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论文类型：期刊论文

发表时间：2014-04-01

发表刊物：COLLOIDS AND SURFACES B-BIOINTERFACES

收录刊物：SCIE、EI、PubMed、Scopus

卷号：116

页面范围：365-371

ISSN号：0927-7765

关键字：Carbon nanotube; Immobilization; C-C bond hydrolase; Interaction mechanism; Molecular dynamics

摘要：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.