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Demir Ğ, Valjakka J, Turunen O, Aktaş F, Binay B. Cloning and expression heterologous alanine dehydrogenase genes: Investigation of reductive amination potential of L-alanine dehydrogenases for green synthesis of alanine derivatives. Heliyon 2024; 10:e26899. [PMID: 38463761 PMCID: PMC10923667 DOI: 10.1016/j.heliyon.2024.e26899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 02/09/2024] [Accepted: 02/21/2024] [Indexed: 03/12/2024] Open
Abstract
Unnatural amino acids (UAAs) offer significant promise in a wide range of applications, including drug discovery, the custom design of peptides and proteins, and their utility and use as markers for monitoring molecular interactions in biological research. The synthesis of UAAs presents a formidable challenge and can be classified into two primary categories: enzymatic and chemical synthesis. Notably, the enzymatic route, specifically asymmetric synthesis, emerges as a an attractive method for procuring enantiopure UAAs with high efficiency, owing to its streamlined and concise reaction mechanism. The current study investigated the reductive amination activity mechanisms of alanine dehydrogenase (L-AlaDH), sourced from a combination of newly and previously characterized microorganisms. Our principal aim was to evaluate the catalytic efficiency of these L-AlaDH enzymes concerning a range of specific ketoacids and pyruvate to ascertain their capability for facilitating the production of both natural and unnatural amino acids. After the characterization processes, mutation points for TtAlaDH were determined and as a result of the mutations, mutants that could use ketocaproate and ketovalerate more effectively than the wild type were obtained. Among the enzymes studied, MetAlaDH exhibited the highest specific activity against pyruvate, 173 U/mg, and a KM value of 1.3 mM. VlAlaDH displayed the most favourable catalytic efficiency with a rate constant of 170 s-1mM-1. On the other hand, AfAlaDH demonstrated the highest catalytic efficiency against α-ketobutyrate (34.0 s-1mM-1) and α-ketovalerate (2.7 s-1mM-1). Of the enzymes investigated in the study, TtAlaDH exhibited the highest effectiveness among bacterial enzymes in catalyzing ketocaproate with a measured catalytic efficiency of about 0.6 s-1mM-1 and a KM value of approximately 0.3 mM. These findings provide valuable insights into the substrate specificity and catalytic performance of L-AlaDHs, enhancing our understanding of their potential applications in various biocatalytic processes.
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Affiliation(s)
- Ğarip Demir
- Department of Molecular Biology and Genetics, Gebze Technical University, 41400, Gebze, Kocaeli, Turkey
| | - Jarkko Valjakka
- Faculty of Medicine and Health Technology, Tampere University, FI-33100, Tampere, Finland
| | - Ossi Turunen
- School of Forest Sciences, University of Eastern Finland, FI-80101, Joensuu, Finland
| | - Fatih Aktaş
- Faculty of Engineering, Düzce University, 81600, Düzce, Turkey
| | - Barış Binay
- Department of Bioengineering, Gebze Technical University, 41400, Gebze, Kocaeli, Turkey
- BAUZYME Biotechnology Co., Gebze Technical University Technopark, 41400, Gebze, Kocaeli, Turkey
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Dedeakayoğulları H, Valjakka J, Turunen O, Yilmazer B, Demir Ğ, Jänis J, Binay B. Application of reductive amination by heterologously expressed Thermomicrobium roseumL-alanine dehydrogenase to synthesize L-alanine derivatives. Enzyme Microb Technol 2023; 169:110265. [PMID: 37269617 DOI: 10.1016/j.enzmictec.2023.110265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 05/21/2023] [Accepted: 05/22/2023] [Indexed: 06/05/2023]
Abstract
Unnatural amino acids are unique building blocks in modern medicinal chemistry as they contain an amino and a carboxylic acid functional group, and a variable side chain. Synthesis of pure unnatural amino acids can be made through chemical modification of natural amino acids or by employing enzymes that can lead to novel molecules used in the manufacture of various pharmaceuticals. The NAD+ -dependent alanine dehydrogenase (AlaDH) enzyme catalyzes the conversion of pyruvate to L-alanine by transferring ammonium in a reversible reductive amination activity. Although AlaDH enzymes have been widely studied in terms of oxidative deamination activity, reductive amination activity studies have been limited to the use of pyruvate as a substrate. The reductive amination potential of heterologously expressed, highly pure Thermomicrobium roseum alanine dehydrogenase (TrAlaDH) was examined with regard to pyruvate, α-ketobutyrate, α-ketovalerate and α-ketocaproate. The biochemical properties were studied, which included the effects of 11 metal ions on enzymatic activity for both reactions. The enzyme accepted both derivatives of L-alanine (in oxidative deamination) and pyruvate (in reductive amination) as substrates. While the kinetic KM values associated with the pyruvate derivatives were similar to pyruvate values, the kinetic kcat values were significantly affected by the side chain increase. In contrast, KM values associated with the derivatives of L-alanine (L-α-aminobutyrate, L-norvaline, and L-norleucine) were approximately two orders of magnitude greater, which would indicate that they bind very poorly in a reactive way to the active site. The modeled enzyme structure revealed differences in the molecular orientation between L-alanine/pyruvate and L-norleucine/α-ketocaproate. The reductive activity observed would indicate that TrAlaDH has potential for the synthesis of pharmaceutically relevant amino acids.
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Affiliation(s)
- Huri Dedeakayoğulları
- Medical Biochemistry Department, Faculty of Medicine, Istinye University, 34010 Istanbul, Turkey
| | - Jarkko Valjakka
- Faculty of Medicine and Health Technology, Tampere University, FI-33100 Tampere, Finland
| | - Ossi Turunen
- School of Forest Sciences, University of Eastern Finland, FI-80101 Joensuu, Finland
| | - Berin Yilmazer
- Department of Molecular Biology and Genetics, Gebze Technical University, Gebze, 41400 Kocaeli, Turkey
| | - Ğarip Demir
- Department of Molecular Biology and Genetics, Gebze Technical University, Gebze, 41400 Kocaeli, Turkey
| | - Janne Jänis
- Department of Chemistry, University of Eastern Finland, FI-80101 Joensuu, Finland
| | - Barış Binay
- Department of Bioengineering, Gebze Technical University, Gebze, 41400 Kocaeli, Turkey; BAUZYME Biotechnology Co., Gebze Technical University Technopark, Gebze, 41400 Kocaeli, Turkey.
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Piesanen J, Valjakka J, Niemelä S, Borgenström M, Nikkari S, Hytönen V, Määttä J, Kunnas T. Hepcidin is potential regulator for renin activity. PLoS One 2022; 17:e0267343. [PMID: 35442992 PMCID: PMC9020709 DOI: 10.1371/journal.pone.0267343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 04/06/2022] [Indexed: 11/19/2022] Open
Abstract
An association between genetic variants in the genes HFE, HJV, BMP4 and arterial hypertension has been shown earlier. Proteins encoded by these genes participate in the signalling routes leading eventually to the production of the peptide hormone hepcidin. Mutations in these genes have been associated with the abnormal production of hepcidin in the body. This finding led to studies exploring the possible role of hepcidin in regulating the activity of blood pressure related renin-angiotensin system enzymes. We used molecular modelling to find out if it is possible for hepcidin to bind to the active site of the renin-angiotensin system enzymes, especially renin. Fluorometric assays were used to evaluate the inhibitory effect of hepcidin on renin as well as angiotensin converting enzymes 1 and 2. Finally, bio-layer interferometry technique was used to study hepcidin binding to renin. The molecular modelling showed that hepcidin seems to have similar binding properties to the renin active site as angiotensinogen does. Based on fluorometric enzyme activity assay, hepcidin has an inhibitory effect on renin in vitro, too. However, angiotensin converting enzymes 1 and 2 were not inhibited remarkably by hepcidin-25. In bio-layer interferometry analysis hepcidin-renin binding was concentration dependent. Our results suggest that hepcidin could act as an inhibitor to the renin. Nowadays, there is no known biological inhibitor for renin in vivo and our finding may thus have important clinical implications.
