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Enzymatic Properties of a Recombinant Phospholipid Hydroperoxide Glutathione Peroxidase from Momordica charantia and Its Complementation Function in Yeast

Chun-Juan Dong, Xiao-Dong Yang, and Jin-Yuan Liu*

Laboratory of Molecular Biology and MOE Laboratory of Protein Science, Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing 100084, China; fax: (86) 10-6277-2243; E-mail: liujy@mail.tsinghua.edu.cn

* To whom correspondence should be addressed.

Received September 27, 2008; Revision received December 17, 2008
The entire encoding region for Momordica charantia phospholipid hydroperoxide glutathione peroxidase (McPHGPx) was cloned into pET-28a(+) vector and expressed in Escherichia coli BL21(DE3). The purified recombinant McPHGPx displayed GSH-dependent peroxidase activity towards phospholipid hydroperoxide, H2O2, and tert-butyl hydroperoxide and had the highest affinity with and catalytic efficiency for phospholipid hydroperoxide. The optimum temperature of the enzyme activity ranged from 40 to 50°C, thus it is a thermostable enzyme compared to other PHGPx enzymes. Furthermore, McPHGPx expression in Saccharomyces cerevisiae PHGPx-deletion mutant rescued the susceptibilities to the oxidation-sensitive polyunsaturated fatty acid (linolenic acid), indicating its PHGPx complementation function in yeast. These results have well documented that McPHGPx functions as a PHGPx in vitro and in vivo and will be beneficial for further functional studies on plant PHGPx enzymes.
KEY WORDS: phospholipid hydroperoxide glutathione peroxidase, Momordica charantia, enzymatic properties, functional complementation, antioxidant enzyme

DOI: 10.1134/S0006297909050046