title: Enzymatic activity analysis and catalytic essential residues identification of Brucella abortus malate dehydrogenase.
abstract: Malate dehydrogenase (MDH) plays important metabolic roles in bacteria. In this study, the recombinant MDH protein (His-MDH) of Brucella abortus was purified and its ability to catalyze the conversion of oxaloacetate (OAA) to L-malate (hereon referred to as MDH activity) was analyzed. Michaelis Constant (Km) and Maximum Reaction Velocity (Vmax) of the reaction were determined to be 6.45 × 10(-3) M and 0.87 mM L(-1)min(-1), respectively. In vitro studies showed that His-MDH exhibited maximal MDH activity in pH 6.0 reaction buffer at 40°C. The enzymatic activity was 100%, 60%, and 40% inhibited by Cu(2+), Zn(2+), and Pb(2+), respectively. In addition, six amino acids in the MDH were mutated to investigate their roles in the enzymatic activity. The results showed that the substitutions of amino acids Arg 89, Asp 149, Arg 152, His 176, or Thr 231 almost abolished the activity of His-MDH. The present study will help to understand MDH's roles in B. abortus metabolism.
authors.affiliation: Shanghai Veterinary Research Institute, The Chinese Academy of Agricultural Sciences (CAAS), 518 Ziyue Road, Shanghai 200241, China.
authors.forename: Xiangan
authors.initials: X
authors.lastname: Han
authors.affiliation: Shanghai Veterinary Research Institute, The Chinese Academy of Agricultural Sciences (CAAS), 518 Ziyue Road, Shanghai 200241, China.
authors.forename: Yongliang
authors.initials: Y
authors.lastname: Tong
authors.affiliation: Shanghai Veterinary Research Institute, The Chinese Academy of Agricultural Sciences (CAAS), 518 Ziyue Road, Shanghai 200241, China.
authors.forename: Mingxing
authors.initials: M
authors.lastname: Tian
authors.affiliation: Shanghai Veterinary Research Institute, The Chinese Academy of Agricultural Sciences (CAAS), 518 Ziyue Road, Shanghai 200241, China.
authors.forename: Yuxi
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Shanghai Veterinary Research Institute, The Chinese Academy of Agricultural Sciences (CAAS), 518 Ziyue Road, Shanghai 200241, China.
authors.forename: Xiaoqing
authors.initials: X
authors.lastname: Sun
authors.affiliation: Shanghai Veterinary Research Institute, The Chinese Academy of Agricultural Sciences (CAAS), 518 Ziyue Road, Shanghai 200241, China.
authors.forename: Shaohui
authors.initials: S
authors.lastname: Wang
authors.affiliation: Shanghai Veterinary Research Institute, The Chinese Academy of Agricultural Sciences (CAAS), 518 Ziyue Road, Shanghai 200241, China.
authors.forename: Xusheng
authors.initials: X
authors.lastname: Qiu
authors.affiliation: Shanghai Veterinary Research Institute, The Chinese Academy of Agricultural Sciences (CAAS), 518 Ziyue Road, Shanghai 200241, China.
authors.forename: Chan
authors.initials: C
authors.lastname: Ding
authors.affiliation: Shanghai Veterinary Research Institute, The Chinese Academy of Agricultural Sciences (CAAS), 518 Ziyue Road, Shanghai 200241, China.
authors.forename: Shengqing
authors.initials: S
authors.lastname: Yu
mesh_terms: D002003:Brucella abortus / Q000201:enzymology*; D006863:Hydrogen-Ion Concentration; D008291:Malate Dehydrogenase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D008291:Malate Dehydrogenase