Activity of squalene-hopene cyclases in bicontinuous microemulsions

作者：Steudle Anne K; Nestl Bettina M; Hauer Bernhard; Stubenrauch Cosima^*

来源：Colloids and Surfaces B: Biointerfaces , 2015, 135: 735-741.

DOI：10.1016/j.colsurfb.2015.08.034

• Bicontinuous microemulsion
• Activity of squalene-hopene cyclase (AacSHC)
• Circular dichroism
• Conformation of AacSHC in microemulsions
• Biocatalysis in non-conventional media

The paper at hand deals with biocatalysis in bicontinuous micro emulsions. The latter consist of a dynamic network of oil and water domains separated by a monolayer of surfactant molecules, i.e. the interfacial layer. A microemulsion with the composition buffer n-octane nonionic surfactant was tested as reaction medium for an enzyme-catalysed reaction with a focus on the conversion of hydrophobic substrates, which are difficult to convert in aqueous buffer solutions. For the study at hand, we chose to investigate the activity of the squalene-hopene cyclase from Alicyclobacillus acidocaldarius (AacSHC) towards its natural substrate squalene in bicontinuous microemulsions. Firstly, the study revealed that the activity of AacSHC depends linearly on the enzyme concentration. Secondly, a hyperbolic curve was found for the dependence of the activity on the substrate concentration and a saturation of the AacSHC at substrate concentrations above 20 mM was observed. Thirdly, the composition of the interfacial layer was found to have no significant influence on the activity or on the conformation of AacSHC. Surprisingly and unexpectedly, a distinctly enhanced selectivity towards hopene was discovered in the microemulsion. To conclude, bicontinuous microemulsions were found to be a suitable reaction medium for biocatalytic reactions with the enzyme AacSHC.

• 出版日期2015-11-1