表面活性剂对T1脂肪酶活力的影响

本文研究了非离子型、阳离子型、阴离子型以及两性离子型表面活性剂对T1脂肪酶活力的影响。采用不同浓度的表面活性剂对T1脂肪酶进行处理,再以对硝基苯酚月桂酸酯作为底物,测定处理后的酶活变化。研究发现,低浓度的非离子型表面活性剂对T1都有激活作用,使其相对酶活提高50%到150%。当非离子型表面活性剂的浓度超过其临界胶束浓度,T1的活力受到不同程度的抑制,其中吐温80的抑制作用最为明显。阳离子型(CTAB)、阴离子型(N-L与SDS)和两性离子型(SB3-14)表面活性剂都对脂肪酶的酶活有强烈的抑制作用,可能是因为离子型表面活性剂的带电基团与蛋白质表面的带电氨基酸产生强烈的电荷相斥作用,导致蛋白变性而失去活力。T1脂肪酶是一类具有工业应用价值的耐热脂肪酶,研究不同类型的表面活性剂对其活力的影响,对于在不同目的下选择使用适合的表面活性剂具有重要意义。

Effect of Surfactants on T1 Lipase Activity

T1 lipase was incubated with nonionic, cationic (CTAB), anionic (N-L and sodium dodecyl sulphate [SDS]), and zwitterionic (SB3-14) surfactants at different concentrations, and subsequent changes in enzymatic activity was measured using p-nitrophenyl dodecanoate as substrate. The results showed that nonionic surfactants at low concentrations activated T1 lipase, whose relative activity increased by 50% to 150%. Conversely, T1 lipase activity was inhibited to various degrees when the concentration of nonionic surfactants exceeded their critical micelle concentration, and the most significant inhibitory effect was observed with Tween 80. The cationic, anionic, and zwitterionic surfactants strongly inhibited T1 lipase activity, probably due to strong charge repulsions produced between the charged groups of the surfactant and the charged amino acids on the protein surface, which may have led to protein denaturation and inactivation. On the other hand, SDS and SB3-14 at low concentrations slightly activated T1 lipase. Since T1 lipase is a thermostable lipase with high industrial application value, it would be useful to further investigate the effects of different surfactants on T1 lipase activity to help select suitable surfactants for different purposes.