Enzymes that catalyze hydroxylation of unactivated carbons normally contain heme and nonheme iron cofactors. By contrast, how a pyridoxal phosphate (PLP)-dependent enzyme could catalyze such a hydroxylation was unknown. Here, we investigate RohP, a PLP-dependent enzyme that converts l-arginine to ( S)-4-hydroxy-2-ketoarginine ...
Enzymes that catalyze hydroxylation of unactivated carbons normally contain heme and nonheme iron cofactors. By contrast, how a pyridoxal phosphate (PLP)-dependent enzyme could catalyze such a hydroxylation was unknown. Here, we investigate RohP, a PLP-dependent enzyme that converts l-arginine to ( S)-4-hydroxy-2-ketoarginine. We determine that the RohP reaction consumes oxygen with stoichiometric release of H 2 O 2 . To understand this unusual chemistry, we obtain ∼1.5 Å resolution structures that capture intermediates along the catalytic cycle. Our data suggest that RohP carries out a four-electron oxidation and a stereospecific alkene hydration to give the ( S)-configured product. Together with our earlier studies on an O 2 , PLP-dependent l-arginine oxidase, our work suggests that there is a shared pathway leading to both oxidized and hydroxylated products from l-arginine.
Organizational Affiliation:
Institute of Pharmaceutical Biotechnology, School of Medicine , Zhejiang University , Hangzhou , China.
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