Bauduin Pierre, Touraud Didier, Kunz Werner, Savelli Marie-Pierre, Pulvin Sylviane, Ninham Barry W
Institute of Physical and Theoretical Chemistry, University of Regensburg, 93040 Regensburg, Germany.
J Colloid Interface Sci. 2005 Dec 1;292(1):244-54. doi: 10.1016/j.jcis.2005.05.043. Epub 2005 Jul 11.
The activity of the enzyme horse radish peroxidase (HRP) is studied in a series of reverse microemulsions composed of dodecane, aqueous buffer, sodium dodecylsufate (SDS) and alcohols of the homologous series 1-butanol to 1-octanol. The HRP catalyzed reaction is the oxidation of a classical water soluble substrate, the 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) by hydrogen peroxide. In parallel electrical conductivity measurements are performed on the same solutions. The structural changes in the microemulsions, as inferred by the conductivity measurements, correlate remarkably well with the changes in the enzymatic activities. In particular it is found that (a) the maximum activity of the enzyme is always related to its optimum hydration and that this hydration can be related to the microemulsion structures, (b) the enzyme inhibition caused by the alcohols in microemulsions is a consequence of both the solubility of the alcohols in the buffer and the rigidity of the interfacial film. Consequently, it can be concluded that enzymatic activity measurements are a valuable tool to study confined systems such as microemulsions and, in particular, the amount of available hydration water. Enzymatic activities can be finely tuned by small changes in microemulsion structures, probably in a predictive way.
在由十二烷、水性缓冲液、十二烷基硫酸钠（SDS）以及从正丁醇到正辛醇的同系醇组成的一系列反相微乳液中，研究了辣根过氧化物酶（HRP）的活性。HRP催化的反应是经典水溶性底物2,2-联氮-双（3-乙基苯并噻唑啉-6-磺酸）二铵盐（ABTS）被过氧化氢氧化。同时，对相同的溶液进行电导率测量。由电导率测量推断出的微乳液结构变化与酶活性变化显著相关。特别发现：（a）酶的最大活性总是与其最佳水合作用相关，并且这种水合作用可以与微乳液结构相关；（b）微乳液中醇引起的酶抑制是醇在缓冲液中的溶解度和界面膜刚性的共同结果。因此，可以得出结论，酶活性测量是研究微乳液等受限体系，特别是可用水合水量的有价值工具。微乳液结构的微小变化可能以可预测的方式精细调节酶活性。