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Affiliation(s)
- Jaakko Piesanen
- Facult of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Jarkko Valjakka
- Facult of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Sanna Niemelä
- Facult of Medicine and Health Technology, Tampere University, Tampere, Finland
| | | | - Seppo Nikkari
- Facult of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Vesa Hytönen
- Facult of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Juha Määttä
- Facult of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Tarja Kunnas
- Facult of Medicine and Health Technology, Tampere University, Tampere, Finland
- * E-mail:
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Abstract
In recent years, CO2 reduction and utilization have been proposed as an innovative solution for global warming and the ever-growing energy and raw material demands. In contrast to various classical methods, including chemical, electrochemical, and photochemical methods, enzymatic methods offer a green and sustainable option for CO2 conversion. In addition, enzymatic hydrogenation of CO2 into platform chemicals could be used to produce economically useful hydrogen storage materials, making it a win-win strategy. The thermodynamic and kinetic stability of the CO2 molecule makes its utilization a challenging task. However, Nicotine adenine dinucleotide (NAD+)-dependent formate dehydrogenases (FDHs), which have high selectivity and specificity, are attractive catalysts to overcome this issue and convert CO2 into fuels and renewable chemicals. It is necessary to improve the stability, cofactor necessity, and CO2 conversion efficiency of these enzymes, such as by combining them with appropriate hybrid systems. However, metal-independent, NAD+-dependent FDHs, and their CO2 reduction activity have received limited attention to date. This review outlines the CO2 reduction ability of these enzymes as well as their properties, reaction mechanisms, immobilization strategies, and integration with electrochemical and photochemical systems for the production of formic acid or formate. The biotechnological applications of FDH, future perspectives, barriers to CO2 reduction with FDH, and aspects that must be further developed are briefly summarized. We propose that constructing hybrid systems that include NAD+-dependent FDHs is a promising approach to convert CO2 and strengthen the sustainable carbon bio-economy.
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Affiliation(s)
- Saadet Alpdağtaş
- Department of Biology, Van Yuzuncu Yil University, Tusba, Turkey
| | - Ossi Turunen
- School of Forest Sciences, University of Eastern Finland, Joensuu, Finland
| | - Jarkko Valjakka
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Barış Binay
- Department of Bioengineering, Gebze Technical University, Gebze, Turkey
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Bulut H, Valjakka J, Yuksel B, Yilmazer B, Turunen O, Binay B. Effect of Metal Ions on the Activity of Ten NAD-Dependent Formate Dehydrogenases. Protein J 2020; 39:519-530. [PMID: 33043425 DOI: 10.1007/s10930-020-09924-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/01/2020] [Indexed: 11/25/2022]
Abstract
NAD-dependent formate dehydrogenase (FDH) enzymes are frequently used in industrial and scientific applications. FDH is a reversible enzyme that reduces the NAD molecule to NADH and produces CO2 by oxidation of the formate ion, whereas it causes CO2 reduction in the reverse reaction. Some transition metal elements - Fe3+, Mo6+ and W6 + - can be found in the FDH structure of anaerobic and archaeal microorganisms, and these enzymes require cations and other redox-active cofactors for their FDH activity. While NAD-dependent FDHs do not necessarily require any metal cations, the presence of various metal cations can still affect FDH activities. To study the effect of 11 different metal ions, NAD-dependent FDH enzymes from ten different microorganisms were tested: Ancylobacter aquaticus (AaFDH), Candida boidinii (CboFDH), Candida methylica (CmFDH), Ceriporiopsis subvermispora (CsFDH), Chaetomium thermophilum (CtFDH), Moraxella sp. (MsFDH), Myceliophthora thermophila (MtFDH), Paracoccus sp. (PsFDH), Saccharomyces cerevisiae (ScFDH) and Thiobacillus sp. (TsFDH). It was found that metal ions (mainly Cu2+ and Zn2+) could have quite strong inhibition effects on several enzymes in the forward reaction, whereas several cations (Li+, Mg2+, Mn2+, Fe3+ and W6+) could increase the forward reaction of two FDHs. The highest activity increase (1.97 fold) was caused by Fe3+ in AaFDH. The effect on the reverse reaction was minimal. The modelled structures of ten FDHs showed that the active site is formed by 15 highly conserved amino acid residues spatially settling around the formate binding site in a conserved way. However, the residue differences at some of the sites close to the substrate do not explain the activity differences. The active site space is very tight, excluding water molecules, as observed in earlier studies. Structural examination indicated that smaller metal ions might be spaced close to the active site to affect the reaction. Metal ion size showed partial correlation to the effect on inhibition or activation. Affinity of the substrate may also affect the sensitivity to the metal's effect. In addition, amino acid differences on the protein surface may also be important for the metal ion effect.
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Affiliation(s)
- Huri Bulut
- Medical Biochemistry Department, Faculty of Medicine, Istinye University, Istanbul, Turkey
| | - Jarkko Valjakka
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Busra Yuksel
- Molecular Biology and Genetics Department, Istanbul Technical University, Istanbul, Turkey
| | - Berin Yilmazer
- Molecular Biology and Genetics Department, Gebze Technical University, Kocaeli, Turkey
| | - Ossi Turunen
- School of Forest Sciences, Faculty of Science and Forestry, University of Eastern Finland, Joensuu, Finland
| | - Baris Binay
- Department of Bioengineering, Gebze Technical University, Kocaeli, Turkey.
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Çakar MM, Ruupunen J, Mangas-Sanchez J, Birmingham WR, Yildirim D, Turunen O, Turner NJ, Valjakka J, Binay B. Engineered formate dehydrogenase from Chaetomium thermophilum, a promising enzymatic solution for biotechnical CO2 fixation. Biotechnol Lett 2020; 42:2251-2262. [DOI: 10.1007/s10529-020-02937-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 06/05/2020] [Indexed: 11/28/2022]
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7
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Pala U, Yelmazer B, Çorbacıoğlu M, Ruupunen J, Valjakka J, Turunen O, Binay B. Functional effects of active site mutations in NAD+-dependent formate dehydrogenases on transformation of hydrogen carbonate to formate. Protein Eng Des Sel 2018; 31:327-335. [DOI: 10.1093/protein/gzy027] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Accepted: 09/20/2018] [Indexed: 12/21/2022] Open
Affiliation(s)
- Uğur Pala
- Department of Chemistry, Gebze Technical University, Gebze, Kocaeli, Turkey
| | - Berin Yelmazer
- Department of Molecular Biology and Genetics, Gebze Technical University, Gebze, Kocaeli, Turkey
| | - Meltem Çorbacıoğlu
- Department of Chemistry, Gebze Technical University, Gebze, Kocaeli, Turkey
| | - Jouni Ruupunen
- Faculty of Medicine and Health Technology, University of Tampere, Tampereen yliopisto, Finland
| | - Jarkko Valjakka
- Faculty of Medicine and Health Technology, University of Tampere, Tampereen yliopisto, Finland
| | - Ossi Turunen
- Faculty of Science and Forestry, School of Forest Sciences, University of Eastern Finland, Joensuu, Finland
| | - Barış Binay
- Department of Bioengineering, Gebze Technical University, Gebze, Kocaeli, Turkey
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Aslan AS, Valjakka J, Ruupunen J, Yildirim D, Turner NJ, Turunen O, Binay B. Chaetomium thermophilum formate dehydrogenase has high activity in the reduction of hydrogen carbonate (HCO3 -) to formate. Protein Eng Des Sel 2016; 30:47-55. [PMID: 27887026 DOI: 10.1093/protein/gzw062] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2016] [Revised: 10/21/2016] [Accepted: 11/07/2016] [Indexed: 11/13/2022] Open
Abstract
While formate dehydrogenases (FDHs) have been used for cofactor recycling in chemoenzymatic synthesis, the ability of FDH to reduce CO2 could also be utilized in the conversion of CO2 to useful products via formate (HCOO-). In this study, we investigated the reduction of CO2 in the form of hydrogen carbonate (HCO3-) to formate by FDHs from Candida methylica (CmFDH) and Chaetomium thermophilum (CtFDH) in a NADH-dependent reaction. The catalytic performance with HCO3- as a substrate was evaluated by measuring the kinetic rates and conducting productivity assays. CtFDH showed a higher efficiency in converting HCO3- to formate than CmFDH, whereas CmFDH was better in the oxidation of formate. The pH optimum of the reduction was at pH 7-8. However, the high concentrations of HCO3- reduced the reaction rate. CtFDH was modeled in the presence of HCO3- showing that it fits to the active site. The active site setting for hydride transfer in CO2 reduction was modeled. The hydride donated by NADH would form a favorable contact to the carbon atom of HCO3-, resulting in a surplus of electrons within the molecule. This would cause the complex formed by hydrogen carbonate and the hydride to break into formate and hydroxide ions.
