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Zhang Y, Liu Y, Zeng C, Shu Y, Wang X, Liang S, Wang S, Zhan R, Wang K. Characterization of two novel highly active glycoside hydrolase family 53 endo-1,4-β-galactanases and their synergism with other carbohydrases in plant polysaccharide decomposition. Int J Biol Macromol 2022; 224:653-666. [DOI: 10.1016/j.ijbiomac.2022.10.154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Revised: 10/16/2022] [Accepted: 10/18/2022] [Indexed: 11/05/2022]
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2
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Zhang X, Wang Y, Liu J, Wang W, Yan X, Zhou Y, Cui J, Yuan Y. Cloning, Expression, and Characterization of Endo-β-1,6-galactanase PoGal30 from Penicillium oxalicum. Appl Biochem Biotechnol 2022; 194:6021-6036. [PMID: 35877000 DOI: 10.1007/s12010-022-04093-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/15/2022] [Indexed: 11/25/2022]
Abstract
Because β-1,6-galactans are significant components in arabinogalactans from plant cell walls, identifying selective endo-β-1,6-galactanases is crucial to degrading these polysaccharides and to analyzing and modifying their structures. Here, we cloned and expressed in E. coli a novel endo-β-1,6-galactanase in the glycosidic hydrolase family 30 (GH30) from Penicillium oxalicum. Our recombinant PoGal30 hydrolase (1464 bp gene) that contains an N-terminal His-tag for purification by nickel affinity chromatography has a specific activity of 3.8 U/mg on the substrate de-arabinosylated gum Arabic (dGA) polysaccharide. The enzyme has 487 residues with a molecular mass of 60 kDa, an isoelectric point of 6, and functional pH and temperature optima of pH 2.5 to pH 5.0 and 40 °C, respectively. While the activity of PoGal30 is activated by Mg2+ (5 or 50 mmol/L), it is completely inhibited by Cu2+ and Fe3+ (50 mmol/L) and partially inhibited by Hg2+, EDTA, and SDS (50 mmol/L). The enzyme demonstrates high specificity towards β-1,6-galactosidic linkages in dGA, but is inactive against aryl-glycosides and galactobioses with different linkages. Using PoGal30 is, therefore, an effective approach to analyzing the fine structure of polysaccharides and preparing bioactive oligosaccharides.
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Affiliation(s)
- Xin Zhang
- College of Biological and Agricultural Engineering, Jilin University, 130022, Changchun, China
| | - Yibing Wang
- Engineering Research Center of Glycoconjugates Ministry of Education, Jilin Provincial Key Laboratory of Chemistry and Biology of Changbai Mountain Natural Drugs, School of Life Sciences, Northeast Normal University, 130024, Changchun, China
| | - Jiaqi Liu
- Engineering Research Center of Glycoconjugates Ministry of Education, Jilin Provincial Key Laboratory of Chemistry and Biology of Changbai Mountain Natural Drugs, School of Life Sciences, Northeast Normal University, 130024, Changchun, China
| | - Weiyang Wang
- Engineering Research Center of Glycoconjugates Ministry of Education, Jilin Provincial Key Laboratory of Chemistry and Biology of Changbai Mountain Natural Drugs, School of Life Sciences, Northeast Normal University, 130024, Changchun, China
| | - Xuecui Yan
- Engineering Research Center of Glycoconjugates Ministry of Education, Jilin Provincial Key Laboratory of Chemistry and Biology of Changbai Mountain Natural Drugs, School of Life Sciences, Northeast Normal University, 130024, Changchun, China
| | - Yifa Zhou
- Engineering Research Center of Glycoconjugates Ministry of Education, Jilin Provincial Key Laboratory of Chemistry and Biology of Changbai Mountain Natural Drugs, School of Life Sciences, Northeast Normal University, 130024, Changchun, China
| | - Jing Cui
- Central Laboratory, Changchun Normal University, 130031, Changchun, China
| | - Ye Yuan
- Engineering Research Center of Glycoconjugates Ministry of Education, Jilin Provincial Key Laboratory of Chemistry and Biology of Changbai Mountain Natural Drugs, School of Life Sciences, Northeast Normal University, 130024, Changchun, China.
