Enzymes are powerful tools in organic synthesis that are able to catalyse a wide variety of selective chemical transformations under mild and environmentally friendly conditions. Enzymes such as the lipases have also found applications in the synthesis and degradation of polymeric materials. However, the use of these natural catalysts in the synthesis and the post-synthetic modification of dendrimers and hyperbranched molecules is an application of chemistry yet to be explored extensively. In this study the use of two hydrolytic enzymes, a lipase from Candida cylindracea and a cutinase from Fusarium solani pisii, were investigated in the selective cleavage of ester groups situated on the peripheral layer of two families of branched polyamides. These branched polyamides were conjugated to simple fragrances citronellol and L-menthol via ester linkages. Hydrolysis of the ester linkage between the fragrances and the branched polyamide support was carried out in aqueous buffered systems at slightly basic pH values under the optimum operative conditions for the enzymes used. These preliminary qualitative investigations revealed that partial cleavage of the ester functionalities from the branched polyamide support had occurred. However, the ability of the enzymes to interact with the substrates decreased considerably as the branching density, the rigidity of the structure and the bulkiness of the polyamide-fragrance conjugates increased.
酶是有机合成中的强大工具,能够在温和且环保的条件下催化多种选择性的
化学转化。
脂肪酶等酶类在聚合物材料的合成和降解中也找到了应用。然而,这些自然催化剂在树状聚合物和超支链分子的合成及后合成修饰中的应用仍待广泛探索。在本研究中,调查了两种
水解酶的使用,一种来自青霉菌的
脂肪酶和一种来自镰刀菌的切胶酶,用于选择性切割位于两类支链聚酰胺外围层上的酯基。这些支链聚酰胺通过酯键与简单
香料香茅醇和
L-薄荷醇结合。
香料与支链聚酰胺支撑之间酯键的
水解是在微微碱性的缓冲
水相中,在所用酶的最佳操作条件下进行的。这些初步的定性研究表明,支链聚酰胺支撑上的酯功能基团发生了部分切割。然而,随着支链密度、结构的刚性以及聚酰胺-
香料结合物的体积增大,酶与底物的相互作用能力显著降低。