Peroxidase-catalyzed polymerization and depolymerization of coal in organic solvents

Blinkovsky, Alexander M.; McEldoon, James P.; Arnold, John M.; Dordick, Jonathan S.

doi:10.1007/bf02788549

Cited by 24 publications

(10 citation statements)

References 22 publications

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“…Recently, a peroxidase from soybean hulls (SBP) has been isolated and characterized (McEldoon et al, 1995; Blinkovsky et al, 1994). SBP is similar catalytically to lignin peroxidase (LiP) and can oxidize veratryl alcohol and other nonphenolic aromatics directly in the presence of H 2 O 2 (McEldoon et al, 1995).…”

Section: Introductionmentioning

confidence: 99%

Unusual Thermal Stability of Soybean Peroxidase

McEldoon

Dordick

1996

Biotechnology Progress

134

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Soybean peroxidase (SBP) has an extremely high melting temperature of 90.5°C at pH 8.0 in the presence of 1 mM CaCl 2 . The enzyme is substantially more thermostable than the peroxidases from horseradish (HRP) and Coprinus cinereus (CIP). SBP denaturation does not precisely fit the two-state denaturation model due to the formation of the apoenzyme upon initial melting. A pseudo-two-state denaturation can be assumed, however, and this gives rise to apparent kinetics for irreversible inactivation. The apparent kinetics indicate that irreversible deactivation is comprised primarily of enthalpic contributions, with ∆H q deact ) 22.4 kcal/mol and T∆S q deact ) 0.2 kcal/mol at 95°C. Heme transfer studies from the peroxidases to apomyoglobin indicate that SBP holds onto its heme much more tightly than does HRP, and this is consistent with a thermodynamically more stable enzyme.

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Section: Introductionmentioning

confidence: 99%

Unusual Thermal Stability of Soybean Peroxidase

McEldoon

Dordick

1996

Biotechnology Progress

134

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“…The short retention times required to achieve complete polymerization of phenolic compounds by peroxidases, assuming detoxification of the aqueous phase, make this an attractive methodology for treating recalcitrant toxic halogenated phenols. Various sources of enzymes have been examined for use in such a process, each offering advantages 6–8, 36, 37. Fungal LIP possesses a redox potential higher than any known peroxidase, and is consequently able to oxidize a wider range of substrates, including certain non‐phenolic aromatics.…”

Section: Discussionmentioning

confidence: 99%

“…Oxidation of phenols by horseradish peroxidase (HRP) has received particular attention, probably since this enzyme has been well characterized, is commercially available at a low cost relative to other enzymes, and is able to function under a wide range of pH and temperature 6. A recently discovered peroxidase from soybean hulls (SBP) has also been considered for wastewater treatment 7, 8. SBP has a very high thermostability, similar to that typically found in thermophilic microbial enzymes9 and is stable over a broad pH range 10.…”

Section: Introductionmentioning

confidence: 99%

Lignin peroxidase‐catalyzed polymerization and detoxification of toxic halogenated phenols

Ward

Hadar

Dosoretz

2003

J of Chemical Tech & Biotech

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Halogenated phenols and bisphenols are recognized as being recalcitrant in conventional biological treatments. The current research evaluated lignin peroxidase-catalyzed oxidation and polymerization as a potential alternative for their detoxification. Gel permeation-HPLC analysis demonstrated the formation of dimers, trimers and tetramers upon oxidation of the target substrates. Polymerization was accompanied by effective detoxification of the aqueous phase during oxidation of 2,4-dibromophenol, the extent of which correlated with the extent of oxidation and polymerization. Steady state kinetic measurements at a saturating concentration of H 2 O 2 revealed high K m values (270-1100 µmol dm −3 ) for the target substrates, reflecting the strong electron-withdrawing properties of halogen substituents, which increase the oxidation potential of the phenols, resulting in thermodynamically less favorable reactions. However, k cat values were not dissimilar from non-halogenated phenols and the rapid oxidation and polymerization suggests that low retention times could be expected in a continuous process for their treatment, in contrast to conventional biological methods. The operational stability of lignin peroxidase was significantly improved by inclusion of redox mediators, which resulted in enhanced oxidation and more rapid reaction rates. However, due to their inherent toxicity, the use of redox mediators impeded toxicity assays. The findings highlight the potential of lignin peroxidase as a possible alternative for the high-rate treatment of industrial wastewater when conventional methods are ineffective.

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“…In addition to fungal peroxidases, two plant peroxidases, soybean hull peroxidase (SBP) and horseradish peroxidase (HRP), have been studied for their ability to modify lignite (BLINKOVSKY et al, 1994). SBP catalyzed the partial depolymerization of a high-molecular weight coal fraction obtained from a Spanish lignite in 50% (v/v) DMF with an aqueous component consisting of acetate buffer adjusted to pH 2.2.…”

Section: Peroxidasesmentioning

confidence: 99%