1
|
Khan MS, Tabrez S, Bhat SA, Rabbani N, Al-Senaidy AM, Bano B. Effect of trifluoroethanol on α-crystallin: folding, aggregation, amyloid, and cytotoxicity analysis. J Mol Recognit 2015; 29:33-40. [DOI: 10.1002/jmr.2493] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Revised: 07/04/2015] [Accepted: 07/17/2015] [Indexed: 11/06/2022]
Affiliation(s)
- Mohd Shahnawaz Khan
- Department of Biochemistry, College of Science; King Saud University; Riyadh Saudi Arabia
| | - Shams Tabrez
- King Fahd Medical Research Center; King Abdulaziz University; Jeddah 21589 Saudi Arabia
| | - Sheraz Ahmed Bhat
- Department of Biochemistry, Faculty of Life Sciences; Aligarh Muslim University; Aligarh India
| | - Nayyar Rabbani
- Department of Biochemistry, College of Science; King Saud University; Riyadh Saudi Arabia
| | | | - Bilqees Bano
- Department of Biochemistry, Faculty of Life Sciences; Aligarh Muslim University; Aligarh India
| |
Collapse
|
2
|
Bhat SA, Bano B. Conformational behaviour and aggregation of chickpea cystatin in trifluoroethanol: effects of epicatechin and tannic acid. Arch Biochem Biophys 2014; 562:51-61. [PMID: 25173679 DOI: 10.1016/j.abb.2014.08.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Revised: 08/12/2014] [Accepted: 08/20/2014] [Indexed: 11/29/2022]
Abstract
Conformational alterations and aggregates of chickpea cystatin (CPC) were investigated upon sequential addition of trifluoroethanol (TFE) over a range of 0-70% v/v. CPC on 30% and 40% v/v TFE addition exhibited non-native β-sheet, altered intrinsic fluorescence, increased thioflavin T fluorescence, prominent red shifted shoulder peak in Congo red absorbance, and enhanced turbidity as well as Rayleigh scattering, suggesting the aggregate formation. TEM results confirmed the formation of fibrillar aggregates at 30% and 40% v/v TFE. On increasing concentration of TFE to 70% v/v, CPC showed retention of native-like secondary structure, increased intrinsic and ANS fluorescence. Thus our results show that favourable condition for fibrillation of CPC is in the range of 30-40% TFE. Moreover, anti-aggregational effects of polyphenols, epicatechin (EC) and tannic acid (TA) were analysed using ThT binding assay and other biophysical assays. EC and TA produced a concentration dependent decline in ThT fluorescence suggesting inhibition of the fibril formation. Furthermore, TA in comparison to EC, served as a more effective inhibitor against amyloid fibril formation of CPC. This work supports the universality of the amyloid-like aggregation not restricted to some special categories of protein and the fact that this aggregation can be prevented.
Collapse
Affiliation(s)
- Sheraz Ahmad Bhat
- Department of Biochemistry, Faculty of Life Sciences, Aligarh Muslim University, Aligarh 202002, India
| | - Bilqees Bano
- Department of Biochemistry, Faculty of Life Sciences, Aligarh Muslim University, Aligarh 202002, India.
| |
Collapse
|
3
|
Wu CL, Li BY, Wu JL, Hui CF. The activity of carp muscle-specific creatine kinase at low temperature is enhanced by decreased hydrophobicity of residue 268. Physiol Biochem Zool 2014; 87:507-16. [PMID: 24940915 DOI: 10.1086/676466] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Abstract The muscle-specific forms of creatine kinase in rabbit (RM-CK) and carp (M1-CK) exhibit different temperature-dependent functional properties. Replacing the glycine at residue 268 of RM-CK with asparagine increases the enzyme's activity at 10°C. In this study, we investigated how hydrophobicity of residue 268 affects the biochemical properties of RM-CK and M1-CK at low temperature. We generated three mutants of both RM-CK and M1-CK: Asp268, Lys268, and Leu268. The secondary structures of these mutants were similar, as revealed by their circular dichroism spectra. Similar to the Asn268 mutants, the Asp268 and Lys268 mutants of RM-CK and M1-CK exhibited higher specific activities at 10°C and pH 8.0. However, no such effect was observed for the RM-CK and M1-CK Leu268 mutants. While in the presence of cryoprotectant (sucrose or trehalose), the activities of wild-type RM-CK and M1-CK mutant enzymes with a hydrophobic residue at 268 were higher, and the effect was more profound at pH 8.0. It may be inferred that water molecules affect protein conformation around residue 268, thereby influencing protein stability at low temperature.