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Wang J, Wu J, Li Z, Chen X, Liu W, Yao J. Protein engineering of CMP kinases to improve thermal stability and resultant production of 3′-sialyllactose. BIOTECHNOL BIOTEC EQ 2022. [DOI: 10.1080/13102818.2022.2095302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022] Open
Affiliation(s)
- Jingjing Wang
- School of Engineering, Anhui Agricultural University, Hefei, Anhui, PR China
| | - Jinyong Wu
- Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui, PR China
- Department of Bioenergy and Bioengineering, Huainan New Energy Research Center, Institute of Plasma Physics, Chinese Academy of Sciences, Huainan, Anhui, PR China
| | - Zhongkui Li
- Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui, PR China
- Department of Bioenergy and Bioengineering, Huainan New Energy Research Center, Institute of Plasma Physics, Chinese Academy of Sciences, Huainan, Anhui, PR China
| | - Xiangsong Chen
- Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui, PR China
- Department of Bioenergy and Bioengineering, Huainan New Energy Research Center, Institute of Plasma Physics, Chinese Academy of Sciences, Huainan, Anhui, PR China
| | - Weiwei Liu
- School of Engineering, Anhui Agricultural University, Hefei, Anhui, PR China
| | - Jianming Yao
- Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui, PR China
- Department of Bioenergy and Bioengineering, Huainan New Energy Research Center, Institute of Plasma Physics, Chinese Academy of Sciences, Huainan, Anhui, PR China
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Muderspach SJ, Fredslund F, Volf V, Poulsen JCN, Blicher TH, Clausen MH, Rasmussen KK, Krogh KBRM, Jensen K, Lo Leggio L. Engineering the substrate binding site of the hyperthermostable archaeal endo-β-1,4-galactanase from Ignisphaera aggregans. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:183. [PMID: 34530892 PMCID: PMC8447715 DOI: 10.1186/s13068-021-02025-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 08/23/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND Endo-β-1,4-galactanases are glycoside hydrolases (GH) from the GH53 family belonging to the largest clan of GHs, clan GH-A. GHs are ubiquitous and involved in a myriad of biological functions as well as being widely used industrially. Endo-β-1,4-galactanases, in particular hydrolyse galactan and arabinogalactan in pectin, a major component of the primary plant cell wall, with important functions in plant defence and application in the food and other industries. Here, we explore the family's biological diversity by characterizing the first archaeal and hyperthermophilic GH53 galactanase, and utilize it as a scaffold for engineering enzymes with different product lengths. RESULTS A galactanase gene was identified in the genome of the anaerobic hyperthermophilic archaeon Ignisphaera aggregans, and the isolated catalytic domain expressed and characterized (IaGal). IaGal presents the typical (βα)8 barrel structure of clan GH-A enzymes, with catalytic carboxylates at the end of the 4th and 7th barrel strands. Its activity optimum of at least 95 °C and melting point over 100 °C indicate extreme thermostability, a very advantageous property for industrial applications. If enzyme depletion is reduced, so is the need for re-addition, and thus costs. The main stabilizing features of IaGal compared to other structurally characterized members are π-π and cation-π interactions. The length of the substrate binding site-and thus produced oligosaccharide products-is intermediate compared to previously characterized galactanases. Variants inspired by the structural diversity in the GH53 family were rationally designed to shorten or extend the substrate binding groove, in order to modulate product length. Subsite-deleted variants produced shorter products than IaGal, as do the fungal galactanases inspiring the design. IaGal variants engineered with a longer binding site produced a less expected degradation pattern, though still different from that of wild-type IaGal. All variants remained extremely stable. CONCLUSIONS We have characterized in detail the most thermophilic endo-β-1,4-galactanase known to date and successfully engineered it to modify the degradation profile, while maintaining much of its desirable thermostability. This is an important achievement as oligosaccharide products length is an important property for industrial and natural GHs alike.