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Affiliation(s)
- Aşkın Sevinç Aslan
- Department of Chemistry, Gebze Technical University, Gebze 41400, Kocaeli, Turkey
| | | | | | - Deniz Yildirim
- Vocational School of Ceyhan, University of Cukurova, Adana, Turkey
| | - Nicholas J Turner
- School of Chemistry, University of Manchester, Manchester Institute of Biotechnology, 131 Princess Street, Manchester M1 7DN, UK
| | - Ossi Turunen
- Department of Biotechnology and Chemical Technology, School of Chemical Technology, Aalto University, FI-00076 Aalto, Finland
| | - Barış Binay
- Department of Bioengineering, Gebze Technical University, Gebze 41400, Kocaeli, Turkey
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Laitaoja M, Isoniemi S, Valjakka J, Mándity IM, Jänis J. Deciphering metal ion preference and primary coordination sphere robustness of a designed zinc finger with high-resolution mass spectrometry. Protein Sci 2016; 26:198-207. [PMID: 27750369 DOI: 10.1002/pro.3067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 10/13/2016] [Accepted: 10/13/2016] [Indexed: 11/10/2022]
Abstract
Small zinc finger (ZnF) motifs are promising molecular scaffolds for protein design owing to their structural robustness and versatility. Moreover, their characterization provides important insights into protein folding in general. ZnF motifs usually possess an exceptional specificity and high affinity towards Zn(II) ion to drive folding. While the Zn(II) ion is canonically coordinated by two cysteine and two histidine residues, many other coordination spheres also exist in small ZnFs, all having four amino acid ligands. Here we used high-resolution mass spectrometry to study metal ion binding specificity and primary coordination sphere robustness of a designed zinc finger, named MM1. Based on the results, MM1 possesses high specificity for zinc with sub-micromolar binding affinity. Surprisingly, MM1 retains metal ion binding affinity even in the presence of selective alanine mutations of the primary zinc coordinating amino acid residues.
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Affiliation(s)
- Mikko Laitaoja
- Department of Chemistry, University of Eastern Finland, Joensuu, FI-80101, Finland
| | - Sari Isoniemi
- Department of Chemistry, University of Eastern Finland, Joensuu, FI-80101, Finland
| | - Jarkko Valjakka
- BioMediTech, University of Tampere, Tampere, FI-33520, Finland
| | - István M Mándity
- Institute of Pharmaceutical Chemistry, University of Szeged, Szeged, H-6720, Hungary
| | - Janne Jänis
- Department of Chemistry, University of Eastern Finland, Joensuu, FI-80101, Finland
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Laitaoja M, Tossavainen H, Pihlajamaa T, Valjakka J, Viiri K, Lohi O, Permi P, Jänis J. Redox-dependent disulfide bond formation in SAP30L corepressor protein: Implications for structure and function. Protein Sci 2015; 25:572-86. [PMID: 26609676 DOI: 10.1002/pro.2849] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2015] [Accepted: 11/14/2015] [Indexed: 11/08/2022]
Abstract
Sin3A-associated protein 30-like (SAP30L) is one of the key proteins in a multi-subunit protein complex involved in transcriptional regulation via histone deacetylation. SAP30L, together with a highly homologous SAP30 as well as other SAP proteins (i.e., SAP25, SAP45, SAP130, and SAP180), is an essential component of the Sin3A corepressor complex, although its actual role has remained elusive. SAP30L is thought to function as an important stabilizing and bridging molecule in the complex and to mediate its interactions with other corepressors. SAP30L has been previously shown to contain an N-terminal Cys3 His type zinc finger (ZnF) motif, which is responsible for the key protein-protein, protein-DNA, and protein-lipid interactions. By using high-resolution mass spectrometry, we studied a redox-dependent disulfide bond formation in SAP30L ZnF as a regulatory mechanism for its structure and function. We showed that upon oxidative stress SAP30L undergoes the formation of two specific disulfide bonds, a vicinal Cys29-Cys30 and Cys38-Cys74, with a concomitant release of the coordinated zinc ion. The oxidized protein was shown to remain folded in solution and to bind signaling phospholipids. We also determined a solution NMR structure for SAP30L ZnF that showed an overall fold similar to that of SAP30, determined earlier. The NMR titration experiments with lipids and DNA showed that the binding is mediated by the C-terminal tail as well as both α-helices of SAP30L ZnF. The implications of these results for the structure and function of SAP30L are discussed.
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Affiliation(s)
- Mikko Laitaoja
- Department of Chemistry, University of Eastern Finland, Joensuu, Finland
| | | | - Tero Pihlajamaa
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | | | - Keijo Viiri
- Center for Child Health Research and Tampere University Hospital, University of Tampere, Tampere, Finland
| | - Olli Lohi
- Center for Child Health Research and Tampere University Hospital, University of Tampere, Tampere, Finland
| | - Perttu Permi
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Janne Jänis
- Department of Chemistry, University of Eastern Finland, Joensuu, Finland
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Holappa M, Valjakka J, Vaajanen A. Angiotensin(1-7) and ACE2, "The Hot Spots" of Renin-Angiotensin System, Detected in the Human Aqueous Humor. Open Ophthalmol J 2015; 9:28-32. [PMID: 25926900 PMCID: PMC4407001 DOI: 10.2174/1874364101509010028] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Revised: 03/02/2015] [Accepted: 03/02/2015] [Indexed: 12/27/2022] Open
Abstract
Background: The main purpose of the study was to establish whether essential components of the renin-angiotensin system (RAS) exist in the human aqueous humor. Methods: Forty-five patients ≥ 60 (74±7) years of age undergoing cataract surgery at Tampere University Hospital were randomly selected for the prospective study. The exclusion criterion was the use of oral antihypertensive medicine acting via renin-angiotensin system. Aqueous humor samples were taken at the beginning of normal cataract extraction. The samples were frozen and stored at -80 °C. The concentrations of intraocular endogenous RAS components Ang(1-7), ACE2, and ACE1 were measured using ELISA. Results: Concentration medians of Ang(1-7), ACE2, and ACE1 in the aqueous humor were: Ang(1-7) 4.08 ng/ml, ACE2 2.32 ng/ml and ACE1 0.35 ng/ml. The concentrations were significantly higher in glaucomatous than in non-glaucomatous eyes, ACE1 (p=0.014) and Ang(1-7) (p=0.026) vs non-glaucomatous eyes. Conclusions: Ang(1-7), ACE2 and ACE1 are found in the human aqueous humor. The observations are consistent with the conception that local tissue-RAS exists in the human eye and it might have a role in the control of intraocular pressure.
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Affiliation(s)
- Mervi Holappa
- BioMediTech, University of Tampere, Tampere, Finland
| | | | - Anu Vaajanen
- Department of Ophthalmology, Tampere University Hospital, Tampere, Finland ; SILK, Department of Ophthalmology, School of Medicine, University of Tampere, Tampere, Finland
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12
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Siltari A, Viitanen R, Kukkurainen S, Vapaatalo H, Valjakka J. Does the cis/trans configuration of peptide bonds in bioactive tripeptides play a role in ACE-1 enzyme inhibition? Biologics 2014; 8:59-65. [PMID: 24596454 PMCID: PMC3930482 DOI: 10.2147/btt.s54056] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Background The milk casein-derived bioactive tripeptides isoleucine-proline-proline (IPP) and valine-proline-proline (VPP) have been shown to prevent development of hypertension in animal models and to lower blood pressure in moderately hypertensive subjects in most but not all clinical trials. Inhibition of angiotensin-converting enzyme 1 (ACE-1) has been suggested as the explanation for these antihypertensive and beneficial vascular effects. Previously, human umbilical vein endothelial cells (HUVEC) have not been used to test ACE-1 inhibiting properties of casein derived tripeptides in vasculature. Purpose We focused on the cis/trans configurations of the peptide bonds in proline-containing tripeptides in order to discover whether the different structural properties of these peptides influence their activity in ACE-1 inhibition. We hypothesized that the configuration of proline-containing peptides plays a significant role in enzyme inhibition. Methods AutoDock 4.2 docking software was used to predict suitable peptide bond configurations of the tripeptides. Besides modeling studies, we completed ACE-1 activity measurements in vitro using HUVEC cultures. Results In HUVEC cells, both IPP and VPP inhibited ACE-1. Based on molecular docking studies, we propose that in ACE-1 inhibition IPP and VPP share a similar cis configuration between the first aliphatic (isoleucine or valine) and the second (proline) amino acid residues and more different configurations between two proline residues. In vivo experiments are needed to validate the significance of the present findings.