Collapse
Affiliation(s)
- Chih-Lu Wu
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 115, Taiwan
| | | | | | | |
Collapse
|
4
|
|
5
|
Xia Y, Ji S, Park JS, Park I, Khoi PN, Lee J, Jung YD. Inactivation and conformational changes in methyl parathion hydrolase in 2,2,2-trifluoroethanol solutions: Inactivation kinetics and molecular dynamics simulation. Process Biochem 2013. [DOI: 10.1016/j.procbio.2013.02.031] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
|
6
|
Li HL, Zhou SM, Park D, Jeong HO, Chung HY, Yang JM, Meng FG, Hu WJ. Deceleration of Arginine Kinase Refolding by Induced Helical Structures. Protein J 2012; 31:267-74. [DOI: 10.1007/s10930-012-9397-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
|
7
|
Yin SJ, Lü ZR, Park D, Chung HY, Yang JM, Zhou HM, Qian GY, Park YD. Trifluoroethanol-induced changes in activity and conformation of manganese-containing superoxide dismutase. Appl Biochem Biotechnol 2011; 166:276-88. [PMID: 22057937 DOI: 10.1007/s12010-011-9423-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Accepted: 10/18/2011] [Indexed: 11/26/2022]
Abstract
Superoxide dismutase (SOD, EC 1.15.1.1) plays an important role in antioxidant defense in organisms exposed to oxygen. However, there is a lack of research into the regulation of SOD activity and structural changes during folding, especially for SOD originating from extremophiles. We studied the inhibitory effects of trifluoroethanol (TFE) on the activity and conformation of manganese-containing SOD (Mn-SOD) from Thermus thermophilus. TFE decreased the degree of secondary structure of Mn-SOD, which directly resulted in enzyme inactivation and disrupted the tertiary structure of Mn-SOD. The kinetic studies showed that TFE-induced inactivation of Mn-SOD is a first-order reaction and that the regional Mn-contained active site is very stable compared to the overall structure. We further simulated the docking between Mn-SOD and TFE (binding energy for Dock 6.3, -9.68 kcal/mol) and predicted that the LEU9, TYR13, and HIS29 residues outside of the active site interact with TFE. Our results provide insight into the inactivation of Mn-SOD during unfolding in the presence of TFE and allow us to describe ligand binding via inhibition kinetics combined with computational predictions.
Collapse
Affiliation(s)
- Shang-Jun Yin
- College of Biological and Environmental Sciences, Zhejiang Wanli University, Ningbo 315100, People's Republic of China
| | | | | | | | | | | | | | | |
Collapse
|
8
|
The Effect of Trifluoroethanol on Tyrosinase Activity and Conformation: Inhibition Kinetics and Computational Simulations. Appl Biochem Biotechnol 2009; 160:1896-908. [DOI: 10.1007/s12010-009-8730-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2008] [Accepted: 07/26/2009] [Indexed: 10/20/2022]
|
9
|
Zou HC, Lü ZR, Wang YJ, Zhang YM, Zou F, Park YD. Effect of Cysteine Modification on Creatine Kinase Aggregation. Appl Biochem Biotechnol 2008; 152:15-28. [DOI: 10.1007/s12010-008-8282-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2007] [Accepted: 05/06/2008] [Indexed: 10/22/2022]
|
10
|
Mu H, Zhou SM, Yang JM, Meng FG, Park YD. Towards creatine kinase aggregation due to the cysteine modification at the flexible active site and refolding pathway. Int J Biol Macromol 2007; 41:439-46. [PMID: 17673285 DOI: 10.1016/j.ijbiomac.2007.06.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2007] [Revised: 05/21/2007] [Accepted: 06/11/2007] [Indexed: 10/23/2022]
Abstract
The dimeric native state of creatine kinase (CK) was aggregated at conspicuous levels during cysteine modification at the active site with using 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB) under a high enzyme concentration. Measuring the ANS-binding fluorescence revealed that the hydrophobic surface of CK was increased by cysteine modification due to the flexible active site, and this resulted in insoluble aggregation, probably via non-specific hydrophobic interactions. To determine whether the aggregates can be refolded, 3M guanidine hydrochloride (GdnHCl) was used to dissolve the aggregates into the denatured form. Refolding of the solubilized enzyme sample was then conducted, accompanied by deprivation of DTNB from the CK in the presence of DTT. As a result, CK was reactivated by up to 40% with partial recovery of the tertiary (78%) and secondary structures (77%). To further elucidate its kinetic refolding pathway, both time interval measurements and a continuous substrate reaction were performed. The results showed that the refolding behavior was similar to the manner of normal CK folding with respect to the following two-phase kinetic courses. Additionally, the rate constants for the dimerization of the unfolded CK were dependent on the enzyme concentration and this was irrespective to the DTT concentrations, suggesting the rate-limiting steps of CK reassociation. The present study will expand our insight into the flexibility of the enzyme active site, which might act as a risk factor for inducing the unfavorable aggregation and partial refolding pathway of CK, as well as inducing an intermediate-like state recovery from aggregation.
