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

Autor:	D.B.R.K. Gupta Udatha, Hao Zhou, Evangelos Topakas, Lisbeth Olsson, Paul Christakopoulos, Christian Thörn
Rok vydání:	2013
Předmět:	Immobilized enzyme biology Chemistry Process Chemistry and Technology Active site Bioengineering Mesoporous silica Biochemistry Combinatorial chemistry Catalysis Enzyme structure Enzyme assay MOPS Enzyme binding chemistry.chemical_compound Feruloyl esterase biology.protein Organic chemistry
Zdroj:	Journal of Molecular Catalysis B: Enzymatic. 93:65-72
ISSN:	1381-1177
Popis:	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.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::e1d948acf413be466a56f49d45f3f5f2 https://doi.org/10.1016/j.molcatb.2013.04.011 Zobrazit plný text záznamu Full Text from ScienceDirect