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Siew YY, Zhang W. Downstream processing of recombinant human insulin and its analogues production from E. coli inclusion bodies. BIORESOUR BIOPROCESS 2021; 8:65. [PMID: 34336550 PMCID: PMC8313369 DOI: 10.1186/s40643-021-00419-w] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 07/20/2021] [Indexed: 11/10/2022] Open
Abstract
The Global Diabetes Compact was launched by the World Health Organization in April 2021 with one of its important goals to increase the accessibility and affordability of life-saving medicine-insulin. The rising prevalence of diabetes worldwide is bound to escalate the demand for recombinant insulin therapeutics, and currently, the majority of recombinant insulin therapeutics are produced from E. coli inclusion bodies. Here, a comprehensive review of downstream processing of recombinant human insulin/analogue production from E. coli inclusion bodies is presented. All the critical aspects of downstream processing, starting from proinsulin recovery from inclusion bodies, inclusion body washing, inclusion body solubilization and oxidative sulfitolysis, cyanogen bromide cleavage, buffer exchange, purification by chromatography, pH precipitation and zinc crystallization methods, proinsulin refolding, enzymatic cleavage, and formulation, are explained in this review. Pertinent examples are summarized and the practical aspects of integrating every procedure into a multimodal purification scheme are critically discussed. In the face of increasing global demand for insulin product, there is a pressing need to develop a more efficient and economical production process. The information presented would be insightful to all the manufacturers and stakeholders for the production of human insulins, insulin analogues or biosimilars, as they strive to make further progresses in therapeutic recombinant insulin development and production.
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Affiliation(s)
- Yin Yin Siew
- Downstream Processing Group, Bioprocessing Technology Institute, Agency for Science, Technology and Research, Singapore, Singapore
| | - Wei Zhang
- Downstream Processing Group, Bioprocessing Technology Institute, Agency for Science, Technology and Research, Singapore, Singapore
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2
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Refolding of denatured/reduced lysozyme by aromatic thiols in the absence of small molecule disulfide. RESEARCH ON CHEMICAL INTERMEDIATES 2014. [DOI: 10.1007/s11164-014-1706-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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3
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Abstract
Recombinant production has become an invaluable tool for supplying research and therapy with proteins of interest. The target proteins are not in every case soluble and/or correctly folded. That is why different production parameters such as host, cultivation conditions and co-expression of chaperones and foldases are applied in order to yield functional recombinant protein. There has been a constant increase and success in the use of folding promoting agents in recombinant protein production. Recent cases are reviewed and discussed in this chapter. Any impact of such strategies cannot be predicted and has to be analyzed and optimized for the corresponding target protein. The in vivo effects of the agents are at least partially comparable to their in vitro mode of action and have been studied by means of modern systems approaches and even in combination with folding/activity screening assays. Resulting data can be used directly for experimental planning or can be fed into knowledge-based modelling. An overview of such technologies is included in the chapter in order to facilitate a decision about the potential in vivo use of folding promoting agents.
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Affiliation(s)
- Beatrix Fahnert
- Cardiff School of Biosciences, Cardiff University, Wales, UK.
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4
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Patel AS, Lees WJ. Oxidative folding of lysozyme with aromatic dithiols, and aliphatic and aromatic monothiols. Bioorg Med Chem 2011; 20:1020-8. [PMID: 22197395 DOI: 10.1016/j.bmc.2011.11.049] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Revised: 11/16/2011] [Accepted: 11/19/2011] [Indexed: 11/28/2022]
Abstract
In vitro protein folding of disulfide containing proteins is aided by the addition of a redox buffer, which is composed of a small molecule disulfide and/or a small molecule thiol. In this study, we examined redox buffers containing asymmetric dithiols 1-5, which possess an aromatic and aliphatic thiol, and symmetric dithiols 6 and 7, which possess two aromatic thiols, for their ability to fold reduced lysozyme at pH 7.0 and 8.0. Most in vivo protein folding catalysts are dithiols. When compared to glutathione and glutathione disulfide, the standard redox buffer, dithiols 1-5 improved the protein folding rates but not the yields. However, dithiols 6 and 7, and the corresponding monothiol 8 increased the folding rates 8-17 times and improved the yields 15-42% at 1mg/mL lysozyme. Moreover, aromatic dithiol 6 increased the in vitro folding yield as compared to the corresponding aromatic monothiol 8. Therefore, aromatic dithiols should be useful for protein folding, especially at high protein concentrations.
