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Peroxygenase and oxidase activities of dehaloperoxidase‐hemoglobin from Amphitrite ornata (580.1)
Author(s) -
Ghiladi Reza,
McCombs Nikolette
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.580.1
Subject(s) - chemistry , substrate (aquarium) , ferric , stereochemistry , hemoglobin , enzyme , globin , organic chemistry , biology , ecology
The marine globin dehaloperoxidase‐hemoglobin (DHP) from Amphitrite ornata was found to catalyze the H 2 O 2 ‐dependent oxidation of monohaloindoles, a previously unreported class of substrate for DHP. Using 5‐Br‐indole as a representative substrate, the major monooxygenated products were found to be 5‐Br‐2‐oxindole and 5‐Br‐3‐oxindolenine. Isotope labeling studies confirmed that the oxygen atom incorporated was derived exclusively from H 2 O 2 , indicative of a previously unreported peroxygenase activity for DHP. Peroxygenase activity could be initiated from either the ferric or oxyferrous states with equivalent substrate conversion and product distribution. It was found that 5‐Br‐3‐oxindole, a precursor of the product 5‐Br‐3‐oxindolenine, readily reduced the ferric enzyme to the oxyferrous state, demonstrating an unusual product‐driven reduction of the enzyme. As such, DHP returns to the globin‐active oxyferrous form after peroxygenase activity ceases. Reactivity with 5‐Br‐3‐oxindole in the absence of H 2 O 2 also yielded 5,5’‐Br 2 ‐indigo above the expected reaction stoichiometry under aerobic conditions, and O 2 ‐concentration studies demonstrated dioxygen consumption. Non‐enzymatic and anaerobic controls both confirmed the requirements for DHP and molecular oxygen in the catalytic generation of 5,5’‐Br 2 ‐indigo, and together suggest a novel oxidase activity for DHP. Grant Funding Source : Supported by the National Science Foundation CHE‐1150709