Collapse
Affiliation(s)
- Hang Mu
- Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing 100084, PR China
| | | | | | | | | |
Collapse
|
11
|
Zou HC, Yu ZH, Wang YJ, Yang JM, Zhou HM, Meng FG, Park YD. Monomeric Creatine Kinase Aggregation and Sodium Dodecyl Sulfate-cyclodextrin Assisted Refolding. J Biomol Struct Dyn 2007; 24:359-68. [PMID: 17206851 DOI: 10.1080/07391102.2007.10507125] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
The monomeric state of creatine kinase (CK) was stably captured at the equilibrium state by employing cysteine residue modifications in the presence of a denaturant, and at a partially folded state. The partially folded monomeric CK (PF-CK) was aggregated with kinetic order, which was mainly caused by the hydrophobic surface interactions between the CK subunits. The artificial chaperone, described as a SDS-cyclodextrin, was applied to prevent aggregation as well as to refold the PF-CK: SDS treatment onto the monomeric CK can significantly block aggregation and can be successfully refolded in the solutions containing cyclodextrins and DTT. Three types of cyclodextrins such as alpha-, beta-, and gamma-cyclodextrins were applied to strip SDS from the enzyme molecule, and each kinetic course was measured. The intrinsic fluorescence changes showed that reactivation occurred and this accompanied the conformational changes. The size exclusion chromatography detected the variously trapped monomeric CKs such as the thiol residue modified PF-CK, the SDS-binding PF-CK, the cyclodextrin treated PF-CK, and the DTT treated SDS-binding PF-CK. Our study demonstrated monomer CK aggregation for the first time; we also demonstrated the complex reassociation of CK during refolding with the aid of the SDS-cyclodextrin, and these pathways followed first-order kinetics.
Collapse
Affiliation(s)
- He-Chang Zou
- Department of Biological Science and Biotechnology, Tsinghua University, Beijing 100084, P. R. China
| | | | | | | | | | | | | |
Collapse
|
12
|
Shokri MM, Khajeh K, Alikhajeh J, Asoodeh A, Ranjbar B, Hosseinkhani S, Sadeghi M. Comparison of the molten globule states of thermophilic and mesophilic alpha-amylases. Biophys Chem 2006; 122:58-65. [PMID: 16516372 DOI: 10.1016/j.bpc.2005.12.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2005] [Revised: 12/17/2005] [Accepted: 12/21/2005] [Indexed: 11/23/2022]
Abstract
In recent years great interest has been generated in the process of protein folding, and the formation of intermediates during the folding process has been proven with new experimental strategies. In the present work, we have examined the molten globule state of Bacillus licheniformis alpha-amylase (BLA) by intrinsic fluorescence and circular dichroism spectra, 1-anilino naphthalene-8-sulfonate (ANS) binding and proteolytic digestion by pepsin, for comparison to its mesophilic counterpart, Bacillus amyloliquefaciens alpha-amylase (BAA). At pH 4.0, both enzymes acquire partially folded state which show characteristics of molten globule state. They unfold in such a way that their hydrophobic surfaces are exposed to a greater extent compared to the native forms. Chemical denaturation studies by guanidine hydrochloride and proteolytic digestion with pepsin show that molten globule state of BLA is more stable than from BAA. Results from gel filtration indicate that BAA has the same compactness at pH 4.0 and 7.5. However, molten globule state of BLA is less compact than its native state. The effects of polyols such as trehalose, sorbitol and glycerol on refolding of enzymes from molten globule to native state were also studied. These polyols are effective on refolding of mesophilic alpha-amylase but only slightly effect on BLA refolding. In addition, the folding pathway and stability of intermediate state of the thermophilic and the mesophilic alpha-amylases are discussed.