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Affiliation(s)
- Amar S Patel
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th St., Miami, FL 33199, USA
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5
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Beld J, Woycechowsky KJ, Hilvert D. Small-molecule diselenides catalyze oxidative protein folding in vivo. ACS Chem Biol 2010; 5:177-82. [PMID: 20052969 DOI: 10.1021/cb9002688] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Prokaryotic cells normally rely on periplasmic oxidoreductases to promote oxidative protein folding. Here we show that simple diselenides can also facilitate the conversion of dithiols to disulfides in vivo, functionally replacing one such oxidoreductase, DsbA, in the oxidative folding of diverse proteins. Structurally analogous disulfides provide no detectable effect when used at concentrations that gave optimal activity with diselenides, and even at 100- to 1000-fold higher levels they show only partial activity. The low concentrations of diselenides needed to fully negate typical DsbA knockout phenotypes suggest catalysis in vivo, a property that sets these additives apart from other small molecules used in chemical biology. Supplementing growth media with cell-permeable organocatalysts provides a potentially general and operationally simple means of fine-tuning the cellular redox environment.
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Affiliation(s)
- Joris Beld
- Laboratory of Organic Chemistry, ETH Zürich, Hönggerberg HCI F339, CH-8093 Zürich, Switzerland
| | - Kenneth J. Woycechowsky
- Laboratory of Organic Chemistry, ETH Zürich, Hönggerberg HCI F339, CH-8093 Zürich, Switzerland
| | - Donald Hilvert
- Laboratory of Organic Chemistry, ETH Zürich, Hönggerberg HCI F339, CH-8093 Zürich, Switzerland
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Kouwen TRHM, van Dijl JM. Applications of thiol-disulfide oxidoreductases for optimized in vivo production of functionally active proteins in Bacillus. Appl Microbiol Biotechnol 2009; 85:45-52. [PMID: 19727703 PMCID: PMC2765640 DOI: 10.1007/s00253-009-2212-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2009] [Revised: 08/17/2009] [Accepted: 08/18/2009] [Indexed: 02/01/2023]
Abstract
Bacillus subtilis is a well-established cellular factory for proteins and fine chemicals. In particular, the direct secretion of proteinaceous products into the growth medium greatly facilitates their downstream processing, which is an important advantage of B. subtilis over other biotechnological production hosts, such as Escherichia coli. The application spectrum of B. subtilis is, however, often confined to proteins from Bacillus or closely related species. One of the major reasons for this (current) limitation is the inefficient formation of disulfide bonds, which are found in many, especially eukaryotic, proteins. Future exploitation of B. subtilis to fulfill the ever-growing demand for pharmaceutical and other high-value proteins will therefore depend on overcoming this particular hurdle. Recently, promising advances in this area have been achieved, which focus attention on the need to modulate the cellular levels and activity of thiol-disulfide oxidoreductases (TDORs). These TDORs are enzymes that control the cleavage or formation of disulfide bonds. This review will discuss readily applicable approaches for TDOR modulation and aims to provide leads for further improvement of the Bacillus cell factory for production of disulfide bond-containing proteins.
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Affiliation(s)
- Thijs R H M Kouwen
- Department of Medical Microbiology, University Medical Microbiology, University Medical Center Groningen, Groningen, The Netherlands
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Gusarova VD, Gusarov DA, Mironov AF, Bairamashvili DI, Miroshnikov AI. [Optimization of the industrial production of the recombinant precursor of human insulin]. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2009; 35:510-8. [PMID: 19928053 DOI: 10.1134/s1068162009040074] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Conditions were found at the analytical level for the solubilization of a recombinant insulin precursor from inclusion bodies in different buffer systems at a wide pH range in the presence of different reducing (dithiothreitol, dithioerythritol) and chaotropic agents (urea, guanidine hydrochloride) and the subsequent renaturation with the use of redox pairs (cysteine-cystine, oxidized glutathione-reduced glutathione, and others). The scaling of the method for the production of the active substance of genetically engineered human insulin has been performed.