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Affiliation(s)
- Aino Siltari
- Institute of Biomedicine, Pharmacology, University of Helsinki, Finland
| | - Riikka Viitanen
- BioMediTech, Institute of Biomedical Technology, University of Tampere, Finland
| | - Sampo Kukkurainen
- BioMediTech, Institute of Biomedical Technology, University of Tampere, Finland
| | - Heikki Vapaatalo
- Institute of Biomedicine, Pharmacology, University of Helsinki, Finland
| | - Jarkko Valjakka
- BioMediTech, Institute of Biomedical Technology, University of Tampere, Finland
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Kukkurainen S, Määttä JA, Saeger J, Valjakka J, Vogel V, Hytönen VP. The talin–integrin interface under mechanical stress. ACTA ACUST UNITED AC 2014; 10:3217-28. [DOI: 10.1039/c4mb00341a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Interactions and force resistance of different β-integrin–talin complexes were analysed in a set of steered molecular dynamics simulations.
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Affiliation(s)
- Sampo Kukkurainen
- University of Tampere
- BioMediTech
- Tampere, Finland
- Fimlab Laboratories Ltd
- Tampere, Finland
| | - Juha A. Määttä
- University of Tampere
- BioMediTech
- Tampere, Finland
- Fimlab Laboratories Ltd
- Tampere, Finland
| | - John Saeger
- Laboratory of Applied Mechanobiology
- ETH Zurich
- Zurich, Switzerland
| | | | - Viola Vogel
- Laboratory of Applied Mechanobiology
- ETH Zurich
- Zurich, Switzerland
| | - Vesa P. Hytönen
- University of Tampere
- BioMediTech
- Tampere, Finland
- Fimlab Laboratories Ltd
- Tampere, Finland
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14
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Abstract
Zinc metalloproteins are one of the most abundant and structurally diverse proteins in nature. In these proteins, the Zn(II) ion possesses a multifunctional role as it stabilizes the fold of small zinc fingers, catalyzes essential reactions in enzymes of all six classes, or assists in the formation of biological oligomers. Previously, a number of database surveys have been conducted on zinc proteins to gain broader insights into their rich coordination chemistry. However, many of these surveys suffer from severe flaws and misinterpretations or are otherwise limited. To provide a more comprehensive, up-to-date picture on zinc coordination environments in proteins, zinc containing protein structures deposited in the Protein Data Bank (PDB) were analyzed in detail. A statistical analysis in terms of zinc coordinating amino acids, metal-to-ligand bond lengths, coordination number, and structural classification was performed, revealing coordination spheres from classical tetrahedral cysteine/histidine binding sites to more complex binuclear sites with carboxylated lysine residues. According to the results, coordination spheres of hundreds of crystal structures in the PDB could be misinterpreted due to symmetry-related molecules or missing electron densities for ligands. The analysis also revealed increasing average metal-to-ligand bond length as a function of crystallographic resolution, which should be taken into account when interrogating metal ion binding sites. Moreover, one-third of the zinc ions present in crystal structures are artifacts, merely aiding crystal formation and packing with no biological significance. Our analysis provides solid evidence that a minimal stable zinc coordination sphere is made up by four ligands and adopts a tetrahedral coordination geometry.
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Affiliation(s)
- Mikko Laitaoja
- University of Eastern Finland , Department of Chemistry, P.O. Box 111, FI-80101 Joensuu, Finland
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15
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Aidar M, Marques R, Valjakka J, Mononen N, Lehtimäki T, Parkkila S, de Souza AP, Line SRP. Effect of genetic polymorphisms in CA6 gene on the expression and catalytic activity of human salivary carbonic anhydrase VI. Caries Res 2013; 47:414-20. [PMID: 23652931 DOI: 10.1159/000350414] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 03/03/2013] [Indexed: 11/19/2022] Open
Abstract
Carbonic anhydrase isoenzyme VI (CA VI) plays an important role in the homeostasis of oral tissues participating in the processes of taste, protection of dental tissues against the loss of minerals, caries, and possibly in the formation of dental calculus in periodontal disease. This study aimed to verify the correlation between changes in the expression and activity of human salivary carbonic anhydrase VI and genetic polymorphisms in its gene (CA6). The study population consisted of 182 healthy volunteers (female and male, aged 18-22). Samples of total saliva were assayed for CA VI concentrations using a specific time-resolved immunofluorometric assay. CA VI catalytic activity was detected by a modified protocol of Kotwica et al. [J Physiol Pharmacol 2006;57(suppl 8):107-123], adapted to CA VI in saliva. Samples of genomic DNA were genotyped for polymorphisms rs2274327 (C/T), rs2274328 (A/C) and rs2274333 (A/G) by TaqMan® SNP Genotyping Assays. The concentration and catalytic activity of the salivary CA VI obtained for the different genotypes were analyzed using the Kruskal-Wallis nonparametric test and the Dunn test. The results showed that individuals with TT genotype (rs2274327) had significantly lower CA VI concentrations than the individuals with genotypes CT or CC (p < 0.05). There was also an association between polymorphism rs2274333 and salivary CA VI concentrations. There were no associations between the three polymorphisms analyzed and variations in CA VI activity. Our results suggest that polymorphisms in the CA6 gene are associated with the concentrations of secreted CA VI.
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Affiliation(s)
- M Aidar
- Department of Morphology, Piracicaba Dental School, University of Campinas-Unicamp, Sao Paulo, Brazil
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16
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Grönholm J, Vanhatupa S, Ungureanu D, Väliaho J, Laitinen T, Valjakka J, Silvennoinen O. Structure-function analysis indicates that sumoylation modulates DNA-binding activity of STAT1. BMC Biochem 2012; 13:20. [PMID: 23043228 PMCID: PMC3532225 DOI: 10.1186/1471-2091-13-20] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Accepted: 10/01/2012] [Indexed: 12/24/2022]
Abstract
Background STAT1 is an essential transcription factor for interferon-γ-mediated gene responses. A distinct sumoylation consensus site (ψKxE) 702IKTE705 is localized in the C-terminal region of STAT1, where Lys703 is a target for PIAS-induced SUMO modification. Several studies indicate that sumoylation has an inhibitory role on STAT1-mediated gene expression but the molecular mechanisms are not fully understood. Results Here, we have performed a structural and functional analysis of sumoylation in STAT1. We show that deconjugation of SUMO by SENP1 enhances the transcriptional activity of STAT1, confirming a negative regulatory effect of sumoylation on STAT1 activity. Inspection of molecular model indicated that consensus site is well exposed to SUMO-conjugation in STAT1 homodimer and that the conjugated SUMO moiety is directed towards DNA, thus able to form a sterical hindrance affecting promoter binding of dimeric STAT1. In addition, oligoprecipitation experiments indicated that sumoylation deficient STAT1 E705Q mutant has higher DNA-binding activity on STAT1 responsive gene promoters than wild-type STAT1. Furthermore, sumoylation deficient STAT1 E705Q mutant displayed enhanced histone H4 acetylation on interferon-γ-responsive promoter compared to wild-type STAT1. Conclusions Our results suggest that sumoylation participates in regulation of STAT1 responses by modulating DNA-binding properties of STAT1.