Collapse
Affiliation(s)
- Maryam Monsef Shokri
- Department of Biochemistry, Faculty of Sciences, Tarbiat Modares University, P.O. Box 14115-175, Tehran, Iran
| | | | | | | | | | | | | |
Collapse
|
13
|
Barrera FN, Renart ML, Molina ML, Poveda JA, Encinar JA, Fernández AM, Neira JL, González-Ros JM. Unfolding and refolding in vitro of a tetrameric, alpha-helical membrane protein: the prokaryotic potassium channel KcsA. Biochemistry 2006; 44:14344-52. [PMID: 16245951 DOI: 10.1021/bi050845t] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
2,2,2-Trifluoroethanol (TFE) effectively destabilizes the otherwise highly stable tetrameric structure of the potassium channel KcsA, a predominantly alpha-helical membrane protein [Valiyaveetil, F. I., Zhou, Y., and MacKinnon, R. (2002) Biochemistry 41, 10771-10777]. Here, we report that the effects on the protein structure of increasing concentrations of TFE in detergent solution include two successive protein concentration-dependent, cooperative transitions. In the first of such transitions, occurring at lower TFE concentrations, the tetrameric KcsA simultaneously increases the exposure of tryptophan residues to the solvent, partly loses its secondary structure, and dissociates into its constituent subunits. Under these conditions, simple dilution of the TFE permits a highly efficient refolding and tetramerization of the protein in the detergent solution. Moreover, following reconstitution into asolectin giant liposomes, the refolded protein exhibits nativelike potassium channel activity, as assessed by patch-clamp methods. Conversely, the second cooperative transition occurring at higher TFE concentrations results in the irreversible denaturation of the protein. These results are interpreted in terms of a protein and TFE concentration-dependent reversible equilibrium between the folded tetrameric protein and partly unfolded monomeric subunits, in which folding and oligomerization (or unfolding and dissociation in the other direction of the equilibrium process) are seemingly coupled processes. At higher TFE concentrations this is followed by the irreversible conversion of the unfolded monomers into a denatured protein form.
Collapse
Affiliation(s)
- Francisco N Barrera
- Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, Elche, 03202 Alicante, Spain
| | | | | | | | | | | | | | | |
Collapse
|
14
|
Wei X, Ding S, Jiang Y, Zeng XG, Zhou HM. Conformational changes and inactivation of bovine carbonic anhydrase II in 2,2,2-Trifluoroethanol solutions. BIOCHEMISTRY (MOSCOW) 2006; 71 Suppl 1:S77-82. [PMID: 16487073 DOI: 10.1134/s000629790613013x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Changes in unfolding and enzymatic activity of bovine carbonic anhydrase II (BCA II) in different concentrations of 2,2,2-trifluoroethanol (TFE) were investigated by 1-anilino-8-naphthalenesulfonate (ANS) fluorescence emission spectra, far-UV CD spectra, and enzyme activity. The results showed that the activity and conformation of BCA II changed according to the concentration of TFE. Significant aggregation was observed when BCA II was denatured at TFE concentrations between 10 and 35% (v/v). When the concentration of TFE exceeded 40%, the aggregation of BCA II was not very obvious. The activity of BCA II decreased almost to zero as the TFE concentration reached 26%. The ANS fluorescence spectra indicated the tertiary conformations of BCA II were more stable in solutions with TFE concentrations lower than 15% (v/v) and higher than 40% (v/v). Far-UV CD spectra showed that high concentrations (higher than 25%) of TFE could induce BCA II to form more alpha-helix structures and caused these structures to be in relatively stable states. The native conformation of BCA II being destroyed after its inactivity indicated that the active sites of BCA II is situated in a limited region and has more flexibility than the whole enzyme molecule.
