Full Length Research Paper

Purification and biochemical characterization of a novel glutathione S-transferase of the silkworm, Bombyx mori

Cheng Xiang Hou^1,2, Zhi Qiang Fu³, Byung Rae Jin⁴ and Zhong Zheng Gui^1,2*

¹Jiangsu University of Science and Technology, Zhenjiang 212018, China.

²Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang 212018, China.

³Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai 200232, China.

⁴College of Natural Resources and Life Science, Dong-A University, Pusan 604714, Korea.

*Corresponding author. E-mail: srizzgui@hotmail.com. Tel: 86-511-8561-6716.

Accepted 10 January, 2008

A novel glutathione S-transferase has been purified from Bombyx mori larvae using affinity chromatography on a glutathione agarose column. The purified enzyme appeared as a single band on SDS-PAGE and had a M_r of 28 kDa. Steady state kinetic assays of the enzyme were conducted with 1-chloro-2,4-dinitrobenzene as a substrate. The K_m, V_max, K_cat and K_cat/K_m for the purified BmGST were 0.494 mM, 72.07 mmol/min/mg, 65.43 s^-1 and 132.45 mM^-1·s^-1, respectively. The enzyme had a maximum activity at approximately pH 7.1 and 25ºC. BmGST indicated lower inhibitory rate by some inhibitors (albendazol, praziquantel, bile acid and NaCl), suggesting that this novel BmGST could differ structurally or functionally from other animal GSTs.

Key words: Purification, characterization, glutathione S-transferase, Bombyx mori.