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Affiliation(s)
- Juha Grönholm
- Institute of Biomedical Technology, University of Tampere, Biokatu 8, Tampere, FIN-33014, Finland
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17
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Usvalampi A, Turunen O, Valjakka J, Pastinen O, Leisola M, Nyyssölä A. Production of l-xylose from l-xylulose using Escherichia coli l-fucose isomerase. Enzyme Microb Technol 2012; 50:71-6. [DOI: 10.1016/j.enzmictec.2011.09.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Revised: 09/11/2011] [Accepted: 09/19/2011] [Indexed: 10/17/2022]
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18
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Kallio H, Tolvanen M, Jänis J, Pan PW, Laurila E, Kallioniemi A, Kilpinen S, Tuominen VJ, Isola J, Valjakka J, Pastorekova S, Pastorek J, Parkkila S. Characterization of non-specific cytotoxic cell receptor protein 1: a new member of the lectin-type subfamily of F-box proteins. PLoS One 2011; 6:e27152. [PMID: 22087255 PMCID: PMC3210139 DOI: 10.1371/journal.pone.0027152] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2011] [Accepted: 10/11/2011] [Indexed: 11/19/2022] Open
Abstract
Our previous microarray study showed that the non-specific cytotoxic cell receptor protein 1 (Nccrp1) transcript is significantly upregulated in the gastric mucosa of carbonic anhydrase IX (CA IX)-deficient (Car9−/−) mice. In this paper, we aimed to characterize human NCCRP1 and to elucidate its relationship to CA IX. Recombinant NCCRP1 protein was expressed in Escherichia coli, and a novel polyclonal antiserum was raised against the purified full-length protein. Immunocytochemistry showed that NCCRP1 is expressed intracellularly, even though it has previously been described as a transmembrane protein. Using bioinformatic analyses, we identified orthologs of NCCRP1 in 35 vertebrate genomes, and up to five paralogs per genome. These paralogs are FBXO genes whose protein products are components of the E3 ubiquitin ligase complexes. NCCRP1 proteins have no signal peptides or transmembrane domains. NCCRP1 has mainly been studied in fish and was thought to be responsible for the cytolytic function of nonspecific cytotoxic cells (NCCs). Our analyses showed that in humans, NCCRP1 mRNA is expressed in tissues containing squamous epithelium, whereas it shows a more ubiquitous tissue expression pattern in mice. Neither human nor mouse NCCRP1 expression is specific to immune tissues. Silencing CA9 using siRNAs did not affect NCCRP1 levels, indicating that its expression is not directly regulated by CA9. Interestingly, silencing NCCRP1 caused a statistically significant decrease in the growth of HeLa cells. These studies provide ample evidence that the current name, “non-specific cytotoxic cell receptor protein 1,” is not appropriate. We therefore propose that the gene name be changed to FBXO50.
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Affiliation(s)
- Heini Kallio
- Institute of Biomedical Technology, University of Tampere, Tampere, Finland.
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19
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Bootorabi F, Jänis J, Hytönen VP, Valjakka J, Kuuslahti M, Vullo D, Niemelä O, Supuran CT, Parkkila S. Acetaldehyde-derived modifications on cytosolic human carbonic anhydrases. J Enzyme Inhib Med Chem 2011; 26:862-70. [DOI: 10.3109/14756366.2011.588227] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Fatemeh Bootorabi
- Institute of Biomedical Technology, University of Tampere and Tampere University Hospital, Tampere, Finland
- School of Medicine, University of Tampere and Tampere University Hospital, Tampere, Finland
| | - Janne Jänis
- Department of Chemistry, University of Eastern Finland, Joensuu, Finland
| | - Vesa P. Hytönen
- Institute of Biomedical Technology, University of Tampere and Tampere University Hospital, Tampere, Finland
| | - Jarkko Valjakka
- Institute of Biomedical Technology, University of Tampere and Tampere University Hospital, Tampere, Finland
| | - Marianne Kuuslahti
- Institute of Biomedical Technology, University of Tampere and Tampere University Hospital, Tampere, Finland
- School of Medicine, University of Tampere and Tampere University Hospital, Tampere, Finland
| | - Daniela Vullo
- Laboratorio di Chimica Bioinorganica, Università degli studi di Firenze, Sesto Fiorentino (Firenze), Italy
| | - Onni Niemelä
- Department of Laboratory Medicine and Medical Research Unit, Seinäjoki Central Hospital and University of Tampere, Seinäjoki, Finland
| | - Claudiu T. Supuran
- Laboratorio di Chimica Bioinorganica, Università degli studi di Firenze, Sesto Fiorentino (Firenze), Italy
| | - Seppo Parkkila
- Institute of Biomedical Technology, University of Tampere and Tampere University Hospital, Tampere, Finland
- School of Medicine, University of Tampere and Tampere University Hospital, Tampere, Finland
- Centre for Laboratory Medicine, Tampere University Hospital, Tampere, Finland
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20
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Bootorabi F, Jänis J, Smith E, Waheed A, Kukkurainen S, Hytönen V, Valjakka J, Supuran CT, Vullo D, Sly WS, Parkkila S. Analysis of a shortened form of human carbonic anhydrase VII expressed in vitro compared to the full-length enzyme. Biochimie 2010; 92:1072-80. [PMID: 20493921 DOI: 10.1016/j.biochi.2010.05.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2010] [Accepted: 05/13/2010] [Indexed: 12/22/2022]
Abstract
Carbonic anhydrase (CA) enzymes are expressed in all organs of the mammalian body where they participate in important physiological functions. CA VII is a cytosolic isozyme which may be expressed as two forms according to the recent GenBank data. We designed a present study to express and characterize the human CA VII forms: full-length CA VII and short form (predicted to lack 56 residues from the N-terminus). Reverse transcriptase PCR analysis revealed mRNAs for both CA VII forms in the human brain. These different forms were expressed as recombinant proteins to investigate their biochemical properties. The full-length CA VII was used to raise a polyclonal antiserum in a rabbit, and the antiserum was then employed in western blot analyses and immunohistochemistry of mouse tissues. Data from mass spectrometry and comparative modeling showed that CA VII protein contains a single intramolecular disulfide bridge (Cys-56 to Cys-180) which is lacking in the short form. The computer model suggested distinctly different folding for the different forms. The more exposed structure and the absence of the disulfide bridge in the short form could make this protein more susceptible to degradation. In fact, this was realized in several protein purification efforts in which the short form readily degraded during the experimental procedures. From these results, we conclude that the full-length CA VII is a predominant active form in human brain and also in other tissues. In addition to the brain, CA VII is expressed in several other organs including the stomach, duodenum, colon, liver, and skeletal muscle. The distribution pattern suggests multiple functions for CA VII in different organs.
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Affiliation(s)
- Fatemeh Bootorabi
- Institute of Medical Technology, University of Tampere and Tampere University Hospital, 33014 Tampere, Finland
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Luhtala S, Vaajanen A, Oksala O, Valjakka J, Vapaatalo H. Activities of angiotensin-converting enzymes ACE1 and ACE2 and inhibition by bioactive peptides in porcine ocular tissues. J Ocul Pharmacol Ther 2009; 25:23-8. [PMID: 19232015 DOI: 10.1089/jop.2008.0081] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
PURPOSE An active local renin-angiotensin system (RAS) has recently been found in the human eye. The aim of the present study was to compare the activities of central RAS enzymes (ACE1 and 2) in porcine ocular tissues, morphologically and physiologically close to the human eye. In addition, the effects of three ACE-inhibitory tripeptides on these enzymes were evaluated. METHODS Enucleated fresh porcine eyes were used. Activities of ACE1 and ACE2 and their inhibition by bioactive tripeptides (Ile-Pro-Pro, Val-Pro-Pro, Leu-Pro-Pro) as well as by a standard ACE-inhibitor captopril were assayed in the vitreous body, the retina and the ciliary body using fluorometric detection methods. RESULTS Activity of ACE1 as well as ACE2 was found in all tissues evaluated. ACE1 activity was markedly higher in the ciliary body (3.7 +/- 0.7 mU/mg protein) than in retina (0.2 +/- 0.02 mU/mg), whereas ACE2 activities in the ciliary body (0.2 +/- 0.02 mU/mg) and retina (0.2 +/- 0.01 mU/mg) were at the same level. In the vitreous body ACE1 activity (8.2 +/- 0.31 nmol/min/mL) was manifold compared to that of ACE2 (0.1 +/- 0.02 nmol/min/mL). The tripeptides inhibited ACE1 at one-thousandth of the concentration needed to inhibit ACE2. All peptides studied evinced about equal inhibitory activities. CONCLUSION To our knowledge the present findings constitute the first evidence of ACE2 activity in the ciliary and vitreous bodies, in addition to previously described activity in the retina. The known favorable effects of ACE2 products vs. those of ACE1 suggest a counterbalancing interaction of these two enzyme homologues in physiological regulation of ocular circulation and pressure and possible protective role in certain ophthalmic disorders such as glaucoma and diabetic retinopathy.