Collapse
Affiliation(s)
- Xiang Wei
- Laboratory of Molecular Enzymology, Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing 100084, China
| | | | | | | | | |
Collapse
|
15
|
Mihov G, Grebel-Koehler D, Lübbert A, Vandermeulen GWM, Herrmann A, Klok HA, Müllen K. Polyphenylene dendrimers as scaffolds for shape-persistent multiple peptide conjugates. Bioconjug Chem 2005; 16:283-93. [PMID: 15769081 DOI: 10.1021/bc049839k] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The present work describes synthetic concepts for the coupling of peptides to polyphenylene dendrimers (PPDs). Novel functionalized cyclopentadienones have been synthesized whose Diels-Alder cycloaddition with various core molecules leads to polyphenylene dendrimers possessing (protected) amino or carboxyl groups. In addition, the resulting functionalized molecules exhibit the characteristic shape-persistence and monodispersity of PPDs. Their functions have been used for the attachment of polylysine to the dendritic scaffold. Three different methods for the decoration of dendrimers with polypeptides are presented. First, polylysine segments are grafted from the surface of the dendrimers employing alpha-amino acid N-carboxyanhydride (NCA) polymerization. Second, the C-terminal carboxyl groups of protected polypeptides are activated and then coupled to the amino groups on the surface of the PPD. Finally, cysteine terminated, unprotected peptide sequences are attached to polyphenylene dendrimers utilizing the addition of the sulfhydryl group of a cysteine to the maleimide functions on the dendrimer surface. Moreover, Diels-Alder cycloaddition of suitably functionalized cyclopentadienons to a desymmetized core molecule allows the design of a dendritic scaffold with a specific number of different anchor groups on its periphery. These approaches are important for the tailoring of new, shape-persistent, polyfunctional multiple antigen conjugates.
Collapse
Affiliation(s)
- Gueorgui Mihov
- Max Planck Institute for Polymer Research Ackermannweg 10D-55128 Mainz, Germany
| | | | | | | | | | | | | |
Collapse
|
16
|
Wang XY, Meng FG, Zhou HM. Inactivation and conformational changes of creatine kinase at low concentrations of hexafluoroisopropanol solutions. Biochem Cell Biol 2004; 81:327-33. [PMID: 14569296 DOI: 10.1139/o03-061] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Using the methods of far-ultraviolet circular dichroism (CD) spectra, fluorescence spectra, and enzyme activity assays, the inactivation and conformational changes of creatine kinase (CK) induced by 1,1,1,3,3,3-hexafluoro-2-propanol (hexafluoroisopropanol (HFIP)) of different concentrations were investigated. To avoid the aggregation of CK that occurs with high HFIP, concentrations of 0%-5% HFIP were used in this study. The CD spectra showed that HFIP concentrations above 2.5% strongly induced the formation of secondary structures of CK. No marked conformational changes were observed at low concentrations of HFIP (0%-2.5%). After incubation with 0.2% HFIP for 10 min, CK lost most of its activity. The kinetic theory of the substrate reaction during irreversible inhibition of enzyme activity described previously by Tsou was applied to study the kinetics of CK inactivation during denaturation by HFIP. The inactivation rate constants for the free enzyme and the substrate-enzyme complex were determined by Tsou's method. The results suggested that low concentrations of HFIP had a high potential to induce helices of protein and that the active site of the enzyme was situated in a limited and flexible region of the enzyme molecule that was more susceptible to the denaturant than was the protein as a whole.