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Madar DJ, Patel AS, Lees WJ. Comparison of the oxidative folding of lysozyme at a high protein concentration using aromatic thiols versus glutathione. J Biotechnol 2009; 142:214-9. [PMID: 19477205 DOI: 10.1016/j.jbiotec.2009.05.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2008] [Revised: 05/11/2009] [Accepted: 05/19/2009] [Indexed: 10/20/2022]
Abstract
The production of proteins using recombinant DNA technology often requires the use of in vitro protein folding. In order to facilitate in vitro protein folding, a redox buffer is added to the protein folding mixture. The redox buffer is composed of a small molecule disulfide and/or a small molecule thiol. Recently, redox buffers containing aromatic thiols have been shown to be an improvement over traditional redox buffers such as glutathione. For in vitro protein folding to be relevant to protein production on a larger scale, high protein concentrations are required to avoid large volumes of folding buffer. Therefore, we investigated the in vitro folding of lysozyme at 1 mg/mL instead of the traditional 0.1 mg/mL. Aromatic thiols and aromatic disulfides were compared directly with glutathione and glutathione disulfide, the most commonly used redox buffer. Folding experiments at pH 7 using aromatic thiols increased the yield by 20-40% and the folding rate constants by as much as 11 times relative to glutathione. At pH 8, improvements in yields of up to 25% and up to a 7-fold increase in folding rate constants were demonstrated. The effect of aromatic disulfide concentration was also investigated.
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Affiliation(s)
- David J Madar
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
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Rudolph R, Lange C. Strategies for the Oxidative in vitro Refolding of Disulfide-bridge-containing Proteins. OXIDATIVE FOLDING OF PEPTIDES AND PROTEINS 2008. [DOI: 10.1039/9781847559265-00192] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Rainer Rudolph
- Institut für Biochemie and Biotechnologie Martin-Luther-Universität Halle-Wittenberg Kurt-Mothes-Str. 3 06120 Halle (Saale) Germany
| | - Christian Lange
- Institut für Biochemie and Biotechnologie Martin-Luther-Universität Halle-Wittenberg Kurt-Mothes-Str. 3 06120 Halle (Saale) Germany
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10
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Lees WJ. Small-molecule catalysts of oxidative protein folding. Curr Opin Chem Biol 2008; 12:740-5. [DOI: 10.1016/j.cbpa.2008.08.032] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2008] [Revised: 08/10/2008] [Accepted: 08/26/2008] [Indexed: 11/28/2022]
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11
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Kruusma J, Rhodes A, Bhatia R, Williams JAG, Benham AM, Kataky R. The Effect of a Hydrogen Bonding Environment (Dimethyl Sulfoxide) on the Ionisation and Redox Properties of the Thiol Group in Cysteine and a Protein Disulfide Isomerase Mimic (Vectrase). J SOLUTION CHEM 2007. [DOI: 10.1007/s10953-007-9123-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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12
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Kruusma J, Benham AM, Williams JAG, Kataky R. An introduction to thiol redox proteins in the endoplasmic reticulum and a review of current electrochemical methods of detection of thiols. Analyst 2006; 131:459-73. [PMID: 16568160 DOI: 10.1039/b515874e] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
This aim of this paper is to expound the complexity of thiol redox systems in the endoplasmic reticulum of eukaryotic cells to the electroanalytical community. A summary of the state of the art in electrochemical methods for detection of thiols gives an insight into the challenges that need to be addressed to bridge the disparity between current analytical techniques and applications in a 'real' biological scenario.