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Affiliation(s)
- Satu Luhtala
- Division of Biotechnology, Department of Biological and Environmental Science, University of Jyväskylä, Finland
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22
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Bootorabi F, Jänis J, Valjakka J, Isoniemi S, Vainiotalo P, Vullo D, Supuran CT, Waheed A, Sly WS, Niemelä O, Parkkila S. Modification of carbonic anhydrase II with acetaldehyde, the first metabolite of ethanol, leads to decreased enzyme activity. BMC Biochem 2008; 9:32. [PMID: 19036170 PMCID: PMC2605449 DOI: 10.1186/1471-2091-9-32] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/03/2008] [Accepted: 11/27/2008] [Indexed: 02/08/2023]
Abstract
BACKGROUND Acetaldehyde, the first metabolite of ethanol, can generate covalent modifications of proteins and cellular constituents. However, functional consequences of such modification remain poorly defined. In the present study, we examined acetaldehyde reaction with human carbonic anhydrase (CA) isozyme II, which has several features that make it a suitable target protein: It is widely expressed, its enzymatic activity can be monitored, its structural and catalytic properties are known, and it contains 24 lysine residues, which are accessible sites for aldehyde reaction. RESULTS Acetaldehyde treatment in the absence and presence of a reducing agent (NaBH3(CN)) caused shifts in the pI values of CA II. SDS-PAGE indicated a shift toward a slightly higher molecular mass. High-resolution mass spectra of CA II, measured with and without NaBH3(CN), indicated the presence of an unmodified protein, as expected. Mass spectra of CA II treated with acetaldehyde revealed a modified protein form (+26 Da), consistent with a "Schiff base" formation between acetaldehyde and one of the primary NH2 groups (e.g., in lysine side chain) in the protein structure. This reaction was highly specific, given the relative abundance of over 90% of the modified protein. In reducing conditions, each CA II molecule had reacted with 9-19 (14 on average) acetaldehyde molecules (+28 Da), consistent with further reduction of the "Schiff bases" to substituted amines (N-ethyllysine residues). The acetaldehyde-modified protein showed decreased CA enzymatic activity. CONCLUSION The acetaldehyde-derived modifications in CA II molecule may have physiological consequences in alcoholic patients.
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Affiliation(s)
- Fatemeh Bootorabi
- Institute of Medical Technology, Tampere University Hospital, 33520 Tampere, Finland.
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Hilvo M, Baranauskiene L, Salzano AM, Scaloni A, Matulis D, Innocenti A, Scozzafava A, Monti SM, Di Fiore A, De Simone G, Lindfors M, Jänis J, Valjakka J, Pastoreková S, Pastorek J, Kulomaa MS, Nordlund HR, Supuran CT, Parkkila S. Biochemical characterization of CA IX, one of the most active carbonic anhydrase isozymes. J Biol Chem 2008; 283:27799-27809. [PMID: 18703501 DOI: 10.1074/jbc.m800938200] [Citation(s) in RCA: 223] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Carbonic anhydrase IX (CA IX) is an exceptional member of the CA protein family; in addition to its classical role in pH regulation, it has also been proposed to participate in cell proliferation, cell adhesion, and tumorigenic processes. To characterize the biochemical properties of this membrane protein, two soluble recombinant forms were produced using the baculovirus-insect cell expression system. The recombinant proteins consisted of either the CA IX catalytic domain only (CA form) or the extracellular domain, which included both the proteoglycan and catalytic domains (PG + CA form). The produced proteins lacked the small transmembrane and intracytoplasmic regions of CA IX. Stopped-flow spectrophotometry experiments on both proteins demonstrated that in the excess of certain metal ions the PG + CA form exhibited the highest catalytic activity ever measured for any CA isozyme. Investigations on the oligomerization and stability of the enzymes revealed that both recombinant proteins form dimers that are stabilized by intermolecular disulfide bond(s). Mass spectrometry experiments showed that CA IX contains an intramolecular disulfide bridge (Cys(119)-Cys(299)) and a unique N-linked glycosylation site (Asn(309)) that bears high mannose-type glycan structures. Parallel experiments on a recombinant protein obtained by a mammalian cell expression system demonstrated the occurrence of an additional O-linked glycosylation site (Thr(78)) and characterized the nature of the oligosaccharide structures. This study provides novel information on the biochemical properties of CA IX and may help characterize the various cellular and pathophysiological processes in which this unique enzyme is involved.
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Affiliation(s)
- Mika Hilvo
- Institute of Medical Technology, FI-33014 Tampere, Finland.
| | - Lina Baranauskiene
- Laboratory of Biothermodynamics and Drug Design, Institute of Biotechnology, LT-02241 Vilnius, Lithuania
| | - Anna Maria Salzano
- Proteomics and Mass Spectrometry Laboratory, ISPAAM, National Research Council, 80147 Naples, Italy
| | - Andrea Scaloni
- Proteomics and Mass Spectrometry Laboratory, ISPAAM, National Research Council, 80147 Naples, Italy
| | - Daumantas Matulis
- Laboratory of Biothermodynamics and Drug Design, Institute of Biotechnology, LT-02241 Vilnius, Lithuania
| | - Alessio Innocenti
- Bioinorganic Chemistry Laboratory, University of Florence, 50019 Sesto Fiorentino (Florence), Italy
| | - Andrea Scozzafava
- Bioinorganic Chemistry Laboratory, University of Florence, 50019 Sesto Fiorentino (Florence), Italy
| | - Simona Maria Monti
- Institute of Biostructures and Bioimages, National Research Council, 80134 Naples, Italy
| | - Anna Di Fiore
- Institute of Biostructures and Bioimages, National Research Council, 80134 Naples, Italy
| | - Giuseppina De Simone
- Institute of Biostructures and Bioimages, National Research Council, 80134 Naples, Italy
| | | | - Janne Jänis
- Department of Chemistry, University of Joensuu, FI-80101 Joensuu, Finland
| | | | - Silvia Pastoreková
- Centre of Molecular Medicine, Institute of Virology, Slovak Academy of Sciences, 84505 Bratislava, Slovak Republic
| | - Jaromir Pastorek
- Centre of Molecular Medicine, Institute of Virology, Slovak Academy of Sciences, 84505 Bratislava, Slovak Republic
| | | | | | - Claudiu T Supuran
- Bioinorganic Chemistry Laboratory, University of Florence, 50019 Sesto Fiorentino (Florence), Italy
| | - Seppo Parkkila
- Institute of Medical Technology, FI-33014 Tampere, Finland; School of Medicine, University of Tampere and Tampere University Hospital, FI-33014 Tampere, Finland
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Purmonen M, Valjakka J, Takkinen K, Laitinen T, Rouvinen J. Molecular dynamics studies on the thermostability of family 11 xylanases. Protein Eng Des Sel 2007; 20:551-9. [PMID: 17977846 DOI: 10.1093/protein/gzm056] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Twelve members of the family 11 xylanases, including both mesophilic and thermophilic proteins, were studied using molecular dynamics (MD). Simulations of xylanases were carried out in an explicit water environment at four different temperatures, 300, 400, 500 and 600 K. A difference in thermotolerance between mesophilic and thermophilic xylanases became clear: thermophilic xylanases endured heat in higher simulation temperatures better than mesophilic ones. The unfolding pathways seemed to be similar for all simulations regardless of the protein. The unfolding initiates at the N-terminal region or alternatively from the alpha-helix region and proceeds to the 'finger region'. Unfolding of these regions led to denaturated structures within the 4.5 ns simulation at 600 K. The results are in agreement with experimental mutant studies. The results show clearly that the stability of the protein is not evenly distributed over the whole structure. The MD analysis suggests regions in the protein structure which are more unstable and thus potential targets for mutation experiments to improve thermostability.
