title: Structural and thermodynamic properties of kappa class glutathione transferase from Camelus dromedarius.
abstract: The Arabian camel, Camelus dromedarius is naturally adapted to extreme desert climate and has evolved protective mechanisms to limit oxidative stress. The mitochondrial kappa class glutathione transferase enzyme is a member of GST supergene family that represents an important enzyme group in cellular Phase II detoxification machinery and is involved in the protection against oxidative stress and xenobiotics. In the present study, C. dromedarius kappa class glutathione transferase (CdGSTK1-1) was cloned, expressed in E. coli BL21, purified and its structural, thermodynamic and unfolding pathway was investigated. The results showed that CdGSTK1-1 has unique trimeric structure, exhibits low thermostability and a complex equilibrium unfolding profile. It unfolds through three folding states with formation of thinly populated intermediate species. The melting points (Tm) of the first unfolding transition was 40.3±0.2°C and Tm of the second unfolding transition was 49.1±0.1°C. The van't Hoff enthalpy of the first and second transition were 298.7±13.2 and 616.5±2.4kJ/mol, respectively. Moreover, intrinsic fluorescence and near-UV CD studies indicates that substrate binding does not leads to major conformational changes in CdGSTK1-1.
authors.affiliation: Department of Biochemistry, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia. Electronic address: amalik@ksu.edu.sa.
authors.forename: Ajamaluddin
authors.initials: A
authors.lastname: Malik
authors.affiliation: Department of Zoology, College of Science, King Saud University, P.O. Box 22452, Riyadh 11459, Saudi Arabia; Department of Zoology and Entomology, Faculty of Science, Helwan University, Ein Helwan, Cairo, Egypt. Electronic address: dibrahim@ksu.edu.sa.
authors.forename: Dalia
authors.initials: D
authors.lastname: Fouad
authors.affiliation: Laboratory of Enzyme Technology, Department of Biotechnology, School of Food, Biotechnology and Development, Agricultural University of Athens, 75 Iera Odos Street, GR-11855-Athens, Greece. Electronic address: lambrou@aua.gr.
authors.forename: Nikolaos E
authors.initials: NE
authors.lastname: Labrou
authors.affiliation: Department of Biochemistry, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia. Electronic address: senaidy@kau.edu.sa.
authors.forename: Abdulrahman M
authors.initials: AM
authors.lastname: Al-Senaidy
authors.affiliation: Department of Biochemistry, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia. Electronic address: mdismael@hotmail.com.
authors.forename: Mohamed A
authors.initials: MA
authors.lastname: Ismael
authors.affiliation: Department of Biotechnology, Institute of Graduate Studies and Research, Alexandria University, Alexandria, Egypt. Electronic address: hesham25166@hotmail.com.
authors.forename: Hesham M
authors.initials: HM
authors.lastname: Saeed
authors.affiliation: Department of Biochemistry, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia; Molecular Biology Department, Genetic Engineering Division, National Research Centre, 33 El-Bohouth St., P.O. 12622, Dokki, Giza, Egypt. Electronic address: fataya@ksu.edu.sa.
authors.forename: Farid S
authors.initials: FS
authors.lastname: Ataya
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D002162:Camelus / Q000378:metabolism*; D003001:Cloning, Molecular; D003889:Desert Climate; D004795:Enzyme Stability; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D005982:Glutathione Transferase / Q000737:chemistry* / Q000235:genetics; D006358:Hot Temperature; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics; D017510:Protein Folding; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D058767:Protein Unfolding; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D013816:Thermodynamics
chemical_list: D007527:Isoenzymes; D011994:Recombinant Proteins; D005982:Glutathione Transferase
keywords: Camelus dromedarius; Dynamic multimode spectroscopy; Folding; Kappa class GST; Protein stability