyme activity. Controlling the water activity did not prevent the drop in activity. To investigate the possible origin of the activity changes, Fourier transform infrared (FTIR) spectroscopy experiments were conducted. It was found that PEGylation reduced lyophilization-induced structural perturbations, but exposure to the organic solvents caused structural perturbations. These perturbations were more pronounced in polar than in apolar solvents. The pronounced activity drop in polar solvents at increasing PEG-modification levels correlated with an increasing level of solvent-induced structural perturbations. This correlation was less pronounced in apolar solvents where both, activity drop and structural perturbations, were less pronounced at increasing PEGylation levels. In summary, PEG-modified alpha-chymotrypsin might be an interesting system to catalyze reactions, particularly in apolar organic solvents.
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Affiliation(s)
- Betzaida Castillo
- Department of Chemistry, University of Puerto Rico, Río Piedras Campus, P.O. Box 23346, San Juan, Puerto Rico
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Pérez-Victoria I, Morales JC. Complementary regioselective esterification of non-reducing oligosaccharides catalyzed by different hydrolases. Tetrahedron 2006. [DOI: 10.1016/j.tet.2005.10.046] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Affiliation(s)
- J Jegan Roy
- Biochemical Processing Section, Regional Research Laboratory (CSIR), Trivandrum 695 019, India
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Han MS, Jung SO, Kim MJ, Kim DH. Fluorometric Assay Protocol for Protease-Catalyzed Transesterification Reactions in Organic Solvents. J Org Chem 2004; 69:2853-5. [PMID: 15074938 DOI: 10.1021/jo040104i] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A flourometric assay protocol for a subtilisin-catalyzed transesterification reaction in n-hexane has been developed. The method makes use of a Michael acceptor that forms a fluorescent adduct with thiophenol, one of the products generated in the transesterification reaction. The method may be employed for screening a biocatalyst useful for transesterification reactions in organic solvents and for optimizing the transesterification reaction conditions.
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Affiliation(s)
- Min Su Han
- Center for Integrated Molecular Systems, and National Research Laboratory of Chirotechnology, Department of Chemistry, Pohang University of Science and Technology, San 31 Hyojadong, Pohang 790-784, Korea
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Morgan JA, Clark DS. Salt-activation of nonhydrolase enzymes for use in organic solvents. Biotechnol Bioeng 2004; 85:456-9. [PMID: 14755564 DOI: 10.1002/bit.10895] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Enzymatic reactions are important for the synthesis of chiral molecules. One factor limiting synthetic applications of enzymes is the poor aqueous solubility of numerous substrates. To overcome this limitation, enzymes can be used directly in organic solvents; however, in nonaqueous media enzymes usually exhibit only a fraction of their aqueous-level activity. Salt-activation, a technique previously demonstrated to substantially increase the transesterification activity of hydrolytic enzymes in organic solvents, was applied to horse liver alcohol dehydrogenase, soybean peroxidase, galactose oxidase, and xanthine oxidase, which are oxidoreductase and oxygenase enzymes. Assays of the lyophilized enzyme preparations demonstrated that the presence of salt protected enzymes from irreversible inactivation. In organic solvents, there were significant increases in activity for the salt-activated enzymes compared to nonsalt-activated controls for every enzyme tested. The increased enzymatic activity in organic solvents was shown to result from a combination of protection against inactivation during the freeze-drying process and other as-yet undetermined factors.
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Affiliation(s)
- John A Morgan
- University of California, Berkeley, 201 Gilman Hall, Berkeley, California 94720, USA
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