Site-Directed Mutagenesis of Two Cysteines (155, 202) in Catechol 1,2-dioxygenase $I_1$ of Acinetobacter lwoffii K24

Catechol 1,2-dioxygenase () is the first enzyme of the -ketoadipate pathway in Acinetobacter lowffii K24. has two cysteines (155, 202) and its enzyme activity is inhibited by the cysteine inhibitor, . Two mutants, C155V and C202V, were obtained by site-directed mutagenesis. The two mutants were overexpressed and the mutated amino acid residues (CysVal) were characterized by peptide mapping and amino acid sequencing. Interestingly, C155V was inhibited by , whereas C202V was not inhibited. This suggests that is the sole inhibition site by and is close to the active site of the enzyme. However, the results of the biochemical assay of mutated suggest that the two cysteines are not directly involved in the activity of the catechol 1,2-dioxygenase of .