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Indexed by:期刊论文

Date of Publication:2014-04-01

Journal:COLLOIDS AND SURFACES B-BIOINTERFACES

Included Journals:SCIE、EI、PubMed、Scopus

Volume:116

Page Number:365-371

ISSN No.:0927-7765

Key Words:Carbon nanotube; Immobilization; C-C bond hydrolase; Interaction mechanism; Molecular dynamics

Abstract:Carbon nanotube (CNT) has been proved to be a kind of novel support for enzyme immobilization. In this study, we tried to find the relationship between conformation and catalytic performance of immobilized enzyme. Two C-C bond hydrolases BphD and MfphA were immobilized on CNTs (SWCNT and MWCNT) via physical adsorption and covalent attachment. Among the conjugates, the immobilized BphD on chemically functionalized SWCNT (BphD-CSWCNT) retained the highest catalytic efficiency (k(cat/)k(m) value) compared to free BphD (92.9%). On the other hand, when MfphA bound to pristine SWCNT (MfphA-SWCNT), it was completely inactive. Time-resolved fluorescence spectrum indicated the formation of static ground complexes during the immobilization processes. Circular dichroism (CD) showed that the secondary structures of immobilized enzymes changed in varying degrees. In order to investigate the inhibition mechanism of MfphA by SWCNT, molecular dynamics simulation was employed to analyze the adsorption process, binding sites and time evolution of substrate tunnels. The results showed that the preferred binding sites (Trp201 and Met81) of MfphA for SWCNT blocked the main substrate access tunnel, thus making the enzyme inactive. The "tunnel-block" should be a novel possible inhibition mechanism for enzyme-nanotube conjugate. Crown Copyright (C) 2014 Published by Elsevier B.V. All rights reserved.