标题：Spectroscopic investigations on the effect of N-Acetyl-L-cysteine-Capped CdTe Quantum Dots on catalase
作者：Sun, Haoyu; Yang, Bingjun; Cui, Erqian; Liu, Rutao
作者机构：[Sun, Haoyu; Yang, Bingjun; Cui, Erqian; Liu, Rutao] Shandong Univ, China Amer CRC Environm & Hlth, Sch Environm Sci & Engn, Jinan 250100, Shandong, P 更多
通讯作者地址：[Liu, RT]Shandong Univ, China Amer CRC Environm & Hlth, Sch Environm Sci & Engn, 27 Shanda South Rd, Jinan 250100, Shandong, Peoples R China.
来源：SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
关键词：Catalase; QDs; Spectroscopic studies; Static and dynamic quenching;; Activity inhibition
摘要：Quantum dots (QDs) are recognized as some of the most promising semiconductor nanocrystals in biomedical applications. However, the potential toxicity of QDs has aroused wide public concern. Catalase (CAT) is a common enzyme in animal and plant tissues. For the potential application of QDs in vivo, it is important to investigate the interaction of QDs with CAT. In this work, the effect of N-Acetyl-L-cysteine-Capped CdTe Quantum Dots with fluorescence emission peak at 612 nm (QDs-612) on CAT was investigated by fluorescence, synchronous fluorescence, fluorescence lifetime, ultraviolet-visible (UV-vis) absorption and circular dichroism (CD) techniques. Binding of QDs-612 to CAT caused static quenching of the fluorescence, the change of the secondary structure of CAT and the alteration of the microenvironment of tryptophan residues. The association constants K were determined to be K-288K = 7.98 x 10(5) L mol(-1) and K-298K = 7.21 x 10(5) L mol(-1). The interaction between QDs-612 and CAT was spontaneous with 1:1 stoichiometry approximately. The CAT activity was also inhibited for the bound QDs-612. This work provides direct evidence about enzyme toxicity of QDs-612 to CAT in vitro and establishes a new strategy to investigate the interaction between enzyme and QDs at a molecular level, which is helpful for clarifying the bioactivities of QDs in vivo. (C) 2014 Elsevier B.V. All rights reserved.