Thebti Wajdi, Riahi Yosra, Belhadj Omrane
Laboratory of Biochemistry & Technobiology, Faculty of Science of Tunis, Tunis El Manar University, Farhat Hached University Campus, 2092 El Manar, Tunisia.
Biomed Res Int. 2016;2016:9178962. doi: 10.1155/2016/9178962. Epub 2016 Mar 16.
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).
从突尼斯温泉新分离出的嗜热栖热地芽孢杆菌LBT 77中纯化并鉴定了一种新型的热稳定、嗜碱、耐溶剂的SDS诱导丝氨酸蛋白酶。本研究首次揭示了栖热地芽孢杆菌LBT 77蛋白酶作为洗涤剂添加剂的潜力，其具有引人注目的特性。通过硫酸铵沉淀，然后进行Sephadex G - 75和DEAE - 纤维素层析，将该蛋白酶纯化至同质。它是一种分子量为30 kDa的单体酶。蛋白酶最大活性的最佳pH、温度和NaCl浓度分别为13.0、95°C和30%。Ca(2+)、Mg(2+)、DTNB、β - 巯基乙醇和SDS可刺激其活性。该蛋白酶即使在pH 13.25、90°C、30% NaCl条件下以及在高浓度亲水性、疏水性溶剂存在的情况下也极其稳定。与离子型、非离子型和市售洗涤剂的高兼容性证实了其作为清洁产品添加剂的实用性。蛋白酶的动力学和热力学特性显示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)，以及ΔG (⁎) = 56.5 kJ mol(-¹)。
