Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur 176061, Himachal Pradesh, India; Department of Biotechnology, Guru Nanak Dev University, Amritsar 143005, Punjab, India.
Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur 176061, Himachal Pradesh, India.
Int J Biol Macromol. 2021 May 15;179:576-585. doi: 10.1016/j.ijbiomac.2021.03.019. Epub 2021 Mar 5.
Superoxide dismutases are the enzymes involved in dismutation of superoxide radicals into oxygen and hydrogen peroxide. The present work reports a thermostable Fe/Mn SOD of Geobacillus sp. strain PCH100 (GsSOD) isolated from glacial soil. Purified recombinant GsSOD is a dimeric protein of ~57 kDa that exhibited highest activity at a temperature of 10 °C and pH of 7.8. Maximum enzyme velocity and Michaelis constant of the GsSOD were 1098.90 units/mg and 0.62 μM, respectively. At 80 °C, thermal inactivation rate constant and half-life of GsSOD were 3.33 × 10 min and 208 min, respectively. Interestingly, GsSOD tolerated a temperature of 100 °C and 130 °C up to 15 min and 5 min, respectively. Circular dichroism and differential scanning calorimetry confirmed thermostable nature of GsSOD. Apoenzyme of GsSOD regained enzymatic activity in the presence of Fe and Mn as metal ion cofactors. GsSOD was stable under varying concentrations of chemicals, namely ethylenediaminetetraacetic acid, potassium cyanide, hydrogen peroxide, chloroform-ethanol, 3-[(3-cholamidopropyl)-dimethylammonio]-1-propanesulfonate, Tween-20, Triton X-100, urea, and guanidine hydrochloride. The enzyme exhibited >70% activity in presence of 10 mM metal ions. Owing to its thermostable nature and resistance to chemical inhibitors, GsSOD is a potential enzyme for industrial applications.
超氧化物歧化酶是参与将超氧自由基歧化为氧和过氧化氢的酶。本工作报道了从冰川土壤中分离的芽孢杆菌属菌株 PCH100（GsSOD）的一种耐热 Fe/Mn SOD。纯化的重组 GsSOD 是一种约 57 kDa 的二聚体蛋白，在 10°C 和 pH 7.8 的温度下表现出最高的活性。GsSOD 的最大酶速度和米氏常数分别为 1098.90 单位/mg 和 0.62 μM。在 80°C 下，GsSOD 的热失活速率常数和半衰期分别为 3.33×10-4 min 和 208 min。有趣的是，GsSOD 可以耐受 100°C 和 130°C 的温度，分别高达 15 min 和 5 min。圆二色性和差示扫描量热法证实了 GsSOD 的热稳定性。GsSOD 的脱辅基酶在 Fe 和 Mn 作为金属离子辅因子的存在下恢复了酶活性。GsSOD 在各种化学物质的浓度下都很稳定，如乙二胺四乙酸、氰化钾、过氧化氢、氯仿-乙醇、3-[(3-胆酰胺丙基)-二甲基氨基]-1-丙磺酸、吐温-20、Triton X-100、脲和盐酸胍。该酶在存在 10 mM 金属离子时表现出>70%的活性。由于其耐热性质和对化学抑制剂的抗性，GsSOD 是一种有潜力的工业应用酶。
