Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, 9 Iroon Polytechniou Str., Zografou Campus, 15780, Athens, Greece.
Environment and Quality of Life Center, School of Chemical Engineering, National Technical University of Athens, 9 Iroon Polytechniou Str., Zografou Campus, 15780, Athens, Greece.
Enzyme Microb Technol. 2018 Sep;116:64-71. doi: 10.1016/j.enzmictec.2018.05.011. Epub 2018 May 18.
The catalytic behavior of a membrane-bound lipolytic enzyme (MBL-Enzyme) from the microalgae Nannochloropsis oceanica CCMP1779 was investigated. The biocatalyst showed maximum activity at 50 °C and pH 7.0, and was stable at pH 7.0 and temperatures from 40 to 60 °C. Half-lives at 60 °C, 70 °C and 80 °C were found 866.38, 150.67 and 85.57 min respectively. Thermal deactivation energy was 68.87 kJ mol. The enzyme's enthalpy (ΔΗ*), entropy (ΔS*) and Gibb's free energy (ΔG*) were in the range of 65.86-66.27 kJ mol, 132.38-140.64 J mol K and 107.80-115.81 kJ mol, respectively. Among p-nitrophenyl esters of fatty acids tested, MBL-Enzyme exhibited the highest hydrolytic activity against p-nitrophenyl palmitate (pNPP). The K and V values were found 0.051 mM and of 0.054 mmole pNP mg protein min, respectively with pNPP as substrate. The presence of Mn increased lipolytic activity by 68.25%, while Fe and Cu ions had the strongest inhibitory effect. MBL-Enzyme was stable in the presence of water miscible (66% of the initial activity in ethanol) and water immiscible (71% of the initial activity in n-octane) solvents. Myristic acid was found to be the most efficient acyl donor in esterification reactions with ethanol. Methanol was the best acyl acceptor among the primary alcohols tested.
研究了来自海洋微藻 Nannochloropsis oceanica CCMP1779 的膜结合脂肪酶（MBL-Enzyme）的催化行为。该生物催化剂在 50°C 和 pH7.0 下表现出最大活性，在 pH7.0 和 40-60°C 的温度下稳定。在 60°C、70°C 和 80°C 下的半衰期分别为 866.38、150.67 和 85.57min。热失活动力学能为 68.87kJ/mol。酶的焓（ΔΗ*）、熵（ΔS*）和吉布斯自由能（ΔG*）分别在 65.86-66.27kJ/mol、132.38-140.64J/mol/K 和 107.80-115.81kJ/mol 的范围内。在所测试的脂肪酸对硝基苯酯中，MBL-Enzyme 对对硝基苯棕榈酸酯（pNPP）表现出最高的水解活性。用 pNPP 作为底物时，K 和 V 值分别为 0.051mM 和 0.054mmole pNP/mg 蛋白/min。Mn 的存在使脂肪酶活性提高了 68.25%，而 Fe 和 Cu 离子的抑制作用最强。MBL-Enzyme 在水溶性（乙醇中初始活性的 66%）和水不溶性（正辛烷中初始活性的 71%）溶剂中稳定。在酯化反应中，肉豆蔻酸被发现是最有效的酰基供体，乙醇是所测试的伯醇中最好的酰基受体。