Collapse
Affiliation(s)
- Xiao-Yun Wang
- College of Life Science, Shandong Agricultural University, People's Republic of China
| | | | | |
Collapse
|
17
|
Asghari SM, Khajeh K, Ranjbar B, Sajedi RH, Naderi-Manesh H. Comparative studies on trifluoroethanol (TFE) state of a thermophilic α-amylase and its mesophilic counterpart: limited proteolysis, conformational analysis, aggregation and reactivation of the enzymes. Int J Biol Macromol 2004; 34:173-9. [PMID: 15225989 DOI: 10.1016/j.ijbiomac.2004.03.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/15/2004] [Indexed: 11/21/2022]
Abstract
Detailed circular dichroism (CD), scattering and quenching studies, 1-anilinonaphthalene-8-sulfonate (ANS) binding, irreversible thermoinactivation, activity measurements and proteolytic digestion of bacterial alpha-amylases have been carried out to elucidate the effect of trifluoroethanol (TFE) on the structure of these enzymes. Under high concentrations of TFE both of the alpha-amylases, a thermostable alpha-amylase from Bacillus licheniformis (BLA) and its mesophilic counterpart from Bacillus amyloliquefaciens (BAA), acquire partially folded state characterized by an enhanced content of the secondary structure (helix) and reduced tertiary structures. According to ANS binding studies, we suggest that the TFE states induced by TFE/water mixture are not the molten globule state in the alpha-amylase folding pathway. In addition, data shows significant reversible aggregation of both enzymes in TFE/water mixtures with concentration between 10 and 60% (v/v). However, reversibility is more in case of BAA. As expected, in the absence of TFE, the thermophilic enzyme compared to mesophilic enzyme, shows a greater resistance to digestion by thermolysin. With respect to fluorescence quenching by acrylamide and potassium iodide, the thermophilic enzyme, BLA, is characterized by higher structural flexibility as compared to the BAA. On the other hand, in the presence of TFE, the enzymes are digested by protease to produce large protein fragments. It is proposed that highly helical secondary structures, acquired by BAA and BLA when dissolved in aqueous TFE, prevent binding and adaptation of the protein substrate at the active site of the protease.
Collapse
Affiliation(s)
- S Mohsen Asghari
- Department of Biochemistry and Biophysics, Faculty of Science, Tarbiat Modarres University, P.O. Box 14115-175, Tehran, Iran
| | | | | | | | | |
Collapse
|
18
|
Hahn HS, Park YD, Lee JR, Park KH, Kim TJ, Yang JM, Hahn MJ. Aggregation and folding of recombinant human creatine kinase. JOURNAL OF PROTEIN CHEMISTRY 2003; 22:563-70. [PMID: 14703990 DOI: 10.1023/b:jopc.0000005506.98513.43] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The processes of aggregation and refolding of recombinant human creatine kinase (rHCK) were studied. Most of the rHCK expressed in E. coli was present in the insoluble traction and it could be solubilized in 6 M urea solution. Unfolding of rHCK in 6 M urea showed biphasic kinetic courses (kappa1 = 6.5 x 10(-3) s(-1); kappa2 = 0.54 x 10(-3) s(-1)) as observed by maximum fluorescence wavelength change. During refolding of the rHCK dissolved in urea, significant aggregation was noticed following first-order kinetics. Aggregation rate constants were influenced by the concentration of NaCl, which increased the difference in transition-free energy (deltadeltaG), showing that stabilization of folding intermediates by NaCl could efficiently reduce the formation of insoluble aggregates. Formations of aggregate were also reduced by adjusting temperature, pH, and concentration of rHCK. Refolding of rHCK under the optimized condition which prevented the aggregation also showed multi-kinetic phases (kappa1 = 3.0 x 10(-3) s(-1); kappa2 = 0.64 x 10(-3) s(-1)). Under optimized conditions applied in this study, rHCK could correctly refold retrieving the high specific enzymatic activity.
Collapse
Affiliation(s)
- Hwa-Sun Hahn
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon 440-746, Korea
| | | | | | | | | | | | | |
Collapse
|
19
|
Ou WB, Wang RS, Zhou HM. Conformational changes and inactivation of rabbit muscle creatine kinase in dimethyl sulfoxide solutions. Biochem Cell Biol 2003; 80:427-34. [PMID: 12234096 DOI: 10.1139/o02-132] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The effects of dimethyl sulfoxide (DMSO) on creatine kinase (CK) conformation and enzymatic activity were studied by measuring activity changes, aggregation, and fluorescence spectra. The results showed that at low concentrations (< 65% v/v), DMSO had little effect on CK activity and structure. However, higher concentrations of DMSO led to CK inactivation, partial unfolding, and exposure of hydrophobic surfaces and thiol groups. DMSO caused aggregation during CK denaturation. A 75% DMSO concentration induced the most significant aggregation of CK. The CK inactivation and unfolding kinetics were single phase. The unfolding of CK was an irreversible process in the DMSO solutions. The results suggest that to a certain extent, an enzyme can maintain catalytic activity and conformation in water-organic mixture environments. Higher concentrations of DMSO affected the enzyme structure but not its active site. Inactivation occurred along with noticeable conformational change during CK denaturation. The inactivation and unfolding of CK in DMSO solutions differed from other denaturants such as guanidine, urea, and sodium dodecyl sulfate. The exposure of hydrophobic surfaces was a primary reason for the protein aggregation.
