In this study, the recombinant catalytic subunit of AHAS from H. influenza (Hin-AHAS) was expressed in Escherichia coli. The purified Hin-AHAS protein exhibited a molecular weight of approximately 63 kDa on SDS-PAGE gel. The apparent Vmax and Km values of the purified Hin-AHAS were determined to be U/mg protein and mM pyruvate, respectively. | TAP CHI SINH Purification HOC and 2016, characterization 38(3): 367-373 DOI: PURIFICATION AND CHARACTERIZATION OF RECOMBINANT ACETOHYDROXYACID SYNTHASE FROM Haemophilus influenzae Le Thuy Linh1, Vu Tuan Nam2, Le Tien Dung2* 1 University of Science and Technology of Hanoi, VAST, Vietnam International Laboratory for Cassava Molecular Breeding, Agricultural Genetics Institute, Vietnam Academy of Agricultural Science, Vietnam 2 ABSTRACT: Acetohydroxyacid synthase (AHAS) presents only in plants and microorganisms. The enzyme catalyzes the first common step in the biosynthesis of branch chain amino acids (BCAAs), including isoleucine, leucine and valine. AHAS is also a potential target for controlling Haemophilus influenzae. In this study, the recombinant catalytic subunit of AHAS from H. influenza (Hin-AHAS) was expressed in Escherichia coli. The purified Hin-AHAS protein exhibited a molecular weight of approximately 63 kDa on SDS-PAGE gel. The apparent Vmax and Km values of the purified Hin-AHAS were determined to be U/mg protein and mM pyruvate, respectively. Two inhibitors of plant AHAS, namely ethoxysulfuron (ETS) and pyrazosulfuron ethyl, were shown to inhibit Hin-AHAS in a non-competitive manner with the IC50 values of µM and µM, respectively. This result showed that the purified enzyme can be used for screening of inhibitors against Hin-AHAS. Keywords: Haemophilus influenzae, acetohydroxyacid synthase, enzymatic activity, inhibitor, purification. Citation: Le Thuy Linh, Vu Tuan Nam, Le Tien Dung, 2016. Purification and characterization of recombinant acetohydroxyacid synthase from Heamophilus influenzae. Tap chi Sinh hoc, 38(3): 367-373. DOI: . *Corresponding author: research@. INTRODUCTION Haemophilus influenzae is a Gram-negative, coccobacillary, facultatively anaerobic bacterium which causes a variety of infections in both children and adults, ranging .