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Affiliation(s)
- Sebastian J Muderspach
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark
| | - Folmer Fredslund
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, 2800, Kgs. Lyngby, Denmark
| | - Verena Volf
- Novozymes A/S, Biologiens vej 2, 2800, Kongens Lyngby, Denmark
- Department of Genetics, Harvard Medical School, Boston, MA, USA
| | | | | | - Mads Hartvig Clausen
- Center for Nanomedicine and Theranostics, Department of Chemistry, Technical University of Denmark, Kemitorvet 207, 2800, Kgs. Lyngby, Denmark
| | - Kim Krighaar Rasmussen
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark
| | | | - Kenneth Jensen
- Novozymes A/S, Biologiens vej 2, 2800, Kongens Lyngby, Denmark.
| | - Leila Lo Leggio
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark.
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5
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Zhu F, He B, Gu F, Deng H, Chen C, Wang W, Chen N. Improvement in organic solvent resistance and activity of metalloprotease by directed evolution. J Biotechnol 2020; 309:68-74. [DOI: 10.1016/j.jbiotec.2019.12.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 12/18/2019] [Accepted: 12/19/2019] [Indexed: 12/19/2022]
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Xu Z, Cen YK, Zou SP, Xue YP, Zheng YG. Recent advances in the improvement of enzyme thermostability by structure modification. Crit Rev Biotechnol 2019; 40:83-98. [DOI: 10.1080/07388551.2019.1682963] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Zhe Xu
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
- Engineering Research Center of Bioconversion and Biopurification of Ministry of Education, Zhejiang University of Technology, Hangzhou, China
| | - Yu-Ke Cen
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
- Engineering Research Center of Bioconversion and Biopurification of Ministry of Education, Zhejiang University of Technology, Hangzhou, China
| | - Shu-Ping Zou
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
- Engineering Research Center of Bioconversion and Biopurification of Ministry of Education, Zhejiang University of Technology, Hangzhou, China
| | - Ya-Ping Xue
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
- Engineering Research Center of Bioconversion and Biopurification of Ministry of Education, Zhejiang University of Technology, Hangzhou, China
| | - Yu-Guo Zheng
- Key Laboratory of Bioorganic Synthesis of Zhejiang Province, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
- Engineering Research Center of Bioconversion and Biopurification of Ministry of Education, Zhejiang University of Technology, Hangzhou, China
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Torpenholt S, Poulsen JCN, Muderspach SJ, De Maria L, Lo Leggio L. Structure of Aspergillus aculeatus β-1,4-galactanase in complex with galactobiose. ACTA CRYSTALLOGRAPHICA SECTION F-STRUCTURAL BIOLOGY COMMUNICATIONS 2019; 75:399-404. [PMID: 31204685 DOI: 10.1107/s2053230x19005612] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Accepted: 04/24/2019] [Indexed: 11/10/2022]
Abstract
β-1,4-Galactanases are glycoside hydrolases that are involved in the degradation of pectin and belong to family 53 in the classification of glycoside hydrolases. Previous studies have elucidated the structures of several fungal and two bacterial galactanases, while biochemical studies have indicated differences in the product profiles of different members of the family. Structural studies of ligand complexes have to date been limited to the bacterial members of the family. Here, the first structure of a fungal galactanase in complex with a disaccharide is presented. Galactobiose binds to subsites -1 and -2, thus improving our understanding of ligand binding to galactanases.