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Affiliation(s)
- Jaanus Kruusma
- Chemistry Department and Centre for Bioactive Chemistry, University of Durham, South Road, Durham, UKDH1 4HT
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13
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Gough JD, Lees WJ. Effects of redox buffer properties on the folding of a disulfide-containing protein: dependence upon pH, thiol pKa, and thiol concentration. J Biotechnol 2005; 115:279-90. [PMID: 15639090 DOI: 10.1016/j.jbiotec.2004.09.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2004] [Revised: 09/20/2004] [Accepted: 09/27/2004] [Indexed: 10/26/2022]
Abstract
Aliphatic thiols are effective as redox buffers for folding non-native disulfide-containing proteins into their native state at high pH values (8.0-8.5) but not at neutral pH values (6-7.5). In developing more efficient and flexible redox buffers, a series of aromatic thiols was analyzed for its ability to fold scrambled ribonuclease A (sRNase A). At equivalent pH values, the aromatic thiols folded sRNase A 10-23 times faster at pH 6.0, 7-12 times faster at pH 7.0, and 5-8 times faster at pH 7.7 than the standard aliphatic thiol glutathione. Similar correlations between thiol pK(a) values and folding rates at each pH value suggest that the apparent folding rate constants (k(app)) are a function of the redox buffer properties (pH, thiol pK(a) and [RSH]). Fitting the observed data to a three-variable model (logk(app)=-4.216(+/-0.030)+0.5816(+/-0.0036)pH-0.233(+/-0.004)pK(a)+log(1-e(-0.98(+/-0.02)[RSH]))) gave good statistics: r2=0.915, s=0.10.
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Affiliation(s)
- Jonathan D Gough
- Department of Chemistry, Syracuse University, Syracuse, NY 13244, USA
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Gough JD, Lees WJ. Increased catalytic activity of protein disulfide isomerase using aromatic thiol based redox buffers. Bioorg Med Chem Lett 2005; 15:777-81. [PMID: 15664856 DOI: 10.1016/j.bmcl.2004.11.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2004] [Revised: 10/29/2004] [Accepted: 11/02/2004] [Indexed: 11/16/2022]
Abstract
PDI is an enzyme that acts as a chaperone, shufflase, and oxidase during the folding of disulfide-containing proteins. The ability of aromatic thiols to increase the activity of PDI-catalyzed protein folding over that of the standard thiol glutathione (GSH) was measured. 4-Mercaptobenzoic acid (ArSH) increased the activity of PDI by a factor of three.
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Affiliation(s)
- Jonathan D Gough
- Department of Chemistry, Syracuse University, Syracuse, NY 13244, USA
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Vallejo LF, Rinas U. Strategies for the recovery of active proteins through refolding of bacterial inclusion body proteins. Microb Cell Fact 2004; 3:11. [PMID: 15345063 PMCID: PMC517725 DOI: 10.1186/1475-2859-3-11] [Citation(s) in RCA: 240] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2004] [Accepted: 09/02/2004] [Indexed: 11/21/2022] Open
Abstract
Recent advances in generating active proteins through refolding of bacterial inclusion body proteins are summarized in conjunction with a short overview on inclusion body isolation and solubilization procedures. In particular, the pros and cons of well-established robust refolding techniques such as direct dilution as well as less common ones such as diafiltration or chromatographic processes including size exclusion chromatography, matrix- or affinity-based techniques and hydrophobic interaction chromatography are discussed. Moreover, the effect of physical variables (temperature and pressure) as well as the presence of buffer additives on the refolding process is elucidated. In particular, the impact of protein stabilizing or destabilizing low- and high-molecular weight additives as well as micellar and liposomal systems on protein refolding is illustrated. Also, techniques mimicking the principles encountered during in vivo folding such as processes based on natural and artificial chaperones and propeptide-assisted protein refolding are presented. Moreover, the special requirements for the generation of disulfide bonded proteins and the specific problems and solutions, which arise during process integration are discussed. Finally, the different strategies are examined regarding their applicability for large-scale production processes or high-throughput screening procedures.
