A cutinase with polyester synthesis activity
A cutinase with polyester synthesis activity
复制标题
DOI：
10.1021/ma062095g
复制
发表时间：
2007-01-23
期刊：
影响因子：
5.5
通讯作者：
Gross, Richard A.
中科院分区：
文献类型：
--
作者：
Hunsen, Mo;Azim, Abul;Gross, Richard A.
聚合物合成需要新的模式，以满足日益增长的结构复杂性的要求，同时不增加环境负担。这就要求催化剂在温和条件下具有选择性。在非水介质中，一些酶已被证明对广泛的聚酯和聚碳酸酯合成反应具有惊人的活性。产生聚合物的反应包括阶梯缩合、酯交换反应和开环聚合。令人惊讶的是，大多数研究聚合反应的酶都来自脂肪酶家族，其中来自南极念珠菌的脂肪酶B是优势酶。本文首次报道了从Humicola insolens （HiC）中发现的一种角质酶具有催化聚酯合成的特殊特性。角质层酶是细胞外真菌酶，其天然功能是催化角质层中的酯键水解，角质层是高等植物角质层中发现的一种脂质聚酯。角质酶分子量约为20 kDa，是丝氨酸R/水解酶超家族中最小的成员。到目前为止，大多数已发表的关于角质酶催化的生物转化的工作都集中在聚酯的降解和小分子的酯化或酯交换上。在此，我们报道了从Novozymes获得的Humicola insoens （HiC）的角质酶在内酯开环和缩聚反应中具有良好的活性。先前的工作表明，对于聚合反应，将酶固定在高表面积的载体上是可取的。这增加了酶对高分子量底物的接近性，这些底物必须扩散到催化剂活性位点。此外，众所周知，固定化酶在固体载体往往增加其热稳定性。许多关于脂肪酶催化聚合的文献报道使用了固定在lewait珠上的来自南极念珠菌的脂肪酶B。因此，作为研究HiC合成聚酯活性的起点，该酶同样通过物理吸附固定在lewait珠上。研究了通过缩合反应来确定HiC在聚酯合成中的活性。选择了一系列链长不同的二醇和二酸（见方案1）。
New paradigms in polymer synthesis are needed to meet increasing demands for structural complexity without a concurrent increased environmental burden. This requires catalysts that are selective while operating under mild conditions. Some enzymes, in nonaqueous media, have proven to be surprisingly active for a wide range of polyester and polycarbonate synthetic reactions. Reactions leading to polymers include step-condensation, transesterification, and ring-opening polymerization. 1 Surprisingly, the majority of enzymes studied for polymerization reactions have been from the lipase family with Lipase B from Candida antarctica as the dominant enzyme. This paper reports for the first time that a cutinase from Humicola insolens (HiC) has been found to have this unusual characteristic of catalyzing polyester synthesis. Cutinases are extracellular fungal enzymes whose natural function is catalyzing the hydrolysis of ester bonds in cutin, a lipid-polyester found in the cuticle of higher plants. 2 With molecular weights of around 20 kDa, cutinases are the smallest members of the serine R/hydrolase superfamily. 3 Thus far, the majority of published work on cutinase-catalyzed biotransformations have focused on degradation of polyesters4 and on the esterification or transesterification of small molecules. 5 Herein, we report that the cutinase from Humicola insolens (HiC), obtained from Novozymes, has promising activity for lactone ring-opening and condensation polymerization reactions.Previous work has shown that, for polymerization reactions, it is preferable to immobilize enzymes on high surface area supports. 6 This increases the enzymes accessibility to high molecular weight substrates that must diffuse to and from the catalyst active site. Furthermore, it is well-known that immobilization of enzymes on solid supports often increases its thermal stability. 7 Many literature reports on lipase-catalyzed polymerizations use Lipase B from Candida antarctica immobilized on Lewatit beads. 8 Hence, as a starting point for studies of HiC activity for polyester synthesis, this enzyme was similarly immobilized by physical adsorption onto Lewatit beads. A study was performed to determine HiC activity for polyester synthesis via condensation reactions. A series of diols and diacids were selected that differ in chain length (see Scheme 1).