Authors: Jing Ma ZhiSheng Xu Feng Wang AiSheng Xiong
Publish Date: 2015/12/01
Volume: 34, Issue: 6, Pages: 444-452
Abstract
Laccases which belong to the blue copper oxidase enzyme family oxidize many organic and inorganic compounds The laccaseencoding genes DcLac1 and DcLac2 were isolated from the economically important tuberous root carrot and their proteins were successfully expressed and purified using the Escherichia coli expression system BL21DE3 DcLac1 and DcLac2 had molecular masses of approximately 64 and 619 kDa respectively With 22′azinobis3ethylbenzthiazoline6sulfonate acid as the substrate DcLac1 and DcLac2 had K m values of 39043 and 1255 mM respectively and V max values of 540832 and 817996 μM mg−1 min−1 respectively Moreover DcLac1 and DcLac2 had optimal pH values of 28 and 26 respectively and optimal temperatures of 45 and 40 °C respectively The activities of the two enzymes were promoted by Ca2+ Mg2+ Cu2+ and Na+ but inhibited by Fe2+ Zn2+ Mn2+ K+ SDS and EDTA Expression profiles showed that the two DcLac genes had almost identical responses to high and low temperature stresses but different responses to salt drought and metal stresses This study provided insights into the characteristics and tolerance response mechanisms of laccase in carrot
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