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Affiliation(s)
- Søs Torpenholt
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Jens Christian N Poulsen
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | | | | | - Leila Lo Leggio
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
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8
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Sun Z, Liu Q, Qu G, Feng Y, Reetz MT. Utility of B-Factors in Protein Science: Interpreting Rigidity, Flexibility, and Internal Motion and Engineering Thermostability. Chem Rev 2019; 119:1626-1665. [PMID: 30698416 DOI: 10.1021/acs.chemrev.8b00290] [Citation(s) in RCA: 292] [Impact Index Per Article: 58.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Zhoutong Sun
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West Seventh Avenue, Tianjin Airport Economic Area, Tianjin 300308, China
| | - Qian Liu
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Ge Qu
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West Seventh Avenue, Tianjin Airport Economic Area, Tianjin 300308, China
| | - Yan Feng
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Manfred T. Reetz
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West Seventh Avenue, Tianjin Airport Economic Area, Tianjin 300308, China
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
- Chemistry Department, Philipps-University, Hans-Meerwein-Strasse 4, 35032 Marburg, Germany
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9
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Ge L, Li D, Wu T, Zhao L, Ding G, Wang Z, Xiao W. B-factor-saturation mutagenesis as a strategy to increase the thermostability of α-L-rhamnosidase from Aspergillus terreus. J Biotechnol 2018; 275:17-23. [DOI: 10.1016/j.jbiotec.2018.03.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Revised: 03/19/2018] [Accepted: 03/22/2018] [Indexed: 11/15/2022]
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10
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Broom A, Jacobi Z, Trainor K, Meiering EM. Computational tools help improve protein stability but with a solubility tradeoff. J Biol Chem 2017; 292:14349-14361. [PMID: 28710274 DOI: 10.1074/jbc.m117.784165] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 07/11/2017] [Indexed: 01/18/2023] Open
Abstract
Accurately predicting changes in protein stability upon amino acid substitution is a much sought after goal. Destabilizing mutations are often implicated in disease, whereas stabilizing mutations are of great value for industrial and therapeutic biotechnology. Increasing protein stability is an especially challenging task, with random substitution yielding stabilizing mutations in only ∼2% of cases. To overcome this bottleneck, computational tools that aim to predict the effect of mutations have been developed; however, achieving accuracy and consistency remains challenging. Here, we combined 11 freely available tools into a meta-predictor (meieringlab.uwaterloo.ca/stabilitypredict/). Validation against ∼600 experimental mutations indicated that our meta-predictor has improved performance over any of the individual tools. The meta-predictor was then used to recommend 10 mutations in a previously designed protein of moderate thermodynamic stability, ThreeFoil. Experimental characterization showed that four mutations increased protein stability and could be amplified through ThreeFoil's structural symmetry to yield several multiple mutants with >2-kcal/mol stabilization. By avoiding residues within functional ties, we could maintain ThreeFoil's glycan-binding capacity. Despite successfully achieving substantial stabilization, however, almost all mutations decreased protein solubility, the most common cause of protein design failure. Examination of the 600-mutation data set revealed that stabilizing mutations on the protein surface tend to increase hydrophobicity and that the individual tools favor this approach to gain stability. Thus, whereas currently available tools can increase protein stability and combining them into a meta-predictor yields enhanced reliability, improvements to the potentials/force fields underlying these tools are needed to avoid gaining protein stability at the cost of solubility.
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Affiliation(s)
- Aron Broom
- From the Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Zachary Jacobi
- From the Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Kyle Trainor
- From the Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
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Penicillium purpurogenum produces a highly stable endo-β-(1,4)-galactanase. Appl Biochem Biotechnol 2016; 180:1313-1327. [PMID: 27339187 DOI: 10.1007/s12010-016-2169-6] [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: 03/30/2016] [Accepted: 06/13/2016] [Indexed: 10/21/2022]
Abstract
The polysaccharides of galactose present in the pectin of the plant cell wall are degraded by endo-β-1,4-galactanases. The filamentous fungus Penicillium purpurogenum, which grows on a number of natural carbon sources, among them sugar beet pulp which contains pectin, has a gene (ppgal1) coding an endo-β-1,4-galactanase (PpGAL1). This enzyme was expressed heterologously in Pichia pastoris. It has a molecular mass of 38 kDa, a pH optimum of 4-4.5, and an optimal temperature of 60 °C. It is 100 % stable for up to 24 h at pH 4-4.5 and 40 °C. These stability properties, which exceed those from other endo-β-1,4-galactanases reported to date, make it particularly suitable for industrial processes requiring acidic conditions and temperatures up to 40 °C. PpGAL1 is, therefore, a potentially effective tool in the food industry and in other biotechnological applications.
