Regulation of catalytic behaviour of hydrolases through interactions with functionalized carbon-based nanomaterials
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The interaction of enzymes with carbon-based nanomaterials (CBNs) is crucial for the function of biomolecules and therefore for the design and development of effective nanobiocatalytic systems. In this study, the effect of functionalized CBNs, such as graphene oxide (GO) and multi-wall carbon nanotubes (CNTs), on the catalytic behaviour of various hydrolases of biotechnological interest was monitored and the interactions between CBNs and proteins were investigated. The enzyme–nanomaterial interactions significantly affect the catalytic behaviour of enzymes, resulting in an increase up to 60 % of the catalytic efficiency of lipases and a decrease up to 30 % of the esterase. Moreover, the use of CNTs and GO derivatives, especially those that are amine-functionalized, led to increased thermal stability of most the hydrolases tested. Fluorescence and circular dichroism studies indicated that the altered catalytic behaviour of enzymes in the presence of CBNs arises from specific enzyme–nanomaterial interactions, which can lead to significant conformational changes. In the case of lipases, the conformational changes led to a more active and rigid structure, while in the case of esterases this led to destabilization and unfolding. Kinetic and spectroscopic studies indicated that the extent of the interactions between CBNs and hydrolases can be mainly controlled by the functionalization of nanomaterials than by their geometry.
KeywordsLipase Esterase Interaction Carbon nanotubes Graphene oxide
Bacillus subtilis esterase
Pseudozyma (Candida) antarctica lipase A
Pseudozyma (Candida) antarctica lipase B
Oxidized carbon nanotubes
Amine-functionalized carbon nanotubes
Candida rugosa lipase
Amine-functionalized graphene oxide
Pseudomonas fluorescens esterase I
Part of this study was supported from the Program IKYDA 2010 for the Promotion of the Exchange and Scientific Cooperation between Greece and Germany (IKY, Athens, Greece and DAAD, Bonn, Germany). We are grateful to A.S. Politou from the Laboratory of Biological Chemistry, Medical School, University of Ioannina, for the use of CD facilities. I.V.P. is very thankful to the Bodossakis Foundation for the financial support.