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Affiliation(s)
- Mikko Purmonen
- Department of Chemistry, University of Joensuu, PO Box 111, 80101 Joensuu, Finland
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25
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Helppolainen S, Nurminen K, Määttä J, Halling K, Slotte J, Huhtala T, Liimatainen T, Ylä-Herttuala S, Airenne K, Närvänen A, Jänis J, Vainiotalo P, Valjakka J, Kulomaa M, Nordlund H. Rhizavidin from Rhizobium etli: the first natural dimer in the avidin protein family. Biochem J 2007; 405:397-405. [PMID: 17447892 PMCID: PMC2267316 DOI: 10.1042/bj20070076] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Rhizobium etli CFN42 is a symbiotic nitrogen-fixing bacterium of the common bean Phaseolus vulgaris. The symbiotic plasmid p42d of R. etli comprises a gene encoding a putative (strept)avidin-like protein, named rhizavidin. The amino acid sequence identity of rhizavidin in relation to other known avidin-like proteins is 20-30%. The amino acid residues involved in the (strept)avidin-biotin interaction are well conserved in rhizavidin. The structural and functional properties of rhizavidin were carefully studied, and we found that rhizavidin shares characteristics with bradavidin, streptavidin and avidin. However, we found that it is the first naturally occurring dimeric protein in the avidin protein family, in contrast with tetrameric (strept)avidin and bradavidin. Moreover, it possesses a proline residue after a flexible loop (GGSG) in a position close to Trp-110 in avidin, which is an important biotin-binding residue. [3H]Biotin dissociation and ITC (isothermal titration calorimetry) experiments showed dimeric rhizavidin to be a high-affinity biotin-binding protein. Its thermal stability was lower than that of avidin; although similar to streptavidin, it was insensitive to proteinase K. The immunological cross-reactivity of rhizavidin was tested with human serum samples obtained from cancer patients exposed to (strept)avidin. No significant cross-reactivity was observed. The biodistribution of the protein was studied by SPECT (single-photon emission computed tomography) imaging in rats. Similarly to avidin, rhizavidin was observed to accumulate rapidly, mainly in the liver. Evidently, rhizavidin could be used as a complement to (strept)avidin in (strept)avidin-biotin technology.
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Affiliation(s)
- Satu H. Helppolainen
- *Institute of Medical Technology, University of Tampere, FI-33014 Tampere, Finland
| | - Kirsi P. Nurminen
- *Institute of Medical Technology, University of Tampere, FI-33014 Tampere, Finland
| | - Juha A. E. Määttä
- *Institute of Medical Technology, University of Tampere, FI-33014 Tampere, Finland
| | - Katrin K. Halling
- †Department of Biochemistry and Pharmacy, Åbo Akademi University, Tykistökatu 6, FI-20520 Turku, Finland
| | - J. Peter Slotte
- †Department of Biochemistry and Pharmacy, Åbo Akademi University, Tykistökatu 6, FI-20520 Turku, Finland
| | - Tuulia Huhtala
- ‡Department of Chemistry, University of Kuopio, P.O. Box 1627, FI-70211 Kuopio, Finland
| | - Timo Liimatainen
- ‡Department of Chemistry, University of Kuopio, P.O. Box 1627, FI-70211 Kuopio, Finland
| | - Seppo Ylä-Herttuala
- §A.I. Virtanen Institute, Department of Molecular Medicine and Biotechnology, University of Kuopio, P.O. Box 1627, FI-70211 Kuopio, Finland
| | - Kari J. Airenne
- §A.I. Virtanen Institute, Department of Molecular Medicine and Biotechnology, University of Kuopio, P.O. Box 1627, FI-70211 Kuopio, Finland
| | - Ale Närvänen
- ‡Department of Chemistry, University of Kuopio, P.O. Box 1627, FI-70211 Kuopio, Finland
| | - Janne Jänis
- ∥Department of Chemistry, University of Joensuu, P.O. Box 111, FI-80101 Joensuu, Finland
| | - Pirjo Vainiotalo
- ∥Department of Chemistry, University of Joensuu, P.O. Box 111, FI-80101 Joensuu, Finland
| | - Jarkko Valjakka
- *Institute of Medical Technology, University of Tampere, FI-33014 Tampere, Finland
| | - Markku S. Kulomaa
- *Institute of Medical Technology, University of Tampere, FI-33014 Tampere, Finland
| | - Henri R. Nordlund
- *Institute of Medical Technology, University of Tampere, FI-33014 Tampere, Finland
- To whom correspondence should be addressed, at the present address NEXT Biomed Technologies Oy, Viikinkaar, 4, Fl-00790 Helsinki, Finland (email )
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Teerinen T, Valjakka J, Rouvinen J, Takkinen K. Structure-based Stability Engineering of the Mouse IgG1 Fab Fragment by Modifying Constant Domains. J Mol Biol 2006; 361:687-97. [PMID: 16876195 DOI: 10.1016/j.jmb.2006.06.073] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2006] [Revised: 06/19/2006] [Accepted: 06/21/2006] [Indexed: 11/17/2022]
Abstract
A semi-rational approach based on structural data was exploited in a search for CH1 and CL domains with improved intrinsic thermodynamic stabilities. Structural and amino acid level comparisons were carried out against known biophysically well-behaving and thermodynamically beneficial scFv and Fab fragments. A number of mutant Fab fragments were constructed by site-directed mutagenesis of regions in the CH1 and CL domains expected to be most sensitive under physical stress conditions. These mutations were located on three sites in the Fab constant domains; a mobile loop in the CH1 domain, residues surrounding the two largest solvated hydrophobic cavities located in the interface of the CH1 and CL domains and the hydrophobic core regions of both CH1 and CL. Expression levels of functional Fab fragments, denaturant-induced unfolding equilibria and circular dichroism spectroscopy were used to evaluate the relative stabilities of the wild-type and the mutant Fab fragments. The highest thermodynamic stability was reached through the mutation strategy, where the hydrophobicity and the packing density of the solvated hydrophobic cavity in the CH1/CL interface was increased by the replacement of the hydrophilic Thr178 in the CL domain by a more hydrophobic residue, valine or isoleucine. The midpoint of the transition curve from native to unfolded states of the protein, measured by fluorescence emission, occurred at concentrations of guanidine hydrochloride of 2.4 M and 2.6 M for the wild-type Fab and the most stable mutants, respectively. Our results illustrate that point mutations targeted to the CH1/CL interface were advantageous for the overall thermodynamic stability of the Fab fragment.
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Affiliation(s)
- Tuija Teerinen
- VTT Biotechnology, P.O. Box 1000, 02044 VTT Espoo, Finland
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Valjakka J, Rouvinen J. Structure of 20K endoglucanase from Melanocarpus albomyces at 1.8 A resolution. Acta Crystallogr D Biol Crystallogr 2003; 59:765-8. [PMID: 12657806 DOI: 10.1107/s0907444903002051] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2002] [Accepted: 01/23/2003] [Indexed: 11/10/2022]
Abstract
The crystal structure of the 20K endoglucanase from the thermophilic fungus Melanocarpus albomyces (Ma20k) has been determined. The structure was refined to 1.8 A resolution using data obtained at 120 K. Ma20k belongs to glycoside hydrolase family 45. The three-dimensional structures of endoglucanase V (EGV) from the fungus Humicola insolens and of an endoglucanase from H. grisea var. thermoidea have previously been determined. The overall structure of Ma20k consists of a six-stranded beta-barrel domain similar to that found previously in family 45 endoglucanases. The flexible loop between strands V and VI, which was disordered in the uncomplexed structures of the Humicola endoglucanases but was ordered in complexed structures of EGV, is found to be well ordered in the native structure of Ma20k. The structure of Ma20k allows comparison between thermophilic and mesophilic proteins of family 45 and different principles for thermostability are discussed.
