典型金属离子对漆酶催化降解溴代阻燃剂四溴双酚A的影响研究

Effect of metal ions on laccase-catalyzed degradation of tetrabromobisphenol A

研究了自然环境、垃圾渗滤液及工业废水中广泛存在的金属离子对真菌漆酶(Trametes versicolor)酶活性以及对漆酶催化降解典型溴代阻燃剂四溴双酚A(TBBPA)的影响.金属离子包括Na^+、K+、Zn^2+、Cd^2+、Cu^2+、Hg^2+、Fe^2+、Fe3+、Pb^2+、Al3+能抑制漆酶酶活性和降低TBBPA的降解转化率,抑制效应随着金属离子浓度的升高而增大;Ca^2+、Mg^2+、Mn^2+则对漆酶活性和TBBPA去除率均没有显著影响.金属离子的抑制作用主要是通过干扰漆酶的电子传递过程产生的.其中,Fe^2+和Hg^2+的抑制效应尤为明显,而二者的抑制机制不同,Fe^2+竞争消耗O2,Hg^2+则通过与漆酶结构中氨基酸络合,改变其构型从而抑制其活性.此外,通过加入介体物质2,2-联氮-二(3-乙基-苯并噻唑-6-磺酸)二铵盐(ABTS)、2,2,6,6-四甲基哌啶-氮-氧化物(TEMPO)等物质能够显著提高金属离子存在下漆酶对TBBPA的去除率.

In this study,the influences of different metal ions that present in natural water,industrial wastewater and landfill leachates on laccase(from Trametes versicolor)activity and laccase-catalyzed degradation of tetrabromobisphenol A(TBBPA)were examined.Metal ions including Na^+、K+、Zn^2+、Cd^2+、Cu^2+、Hg^2+、Fe^2+、Fe3+、Pb^2+、Al3+inhibited laccase activity and TBBPA degradation,and the inhibitions depend on metal ion species and concentrations.These metal ions affect laccase-catalyzed conversion of TBBPA through interrupting the electron transport system of laccase.However,because most metal ions inhibit the catalytic activity of laccase only at high concentration(e.g.,10 mmol·L^-1),they would not influence laccase performance in natural water or wastewater water matrix.In particular,Fe^2+and Hg^2+substantially reduced TBBPA removal even at lower concentration(e.g.,10μmol·L^-1).The inhibition of Fe^2+was attributed to oxygen consumption,while the inhibition of Hg^2+occurred by binding with amino acid residues on laccase.In addition,2,2′-azino-bis(3-ethylbenz-thiazoline-6-sulfonic acid)(ABTS)and 2,2,6,6-tetramethyl-1-piperidinyloxy free radical(TEMPO)as mediators were able to improve laccase-catalyzed degradation of TBBPA in the presence of metal ions,and TEMPO was identified as the most effective one.