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Engineering the thermostability of β-glucuronidase from Penicillium purpurogenum Li-3 by loop transplant. Appl Microbiol Biotechnol 2016; 100:9955-9966. [DOI: 10.1007/s00253-016-7630-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Revised: 04/18/2016] [Accepted: 05/11/2016] [Indexed: 12/21/2022]
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13
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Feng X, Tang H, Han B, Lv B, Li C. Enhancing the Thermostability of β-Glucuronidase by Rationally Redesigning the Catalytic Domain Based on Sequence Alignment Strategy. Ind Eng Chem Res 2016. [DOI: 10.1021/acs.iecr.6b00535] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- Xudong Feng
- School of Life Science, Beijing Institute of Technology, Beijing 100081, People’s Republic of China
| | - Heng Tang
- School of Life Science, Beijing Institute of Technology, Beijing 100081, People’s Republic of China
| | - Beijia Han
- School of Life Science, Beijing Institute of Technology, Beijing 100081, People’s Republic of China
| | - Bo Lv
- School of Life Science, Beijing Institute of Technology, Beijing 100081, People’s Republic of China
| | - Chun Li
- School of Life Science, Beijing Institute of Technology, Beijing 100081, People’s Republic of China
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14
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Rational Substitution of Surface Acidic Residues for Enhancing the Thermostability of Thermolysin. Appl Biochem Biotechnol 2015; 178:725-38. [DOI: 10.1007/s12010-015-1905-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 10/21/2015] [Indexed: 11/26/2022]
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15
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Torpenholt S, De Maria L, Olsson MHM, Christensen LH, Skjøt M, Westh P, Jensen JH, Lo Leggio L. Effect of mutations on the thermostability of Aspergillus aculeatus β-1,4-galactanase. Comput Struct Biotechnol J 2015; 13:256-64. [PMID: 25941560 PMCID: PMC4412966 DOI: 10.1016/j.csbj.2015.03.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 03/27/2015] [Accepted: 03/31/2015] [Indexed: 11/17/2022] Open
Abstract
New variants of β-1,4-galactanase from the mesophilic organism Aspergillus aculeatus were designed using the structure of β-1,4-galactanase from the thermophile organism Myceliophthora thermophila as a template. Some of the variants were generated using PROPKA 3.0, a validated pKa prediction tool, to test its usefulness as an enzyme design tool. The PROPKA designed variants were D182N and S185D/Q188T, G104D/A156R. Variants Y295F and G306A were designed by a consensus approach, as a complementary and validated design method. D58N was a stabilizing mutation predicted by both methods. The predictions were experimentally validated by measurements of the melting temperature (Tm ) by differential scanning calorimetry. We found that the Tm is elevated by 1.1 °C for G306A, slightly increased (in the range of 0.34 to 0.65 °C) for D182N, D58N, Y295F and unchanged or decreased for S185D/Q188T and G104D/A156R. The Tm changes were in the range predicted by PROPKA. Given the experimental errors, only the D58N and G306A show significant increase in thermodynamic stability. Given the practical importance of kinetic stability, the kinetics of the irreversible enzyme inactivation process were also investigated for the wild-type and three variants and found to be biphasic. The half-lives of thermal inactivation were approximately doubled in G306A, unchanged for D182N and, disappointingly, a lot lower for D58N. In conclusion, this study tests a new method for estimating Tm changes for mutants, adds to the available data on the effect of substitutions on protein thermostability and identifies an interesting thermostabilizing mutation, which may be beneficial also in other galactanases.
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Key Words
- AZCL-galactan, azurine-crosslinked galactan
- AaGal, β-1,4-galactanase from Aspergillus aculeatus
- CAZY, carbohydrate active enzyme database
- Computational prediction
- DSC, differential scanning calorimetry
- GH53
- MtGal, β-1,4-galactanase from Myceliophthora thermophila
- Protein design
- Thermostability
- Tm, melting temperature
- TsGal, Talaromyces stipitatus galactanase
- WT, wild type
- β-1,4-galactanase
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Affiliation(s)
- Søs Torpenholt
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | | | - Mats H M Olsson
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | | | - Michael Skjøt
- Novozymes A/S, Smørmosevej 25, 2880 Bagsværd, Denmark
| | - Peter Westh
- NSM, Research Unit for Functional Biomaterials, University of Roskilde, Universitetsvej 1, 4000 Roskilde, Denmark
| | - Jan H Jensen
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Leila Lo Leggio
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
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