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Affiliation(s)
- Luis Felipe Vallejo
- Biochemical Engineering Division, GBF German Research Center for Biotechnology, Mascheroder Weg 1, 38124 Braunschweig, Germany
| | - Ursula Rinas
- Biochemical Engineering Division, GBF German Research Center for Biotechnology, Mascheroder Weg 1, 38124 Braunschweig, Germany
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Narayan M, Welker E, Wanjalla C, Xu G, Scheraga HA. Shifting the competition between the intramolecular Reshuffling reaction and the direct oxidation reaction during the oxidative folding of kinetically trapped disulfide-insecure intermediates. Biochemistry 2003; 42:10783-9. [PMID: 12962503 DOI: 10.1021/bi030141o] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The oxidative folding pathway(s) of single-domain proteins can be characterized by the existence, stability, and structural nature of the intermediates that populate the regeneration pathway. Structured intermediates can be disulfide-secure in that they are able to protect their existing (native) disulfide bonds from SH/SS reshuffling and reduction reactions, and thereby form the native protein directly, i.e., by oxidation of their exposed (or locally exposable) thiols. Alternatively, they can be disulfide-insecure, usually requiring global unfolding to expose their free thiols. However, such an unfolding event also exposes the existing native disulfide bonds. Thus, the subsequent oxidation reaction to form the native protein in a disulfide-insecure intermediate competes with the intramolecular attack by the thiols of the macromolecule on its own native disulfide bonds, resulting in a large population of intermediates that are reshuffled instead of being oxidized. Under stabilizing conditions, disulfide-insecure species become long-lived kinetically trapped intermediates that slowly and only indirectly convert to the native protein through reshuffling reactions. In this study, trans-[Pt(en)(2)Cl(2)](2+), a strong oxidizing agent which has not traditionally been used in oxidative folding, was applied to shift the competition between reshuffling and oxidation reactions in des [58-110] and des [26-84], two long-lived disulfide-insecure intermediates of RNase A, and oxidize them directly under stable conditions to form the native protein. Such a successful direct conversion of kinetically trapped intermediates to the native molecule by trans-[Pt(en)(2)Cl(2)](2+) may be helpful in facilitating the oxidative folding processes of multi-disulfide-containing proteins in general.
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Affiliation(s)
- Mahesh Narayan
- Baker Laboratory of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853-1301, USA
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Gough JD, Gargano JM, Donofrio AE, Lees WJ. Aromatic Thiol pKa Effects on the Folding Rate of a Disulfide Containing Protein. Biochemistry 2003; 42:11787-97. [PMID: 14529290 DOI: 10.1021/bi034305c] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The production of proteins via recombinant DNA technology often requires the in vitro folding of inclusion bodies, which are protein aggregates. To create a more efficient redox buffer for the in vitro folding of disulfide containing proteins, aromatic thiols were investigated for their ability to increase the folding rate of scrambled RNase A. Scrambled RNase A is fully oxidized RNase A with a relatively random distribution of disulfide bonds. The importance of the thiol pK(a) value was investigated by the analysis of five para-substituted aromatic thiols with pK(a) values ranging from 5.2 to 6.6. Folding was measured at pH 6.0 where the pK(a) value of the thiols would be higher, lower, or equal to the solution pH. Thus, relative concentrations of thiol and thiolate would vary across the series. At pH 6.0, the aromatic thiols increased the folding rate of RNase A by a factor of 10-23 over that observed for glutathione, the standard additive. Under optimal conditions, the apparent rate constant increased as the thiol pK(a) value decreased. Optimal conditions occurred when the concentration of protonated thiol in solution was approximately 2 mM, although the total thiol concentration varied considerably. The importance of the concentration of protonated thiol in solution can be understood based on equilibrium effects. Kinetic studies suggest that the redox buffer participates as the nucleophile and/or the center thiol in the key rate determining thiol disulfide interchange reactions that occur during protein folding. Aromatic thiols proved to be kinetically faster and more versatile than classical aliphatic thiol redox buffers.
