Abstract
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.
Highlights
The majority of the enzymes operate at physiological temperatures, in neutral aqueous media, and in the absence of substrate functional group protection [1]
Lipases are a class of enzymes employed frequently in organic synthesis and catalyse the hydrolysis of esters in aqueous medium and the esterification of carboxylic acids in organic solvents [6]
Following the pioneering work of Seebach and co-workers [9], the post-synthetic modification of dendritic surfaces was investigated by mean of two hydrolytic enzymes, a lipase and a cutinase
Summary
The majority of the enzymes operate at physiological temperatures, in neutral aqueous media, and in the absence of substrate functional group protection [1]. In many cases enzymes display chemo-, regio- and enantioselectivity, and possess high turnover values, thereby rendering these natural catalysts very appealing, especially in the pharmaceutical and agrochemical industries [2]. The use of enzymes as catalysts has been exploited in areas such as asymmetric synthesis [3]. Enzymes are used frequently in the protection/deprotection of sugars and peptides, where selective masking of α-amino groups, carboxy groups and various side chains represent the most important problems in peptide chemistry [5]. Lipases are a class of enzymes employed frequently in organic synthesis and catalyse the hydrolysis of esters in aqueous medium and the esterification of carboxylic acids in organic solvents [6]. Numerous lipases have been used frequently in the synthesis, transformation and biodegradation studies of polymeric materials [7]
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