Roles of active site residues in LodA, a cysteine tryptophylquinone dependent ε-lysine oxidase.

摘要: Site-directed mutagenesis identified residues in the substrate channel of LodA that play multiple roles regulating Km values substrates, kcat and extent biosynthesis protein-derived cysteine tryptophylquinone (CTQ) cofactor. Mutations Cys448 increase for lysine O2, with larger effect on Klysine. Tyr211 resides within a mobile loop is seen crystal structure to form hydrogen bond Lys530 appears stabilize its position channel. Y211F had reduced levels CTQ but near normal kcat. K530A K530R variants exhibited diminished significantly increased The Y211F, mutations each caused large increases O2. These effects suggest when these are hydrogen-bonded they may gate controls entry exit substrates products from active site. Y211A Y211E highest level no activity. results highlight different evolutionary factors must be considered enzymes which possess cofactors, catalytic cofactor generated by posttranslational modifications.