title: Purification and Characterization of a New Thermostable, Haloalkaline, Solvent Stable, and Detergent Compatible Serine Protease from Geobacillus toebii Strain LBT 77.
abstract: A new thermostable, haloalkaline, solvent stable SDS-induced serine protease was purified and characterized from a thermophilic Geobacillus toebii LBT 77 newly isolated from a Tunisian hot spring. This study reveals the potential of the protease from Geobacillus toebii LBT 77 as an additive to detergent with spectacular proprieties described for the first time. The protease was purified to homogeneity by ammonium sulfate precipitation followed by Sephadex G-75 and DEAE-Cellulose chromatography. It was a monomeric enzyme with molecular weight of 30 kDa. The optimum pH, temperature, and NaCl for maximum protease activity were 13.0, 95°C, and 30%, respectively. Activity was stimulated by Ca(2+), Mg(2+), DTNB, β-mercaptoethanol, and SDS. The protease was extremely stable even at pH 13.25, 90°C, and 30% NaCl and in the presence of hydrophilic, hydrophobic solvents at high concentrations. The high compatibility with ionic, nonionic, and commercial detergents confirms the utility as an additive to cleaning products. Kinetic and thermodynamic characterization of protease revealed K m = 1 mg mL(-1), V max = 217.5 U mL(-1), K cat/K m = 99 mg mL(-1) S(-1), E a = 51.5 kJ mol(-1), and ΔG (⁎) = 56.5 kJ mol(-1).
authors.affiliation: Laboratory of Biochemistry & Technobiology, Faculty of Science of Tunis, Tunis El Manar University, Farhat Hached University Campus, 2092 El Manar, Tunisia.
authors.forename: Wajdi
authors.identifier: 0000-0002-0471-2502
authors.initials: W
authors.lastname: Thebti
authors.affiliation: Laboratory of Biochemistry & Technobiology, Faculty of Science of Tunis, Tunis El Manar University, Farhat Hached University Campus, 2092 El Manar, Tunisia.
authors.forename: Yosra
authors.initials: Y
authors.lastname: Riahi
authors.affiliation: Laboratory of Biochemistry & Technobiology, Faculty of Science of Tunis, Tunis El Manar University, Farhat Hached University Campus, 2092 El Manar, Tunisia.
authors.forename: Omrane
authors.initials: O
authors.lastname: Belhadj
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000302:isolation & purification* / Q000378:metabolism; D004795:Enzyme Stability; D056506:Geobacillus / Q000201:enzymology*; D006358:Hot Temperature; D009930:Organic Chemicals; D057057:Serine Proteases / Q000737:chemistry* / Q000302:isolation & purification* / Q000378:metabolism; D013501:Surface-Active Agents
chemical_list: D001426:Bacterial Proteins; D009930:Organic Chemicals; D013501:Surface-Active Agents; D057057:Serine Proteases