Enzyme-substrate interaction and characterization of a 2,3-dihydroxybiphenyl 1,2-dioxygenase from Dyella ginsengisoli LA-4

A bphC gene (915 bp) encoding 2,3-dihydroxybiphenyl 1,2-dioxygenase (BphC) was amplified by PCR from Dyella ginsengisoli LA-4, which was heterologously expressed in Escherichia coli. The purified His-Tag BphC was able to catalyze the meta-cleavage reaction of the dihydroxylated aromatic rings. According to the specificity constant (K-cat/K-m) of BphC_LA-4, the specificity of BphC_LA-4 was determined in the following order: 2,3-dihydroxybiphenyl > 3-methylcatechol > catechol > 4-chlorocatechol > 4-methylcatechol. The experimental data were consistent with the prediction of enzyme-substrate complexes. The highest specific activity of BphC_LA-4 was 118.3 U mg(-1) for 2,3-dihydroxybiphenyl.