Mononuclear nonheme iron(II) and 2‐oxoglutarate (Fe/2OG)‐dependent oxygenases and halogenases are known to catalyze a diverse set of oxidative reactions, including hydroxylation, halogenation, epoxidation, and desaturation in primary metabolism and natural product maturation. However, their use in abiotic transformations has mainly been limited to C−H oxidation. Herein, we show that various enzymes of this family, when reconstituted with Fe(II) or Fe(III), can catalyze Mukaiyama hydration—a redox neutral transformation. Distinct from the native reactions of the Fe/2OG enzymes, wherein oxygen atom transfer (OAT) catalyzed by an iron‐oxo species is involved, this nonnative transformation proceeds through a hydrogen atom transfer (HAT) pathway in a 2OG‐independent manner. Additionally, in contrast to conventional inorganic catalysts, wherein a dinuclear iron species is responsible for HAT, the Fe/2OG enzymes exploit a mononuclear iron center to support this reaction. Collectively, our work demonstrates that Fe/2OG enzymes have utility in catalysis beyond the current scope of catalytic oxidation.
Iron(II) can catalyze the oxidation of luminol in seawater and this chemiluminescent reaction has been widely used for iron(II) determination. The method is vulnerable to interferences from other analytes that catalyze luminol oxidation. We have shown that addition of diethylenetriamine pentaacetic acid (DTPA) to a sample inhibits the reaction of iron(II) with luminol, while not affecting other substances that also catalyze luminol oxidation under our experimental conditions. DTPA‐treated samples can therefore be used as sample blanks, with the difference between an untreated seawater sample and a DTPA‐treated seawater sample related to the concentration of dissolved iron(II). The DTPA correction has been applied to measure diel variability of iron(II) due to photoreduction in a coastal environment, and to measure vertical distributions of iron(II) in the eastern tropical north Pacific oxygen deficient zone.
more » « less- NSF-PAR ID:
- 10076330
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Limnology and Oceanography: Methods
- Volume:
- 16
- Issue:
- 11
- ISSN:
- 1541-5856
- Page Range / eLocation ID:
- p. 750-759
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Mononuclear nonheme iron(II) and 2‐oxoglutarate (Fe/2OG)‐dependent oxygenases and halogenases are known to catalyze a diverse set of oxidative reactions, including hydroxylation, halogenation, epoxidation, and desaturation in primary metabolism and natural product maturation. However, their use in abiotic transformations has mainly been limited to C−H oxidation. Herein, we show that various enzymes of this family, when reconstituted with Fe(II) or Fe(III), can catalyze Mukaiyama hydration—a redox neutral transformation. Distinct from the native reactions of the Fe/2OG enzymes, wherein oxygen atom transfer (OAT) catalyzed by an iron‐oxo species is involved, this nonnative transformation proceeds through a hydrogen atom transfer (HAT) pathway in a 2OG‐independent manner. Additionally, in contrast to conventional inorganic catalysts, wherein a dinuclear iron species is responsible for HAT, the Fe/2OG enzymes exploit a mononuclear iron center to support this reaction. Collectively, our work demonstrates that Fe/2OG enzymes have utility in catalysis beyond the current scope of catalytic oxidation.
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