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Affiliation(s)
- Jonathan D Gough
- Department of Chemistry, Syracuse University, Syracuse, New York 13244, USA
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Abstract
Protein disulfide isomerase (PDI) catalyzes the formation of native disulfide pairings in secretory proteins. The ability of PDI to act as a disulfide isomerase makes it an essential enzyme in eukaryotes. PDI also fulfills other important roles. Recent studies have emphasized the importance of PDI as an oxidant in the endoplasmic reticulum. Intriguing questions remain regarding how PDI is able to catalyze both isomerization and oxidation in vivo. Studies of PDI and its homologues have led to the development of small-molecule folding catalysts that are able to accelerate disulfide isomerization in vitro and in vivo. PDI will continue to provide both an inspiration for the design of such artificial foldases and a benchmark with which to gauge the success of those designs. Here, we review current understanding of the chemistry and biology of PDI, its homologues, and small molecules that mimic its catalytic activity.
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Affiliation(s)
- Elizabeth A Kersteen
- Department of Biochemistry, University of Wisconsin--Madison, Madison, WI 53706, USA
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Woycechowsky KJ, Hook BA, Raines RT. Catalysis of protein folding by an immobilized small-molecule dithiol. Biotechnol Prog 2003; 19:1307-14. [PMID: 12892495 DOI: 10.1021/bp0257123] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The isomerization of non-native disulfide bonds often limits the rate of protein folding. Small-molecule dithiols can catalyze this process. Here, a symmetric trithiol, tris(2-mercaptoacetamidoethyl)amine, is designed on the basis of criteria known to be important for efficient catalysis of oxidative protein folding. The trithiol is synthesized and attached to two distinct solid supports via one of its three sulfhydryl groups. The resulting immobilized dithiol has an apparent disulfide E degrees ' = -208 mV, which is close to that of protein disulfide isomerase (E degrees ' = -180 mV). Incubation of the dithiol immobilized on a TentaGel resin with a protein containing non-native disulfide bonds produced only a 2-fold increase in native protein. This dithiol appeared to be inaccessible to protein. In contrast, incubation of the dithiol immobilized on styrene-glycidyl methacrylate microspheres with the non-native protein produced a 17-fold increase in native protein. This increase was 1.5-fold greater than that of a monothiol immobilized on the microspheres. Thus, the choice of both the solid support and thiol can affect catalysis of protein folding. The use of dithiol-decorated microspheres is an effective new strategy for preparative protein folding in vitro.
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Affiliation(s)
- Kenneth J Woycechowsky
- Department of Biochemistry and Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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Abstract
Protein disulfide isomerase (PDI) utilizes the active site sequence Cys-Gly-His-Cys (CGHC; E degrees ' = -180 mV) to effect thiol-disulfide interchange during oxidative protein folding. Here, the Cys-Gly-Cys-NH(2) (CGC) peptide is shown to have a disulfide reduction potential (E degrees ' = -167 mV) that is close to that of PDI. This peptide has a thiol acid dissociation constant (pK(a) = 8.7) that is lower than that of glutathione. These attributes endow the CGC peptide with substantial disulfide isomerization activity. Escherichia coli thioredoxin (Trx) utilizes the active site sequence Cys-Gly-Pro-Cys (CGPC; E degrees ' = -270 mV) to effect disulfide reduction. Removal of the proline residue from the Trx active site yields a CGC active site with a greatly destabilized disulfide bond (E degrees ' >or= -200 mV). The DeltaP34 variant retains high conformational stability and remains a substrate for thioredoxin reductase. In contrast to the reduced form of the wild-type enzyme, the reduced form of DeltaP34 Trx has disulfide isomerization activity, which is 25-fold greater than that of the CGC peptide. Thus, the rational deletion of an active site residue can bestow a new and desirable function upon an enzyme. Moreover, a CXC motif, in both a peptide and a protein, provides functional mimicry of PDI.
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Affiliation(s)
| | - Ronald T. Raines
- Department of Biochemistry, University of Wisconsin–Madison, Madison, WI 53706
- Department of Chemistry, University of Wisconsin–Madison, Madison, WI 53706
- To whom all correspondence should be addressed at the Department of Biochemistry, University of Wisconsin–Madison, 433 Babcock Drive, Madison, WI 53706-1544. Telephone: (608) 262-8588. Fax: (608) 262-3453.
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