Amphitrite ornata is a mudflat dwelling terebellid polychaetae marine that cohabitates with other organisms that release into the environment halogenated compounds as a defense mechanism. In a unique detoxification mechanism, A. ornata employs its hemoglobin, dehaloperoxidase (DHP), to degrade these toxic compounds and survive harsh conditions. Beyond oxygen transport, DHP possesses four oxidative functions: peroxidase, peroxygenase, oxidase and oxygenase. These functions enable DHP’s reactivity with diverse classes of organic substrates, including bromophenols, haloindoles, nitrophenols, bromopyrroles, o-guaiacols and cresols. Inspired by the substrate scope of DHP, we hypothesized that non-halogenated para-substituted phenols would also react with DHP, including 4-hydroxybenzaldehyde, 4-acetylphenol, 4-hydroxybenzoic acid, methylparaben, and ethylparaben. Utilizing chromatographic (HPLC) and spectroscopic (UV-visible and stopped-flow UV-visible) methods, substrate/DHP binding affinities and reactivities were assessed. Preliminary results (pH 7) indicate substrate reactivity ordered as: methylparaben, ethylparaben, 4-hydroxybenzaldehyde, while 4-hydroxybenzoaic acid and 4-acetylphenol were observed as unreactive. However, studies employing varying pH (± 0.5 units of substrate pKa) altered substrate reactivity: 4-hydroxybenzaldehyde (59.4±0.2%), ethylparaben (23.1±1.3%), 4-acetylphenol (14.7±4.1%), 4-hydroxybenzoic acid (5.8±1.6%), and methylparaben (2.1±1.7%). Substrates were optimized at pH 8, except 4-hydroxybenzoic acid, which was optimized at pH 5. These results suggest correlation between substituent group electron density and reactivity such that protonated forms of acid/base potential substrates show increased reactivity with DHP. Without a phenolic hydroxy group (methylbenzoate), no reactivity was observed. It is hypothesized that DHP is more reactive with para-substituted phenols with more electron density focused around the benzene ring when at pH values near the pKa values of the p-phenols.

Reactivity studies employing the multifunctional globin dehaloperoxidase on the oxidation of para-substituted phenols

Macromolecular Chemistry: The Second Century

[Author Benefits](https://scimeetings.acs.org/?utm_source=pubs_content_marketing&utm_medium=website&utm_campaign=0320_MCF_NPI_Launch_Spring_Homepage&ref=pubs_content_marketing)

[How to use SciMeetings](https://storage.googleapis.com/dl.morressier.com/acs/SciMeetings-ACSSpring2020-HowToGuide_M3020-Final.pdf)

[Frequently Asked Questions](https://storage.googleapis.com/dl.morressier.com/acs/SciMtng_ACSNMSp2020_FAQ_M3120_Final.pdf)

ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.