Collapse
Affiliation(s)
- Wen-Bin Ou
- Department of Biological Science and Biotechnology, Tsinghua University, Beijing, PR China
| | | | | |
Collapse
|
20
|
Zhou HW, Xu Y, Zhou HM. Activity and conformational changes of horseradish peroxidase in trifluoroethanol. Biochem Cell Biol 2002; 80:205-13. [PMID: 11989716 DOI: 10.1139/o02-003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The effect of trifluoroethanol (TFE) on horseradish peroxidase (HRP) was determined using activity assay and spectral analysis including optical absorption, circular dichroism (CD), and intrinsic fluorescence. The enzyme activity increased nearly twofold after incubation with 5-25% (v/v) concentrations of TFE. At these TFE concentrations, the tertiary structure of the protein changed little, while small changes occurred at the active site. Further increases in the TFE concentration (25-40%) decreased the enzyme activity until at 40% TFE the enzyme was completely inactivated. The alpha-helix content of the protein increased at high TFE concentrations, while near-UV CD, Soret CD, and intrinsic fluorescence indicated that the tertiary structure was destroyed. Polyacrylamide gel electrophoresis results indicated that the surface charge of the enzyme was changed at TFE concentrations greater than 20%, and increasing concentrations of TFE reduced the enzyme molecular compactness. A scheme for the unfolding of HRP in TFE was suggested based on these results. The kinetics of absorption change at 403 nm in 40% TFE followed a two-phase course. Finally, HRP incubated with TFE was more sensitive to urea denaturation, which suggested that the main effect of TFE on HRP was the disruption of hydrophobic interactions.
Collapse
Affiliation(s)
- Hong-Wei Zhou
- Department of Biological Science and Biotechnology, Tsinghua University, Beijing, PR China.
| | | | | |
Collapse
|
21
|
Köditz J, Arnold U, Ulbrich-Hofmann R. Dissecting the effect of trifluoroethanol on ribonuclease A. Subtle structural changes detected by nonspecific proteases. EUROPEAN JOURNAL OF BIOCHEMISTRY 2002; 269:3831-7. [PMID: 12153580 DOI: 10.1046/j.1432-1033.2002.03079.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
With the aim to distinguish between local and global conformational changes induced by trifluoroethanol in RNase A, spectroscopic and activity measurements in combination with proteolysis by unspecific proteases have been exploited for probing structural transitions of RNase A as a function of trifluoroethanol concentration. At > 30% (v/v) trifluoroethanol (pH 8.0; 25 degrees C), circular dichroism and fluorescence spectroscopy indicate a cooperative collapse of the tertiary structure of RNase A coinciding with the loss of its enzymatic activity. In contrast to the denaturation by guanidine hydrochloride, urea or temperature, the breakdown of the tertiary structure in trifluoroethanol is accompanied by an induction of secondary structure as detected by far-UV circular dichroism spectroscopy. Proteolysis with the nonspecific proteases subtilisin Carlsberg or proteinase K, both of which attack native RNase A at the Ala20-Ser21 peptide bond, yields refined information on conformational changes, particularly in the pretransition region. While trifluoroethanol at concentrations > 40% results in a strong increase of the rate of proteolysis and new primary cleavage sites (Tyr76-Ser77, Met79-Ser80) were identified, the rate of proteolysis at trifluoroethanol concentrations < 40% (v/v) is much smaller (up to two orders of magnitude) than that of the native RNase A. The proteolysis data point to a decreased flexibility in the surrounding of the Ala20-Ser21 peptide bond, which we attribute to subtle conformational changes of the ribonuclease A molecule. These changes, however, are too marginal to alter the overall catalytic and spectroscopic properties of ribonuclease A.
Collapse
Affiliation(s)
- Jens Köditz
- Department of Biochemistry/Biotechnology, Martin-Luther University Halle-Wittenberg, Halle, Germany
| | | | | |
Collapse
|