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Nordman N, Valjakka J, Peräkylä M. Analysis of the binding energies of testosterone, 5alpha-dihydrotestosterone, androstenedione and dehydroepiandrosterone sulfate with an antitestosterone antibody. Proteins 2003; 50:135-43. [PMID: 12471606 DOI: 10.1002/prot.10267] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Molecular dynamics simulations and molecular mechanics-Poisson-Boltzmann surface area (MM-PBSA) free energy calculations were used to study the binding of testosterone (TES), 5alpha-dihydrotestosterone (5ADHT), androstenedione (AND), and dehydroepiandrosterone sulfate (DHEAS) to the monoclonal antitestosterone antibody 3-C(4)F(5). The relative binding free energy of TES and AND was also calculated with free energy perturbation (FEP) simulations. The antibody 3-C(4)F(5) has a relatively high affinity (3 x 10(8) M(-1)) and on overall good binding profile for testosterone but its cross-reactivity with DHEAS has been the main reason for the failure to use this antibody in clinical immunoassays. The relative binding free energies obtained with the MM-PBSA method were 1.5 kcal/mol for 5ADHT, 3.8 kcal/mol for AND, and 4.3 kcal/mol for DHEAS, as compared to TES. When a water molecule of the ligand binding site, observed in the antibody-TES crystal structure, was explicitly included in MM-PBSA calculations, the relative binding energies were 3.4, 4.9, and 5.4 kcal/mol for 5ADHT, AND, and DHEAS, respectively. The calculated numbers are in correct order but larger than the corresponding experimental energies of 1.3, 1.5, and 2.6 kcal/mol, respectively. The fact that the MM-PBSA method reproduced the relative binding free energies of DHEAS, a steroid having a negatively charged sulfate group, and the neutrally charged TES, 5ADHT, and AND in satisfactory agreement with experiment shows the robustness of the method in predicting relative binding affinities. The 800-ps FEP simulations predicted that the antibody 3-C(4)F(5) binds TES 1.3 kcal/mol tighter than AND. Computational mutagenesis of selected amino acid residues of the ligand binding site revealed that the lower affinities of AND and DHEAS as compared to TES are due to a combined effect of several residues, each contributing a small fraction to the tighter binding of TES. An exception to this is Tyr99H, whose mutation to Ala lowered the binding of DHEAS 0.7 kcal/mol more than the binding of TES. This is probably due to the hydrogen bonding interaction formed between the OH group of Tyr99H and the sulfate group of DHEAS. Computational mutagensis data also showed that the affinity of the steroids to the antitestosterone antibody 3-C(4)F(5) would be enhanced if Trp47H were repositioned so that it would make more extensive contacts with the bound ligands. In addition, the binding of steroids to antitestosterone, antiprogesterone, and antiestradiol antibodies is discussed.
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Affiliation(s)
- Nana Nordman
- Department of Chemistry, University of Kuopio, Kuopio, Finland
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Valjakka J, Hemminki A, Niemi S, Söderlund H, Takkinen K, Rouvinen J. Crystal structure of an in vitro affinity- and specificity-matured anti-testosterone Fab in complex with testosterone. Improved affinity results from small structural changes within the variable domains. J Biol Chem 2002; 277:44021-7. [PMID: 12196551 DOI: 10.1074/jbc.m208392200] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A highly selective, high affinity recombinant anti-testosterone Fab fragment has been generated by stepwise optimization of the complementarity-determining regions (CDRs) by random mutagenesis and phage display selection of a monoclonal antibody (3-C(4)F(5)). The best mutant (77 Fab) was obtained by evaluating the additivity effects of different independently selected CDR mutations. The 77 Fab contains 20 mutations and has about 40-fold increased affinity (K(d) = 3 x 10(-10) m) when compared with the wild-type (3-C(4)F(5)) Fab. To obtain structural insight into factors, which are needed to improve binding properties, we have determined the crystal structures of the mutant 77 Fab fragment with (2.15 A) and without testosterone (2.10 A) and compared these with previously determined wild-type structures. The overall testosterone binding of the 77 Fab is similar to that of the wild-type. The improved affinity and specificity of the 77 Fab fragment are due to more comprehensive packing of the testosterone with the protein, which is the result of small structural changes within the variable domains. Only one important binding site residue Glu-95 of the heavy chain CDR3 is mutated to alanine in the 77 Fab fragment. This mutation, originally selected from the phage library based on improved specificity, provides more free space for the testosterone D-ring. The light chain CDR1 of 77 Fab containing eight mutations has the most significant effect on the improved affinity, although it has no direct contact with the testosterone. The mutations of CDR-L1 cause a rearrangement in its conformation, leading to an overall fine reshaping of the binding site.
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Affiliation(s)
- Jarkko Valjakka
- Department of Chemistry, University of Joensuu, P. O. Box 111, Finland.
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Valjakka J, Takkinenz K, Teerinen T, Söderlund H, Rouvinen J. Structural insights into steroid hormone binding: the crystal structure of a recombinant anti-testosterone Fab fragment in free and testosterone-bound forms. J Biol Chem 2002; 277:4183-90. [PMID: 11707437 DOI: 10.1074/jbc.m105579200] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The monoclonal anti-testosterone antibody (3-C(4)F(5)) has a relatively high affinity (3 x 10(8) m(-1)) with an overall good specificity profile. However, the earlier characterized binding properties have shown that both the affinity and specificity of this antibody must be improved if it is intended for use in clinical immunoassays. In this paper, the crystal structures of the recombinant anti-testosterone (3-C(4)F(5)) Fab fragment have been determined in the testosterone-bound and free form at resolutions of 2.60 and 2.72 A, respectively. The high affinity binding of the (3-C(4)F(5)) Fab is mainly determined by shape complementarity between the protein and testosterone. Only one direct hydrogen bond is formed between the hydroxyl group of the testosterone D-ring and the main-chain oxygen of Gly100(J)H. The testosterone is deeply bound in a hydrophobic pocket, and the close shape complementarity is mainly formed by the third complementarity-determining regions (CDR) of the heavy and light chain. Comparison of the bound structure with the free structure indicates conformational changes in the protein upon testosterone binding. The conformational changes of the side chains of two residues Glu95H and Tyr99H in the CDR-H3 are particularly essential for the binding. Interesting similarities in the binding of different steroids were also observed upon comparison of the available structures of anti-steroid antibodies.
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Affiliation(s)
- Jarkko Valjakka
- Department of Chemistry, University of Joensuu, P. O. Box 111, 80101 Joensuu and VTT Biotechnology, P. O. Box 1500, 02044 VTT, Finland.
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Valjakka J, Hemminki A, Teerinen T, Takkinen K, Rouvinen J. X-ray studies of recombinant anti-testosterone Fab fragments: the use of PEG 3350 in crystallization. Acta Crystallogr D Biol Crystallogr 2000; 56:218-21. [PMID: 10666611 DOI: 10.1107/s0907444999016224] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Recombinant anti-testosterone wild-type Fab fragment and mutant Fab fragments with high binding selectivity developed by protein engineering have been crystallized with and without ligands. Crystals of these Fab fragments were obtained by the vapour-diffusion technique at room temperature using solutions of PEG 3350 with various biological buffers and with a wide pH range. So far, five data sets have been collected from crystals of three Fab-antigen complexes and from two uncomplexed Fab fragments, with resolutions ranging from 2.10 to 3.1 A. Crystallization conditions for Fab fragments were found by using modifications of the low ionic strength PEG 3350 series. Suitable concentrations of PEG 400, MPD and glycerol solutions for use as cryoprotectants in PEG 3350 solutions have been determined. One useful observation was that PEG 3350 is able to work alone as a cryoprotectant. The screening protocol used requires a smaller amount of protein material to achieve auspicious pre-crystals than previously. Results support the claim that PEG 3350 is more suitable for the crystallization of Fab fragments than higher molecular weight PEGs.
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Affiliation(s)
- J Valjakka
- Department of Chemistry, University of Joensuu, 80101 Joensuu, Finland.
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Abstract
The Chou-Fasman method has been widely used for predicting protein secondary structure. It is based on knowledge of the potential of amino acid residues to form alpha-helical or beta-sheet regions in proteins. Our main interest in this study was to examine the reliability of these Chou-Fasman parameters. We calculated the Chou-Fasman parameters, with 95% confidence limits, of 144 non-homologous proteins consisting of 155 chains, and a total of 33 118 amino acid residues. All of the protein chains used were X-ray structures known at a resolution of at least 2.5 A. We compared the results of our calculations with those previously done by Chou and Fasman. Our results show that Chou and Fasman classified four amino acid residues wrongly in alpha-helical regions and one in a beta-sheet region. This is so, because the confidence limits we calculated did not include the values determined by Chou and Fasman. Moreover, the confidence limit calculations contradict most of the Chou-Fasman classification of amino acid residues.
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Affiliation(s)
- J Kyngäs
- Department of Computer Science, University of Joensuu, Finland
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Kyngäs J, Valjakka J. Evolutionary Neural Networks in Quantitative Structure-Activity Relationships of Dihydrofolate Reductase Inhibitors. ACTA ACUST UNITED AC 1996. [DOI: 10.1002/qsar.19960150404] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Valjakka J, Utriainen J, berg T, Tulkki J. Direction-dependent initial-state relaxation in oxygen K x-ray emission. Phys Rev B Condens Matter 1985; 32:6892-6898. [PMID: 9936802 DOI: 10.1103/physrevb.32.6892] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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