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Understanding the pH-dependent immobilization efficacy of feruloyl esterase-C on mesoporous silica and its structure activity changes

Christian Thörn (Institutionen för kemi- och bioteknik, Industriell Bioteknik ) ; D.B.R.K. Gupta Udatha (Institutionen för kemi- och bioteknik, Industriell Bioteknik ) ; H. Zhou ; P. Christakopoulos ; E. Topakas ; Lisbeth Olsson (Institutionen för kemi- och bioteknik, Industriell Bioteknik )
Journal of Molecular Catalysis B-Enzymatic (1381-1177). Vol. 93 (2013), p. 65-72.
[Artikel, refereegranskad vetenskaplig]

The purpose of the present investigation was to study the pH dependence of both the immobilization process and the enzyme activity of a feruloyl esterase (FoFaeC from Fusarium oxysporum) immobilized in mesoporous silica. This was done by interpreting experimental results with theoretical molecular modeling of the enzyme structure. Modeling of the 3D structure of the enzyme together with calculations of the electrostatic surface potential showed that changes in the electrostatic potential of the protein surface were correlated with the pH dependence of the immobilization process. High immobilization yields were associated with an increase in pH. The transesterification activity of both immobilized and free enzyme was studied at different values of pH and the optimal pH of the immobilized enzyme was found to be one unit lower than that for the free enzyme. The surface charge distribution around the binding pocket was identified as being a crucial factor for the accessibility of the active site of the immobilized enzyme, indicating that the orientation of the enzyme inside the pores is pH dependent. Interestingly, it was observed that the immobilization pH affects the specific activity, irrespective of the changes in reaction pH. This was identified as a pH memory effect for the immobilized enzyme. On the other hand, a change in product selectivity of the immobilized enzyme was also observed when the transesterification reaction was run in MOPS buffer instead of citrate phosphate buffer. Molecular docking studies revealed that the MOPS buffer molecule can bind to the enzyme binding pocket, and can therefore be assumed to modulate the product selectivity of the immobilized enzyme toward transesterification.

Nyckelord: Enzyme immobilization, Feruloyl esterases, Mesoporous silica, Molecular simulations, Docking



Denna post skapades 2013-08-02. Senast ändrad 2015-03-30.
CPL Pubid: 180436

 

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Institutioner (Chalmers)

Institutionen för kemi- och bioteknik, Industriell Bioteknik (2008-2014)

Ämnesområden

Industriell bioteknik

Chalmers infrastruktur

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Immobilization of feruloyl esterases in mesoporous silica