甘薯（Ipomoea batatas [L.] Lam）脱氢抗坏血酸还原酶cDNA：表达、酶特性及动力学研究
Dehydroascorbate reductase cDNA from sweet potato (Ipomoea batatas [L.] Lam): expression, enzyme properties, and kinetic studies.
作者信息
Jiang Yu-Chi, Huang Chih-Yu, Wen Lisa, Lin Chi-Tsai
机构信息
Institute of Bioscience and Biotechnology and Center for Marine Bioscience and Biotechnology, National Taiwan Ocean University, Keelung 202, Taiwan.
出版信息
J Agric Food Chem. 2008 May 28;56(10):3623-7. doi: 10.1021/jf073511e. Epub 2008 Apr 30.
A cDNA encoding a putative dehydroascorbate reductase (DHAR) was cloned from sweet potato. The deduced protein showed a high level of sequence homology with DHARs from other plants (67 to approximately 81%). Functional sweet potato DHAR was overexpressed and purified. The purified enzyme showed an active monomeric form on a 12% native PAGE. The protein's half-life of deactivation at 50 degrees C was 10.1 min, and its thermal inactivation rate constant K(d) was 6.4 x 10(-2) min(-1). The enzyme was stable in a broad pH range from 6.0-11.0 and in the presence of 0.8 M imidazole. The K(m) values for DHA and GSH were 0.19 and 2.38 mM, respectively.
从甘薯中克隆出一个编码假定脱氢抗坏血酸还原酶（DHAR）的cDNA。推导的蛋白质与其他植物的DHAR显示出高度的序列同源性（67%至约81%）。功能性甘薯DHAR被过量表达并纯化。纯化后的酶在12%的非变性聚丙烯酰胺凝胶电泳上呈现出活性单体形式。该蛋白质在50℃下失活的半衰期为10.1分钟，其热失活速率常数K(d)为6.4×10⁻²分钟⁻¹。该酶在6.0 - 11.0的广泛pH范围内以及在0.8 M咪唑存在的情况下是稳定的。DHA和GSH的K(m)值分别为0.19和2.38 mM。
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