Dataset Information

Hematin and Cu^II control generations of hydroperoxyl and superoxide radicals to activate galactose oxidase for 5-hydroxymethylfurfural conversion.

ABSTRACT: We present a significant finding that Cu(II) ions can activate hematin (Hem) to generate more HOO⋅ and O₂^⋅- radicals from the decomposition of H₂O₂. Galactose oxidase (GO) and hematin have been simultaneously immobilized by coordinating to Cu(II) ions (GO&Hem@Cu(II)). The radicals HOO⋅ and O₂^⋅- and dioxygen O₂ can be in situ generated from the byproduct H₂O₂ by the Cu(II)-activated hematin. Ample experimental evidence supports the discovery that the immobilized GO is reactivated by the in situ generated HOO⋅ and O₂^⋅-. For the conversion of 100 mM 5-hydroxymethylfurfural (HMF) in water, GO&Hem@Cu(II) (0.8 mg/mL GO encapsulated) has achieved a 99.5% conversion within 180 min. In contrast, 0.8 mg/mL free GO M_3-5 variant (ACS Catalysis 2018, 8, 4025) has achieved an HMF conversion of 17.3%. For the conversion of HMF (1,000 mM) by GO&Hem@Cu(II) (4 mg/mL GO encapsulated), the HMF conversion is 98.8% after 8 h reaction.

SUBMITTER: Chen Y

PROVIDER: S-EPMC10711400 | biostudies-literature | 2023 Dec

REPOSITORIES: biostudies-literature

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Hematin and CuII control generations of hydroperoxyl and superoxide radicals to activate galactose oxidase for 5-hydroxymethylfurfural conversion.

Chen Yao Y Zou Jinxin J Ji Peijun P Feng Wei W

iScience 20231117 12

We present a significant finding that Cu(II) ions can activate hematin (Hem) to generate more HOO⋅ and O2⋅- radicals from the decomposition of H2O2. Galactose oxidase (GO) and hematin have been simultaneously immobilized by coordinating to Cu(II) ions (GO&Hem@Cu(II)). The radicals HOO⋅ and O2⋅- and dioxygen O2 can be in situ generated from the byproduct H2O2 by the Cu(II)-activated hematin. ...[more]

PMID: 38089572

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Project description:The unique ability of nitrone spin traps to detect and characterize transient free radicals by electron paramagnetic resonance (EPR) spectroscopy has fueled the development of new spin traps with improved properties. Among a variety of free radicals in chemical and biological systems, superoxide radical anion (O(2)(•-)) plays a critical role as a precursor to other more oxidizing species such as hydroxyl radical (HO(•)), peroxynitrite (ONOO(-)), and hypochlorous acid (HOCl), and therefore the direct detection of O(2)(•-) is important. To overcome the limitations of conventional cyclic nitrones, that is, poor reactivity with O(2)(•-), instability of the O(2)(•-) adduct, and poor cellular target specificity, synthesis of disubstituted nitrones has become attractive. Disubstituted nitrones offer advantages over the monosubstituted ones because they allow bifunctionalization of spin traps, therefore accommodating all the desired spin trap properties in one molecular design. However, because of the high number of possible disubstituted analogues as candidate, a systematic computational study is needed to find leads for the optimal spin trap design for biconjugation. In this paper, calculation of the energetics of O(2)(•-) and HO(2)(•) adduct formation from various disubstituted nitrones at PCM/B3LYP/6-31+G(d,p)//B3LYP/6-31G(d) level of theory was performed to determine the most favorable disubstituted nitrones for this reaction. In addition, our results provided general trends of radical reactivity that is dependent upon but not exclusive to the charge densities of nitronyl-C, the position of substituents including stereoselectivities, and the presence of intramolecular H-bonding interaction. Unusually high exoergic ΔG(298K,aq)'s for O(2)(•-) and HO(2)(•) adduct formation were predicted for (3S,5S)-5-methyl-3,5-bis(methylcarbamoyl)-1-pyrroline N-oxide (11-cis) and (4S,5S)-5-dimethoxyphosphoryl-5-methyl-4-ethoxycarbonyl-1-pyrroline N-oxide (29-trans) with ΔG(298K,aq) = -3.3 and -9.4 kcal/mol, respectively, which are the most exoergic ΔG(298K,aq) observed thus far for any nitrone at the level of theory employed in this study.

Dataset Information

Hematin and Cu^II control generations of hydroperoxyl and superoxide radicals to activate galactose oxidase for 5-hydroxymethylfurfural conversion.

Publications

Hematin and Cu<sup>II</sup> control generations of hydroperoxyl and superoxide radicals to activate galactose oxidase for 5-hydroxymethylfurfural conversion.

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