Yamada Akane, Kamada Kai, Ueda Taro, Hyodo Takeo, Shimizu Yasuhiro, Soh Nobuaki
Department of Chemistry and Materials Engineering, Graduate School of Engineering, Nagasaki University Nagasaki 852-8521 Japan
Faculty of Agriculture, Saga University Saga 840-8502 Japan.
RSC Adv. 2018 Jun 4;8(36):20347-20352. doi: 10.1039/c8ra03558j. eCollection 2018 May 30.
The present study reports the effects of binding of lipase, which is an inexpensive digestive enzyme ( lipase) that catalyzes the hydrolysis reaction and is frequently utilized for artificial synthesis of a variety of organic molecules, to titanate nanosheets (TNSs) on their biocatalytic activities and stabilities under several lipase concentrations. TNSs were prepared through a hydrolysis reaction of titanium tetraisopropoxide (TTIP) with tetrabutylammonium hydroxide (TBAOH), resulting in formation of a colorless and transparent colloidal solution including TNSs with nanometric dimensions (hydrodynamic diameter: 5.6 nm). TNSs were bound to lipase molecules through electrostatic interaction in an aqueous phase at an appropriate pH, forming inorganic-bio nanohybrids (lipase-TNSs). The enzymatic reaction rate for hydrolysis of -nitrophenyl acetate (NPA) catalyzed by the lipase-TNSs, especially in diluted lipase concentrations, was significantly improved more than 8 times as compared with free lipase. On the other hand, it was confirmed that heat tolerance of lipase was also improved by binding to TNSs. These results suggest that the novel lipase-TNSs proposed here have combined enhancements of the catalytic activity and the anti-denaturation stability of lipase.
本研究报告了脂肪酶（一种廉价的消化酶，可催化水解反应，常用于多种有机分子的人工合成）与钛酸酯纳米片（TNSs）结合对其在几种脂肪酶浓度下的生物催化活性和稳定性的影响。通过四异丙醇钛（TTIP）与氢氧化四丁基铵（TBAOH）的水解反应制备了TNSs，形成了一种无色透明的胶体溶液，其中包含纳米尺寸的TNSs（流体动力学直径：5.6 nm）。在适当的pH值下，TNSs通过水相中的静电相互作用与脂肪酶分子结合，形成无机-生物纳米杂化物（脂肪酶-TNSs）。脂肪酶-TNSs催化对硝基苯乙酸（NPA）水解的酶促反应速率，特别是在稀释的脂肪酶浓度下，与游离脂肪酶相比显著提高了8倍以上。另一方面，证实了脂肪酶与TNSs结合后耐热性也得到了提高。这些结果表明，本文提出的新型脂肪酶-TNSs兼具脂肪酶催化活性和抗变性稳定性的增强。
