Peroxidase-catalyzed polymerization and depolymerization of coal in organic solvents
Peroxidases from horseradish roots (HRP) and soybean hulls (SBP) catalyze the efficient polymerization of a 4-kDa dimethylformamide (DMF)-soluble fraction of Mequininza (Spanish) lignite in 50% (v/v) DMF with an aqueous component consisting of acetate buffer, pH 5.0. Under these conditions, HRP and SBP catalyze the oxidation of free phenolic moieties in the coal matrix, thereby leading to oxidative polymerization of the low-molecular-weight coal polymers. The high fraction of nonphenolic aromatic moieties in coal inspired us to examine conditions whereby such coal components could also become oxidized. Oxidation of nonphenolic aromatic compounds was attempted using veratryl alcohol as a model substrate. SBP catalyzed the facile oxidation of veratryl alcohol at pH <3.HRP, however, was unable to elicit veratryl alcohol oxidation. The potential for SBP to catalyze interunit bond cleavage on complex polymeric substrates was examined using l-(3,4-dimethoxyphenyl)-2-(phenoxy)propan-1,3-diol (1) as a substrate. SBP catalyzed the Cα-Cβ and β-ether bond cleavage of this compound, suggesting that similar reactions on coal, itself, could lead to depolymerization. Depolymerization of a >50 Da coal fraction was achieved using SBP in 50% (v/v) DMF with an aqueous component adjusted to pH 2.2. Approximately 15% of the initial high-molecular-weight lignite fraction was depolymerized to polymers 4 Da in size. Hence, SBP is capable of catalyzing the depolymerization of coal in organic solvents, and this may have important ramifications in the generation of liquid fuels from coals.
Index entriesPeroxidase from soybean hulls coal depolymerization enzymatic oxidation of veratryl alcohol
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- 1.Stock, L. M. (1985), inChemistry of Coal Conversion, Schlosberg, R. H. ed., Plenum, New York, pp. 253–316.Google Scholar
- 2.Speight, J. G. (1983),The Chemistry and Technology of Coal, Marcel Dekker, New York, pp. 215–240.Google Scholar
- 3.Cohen, N. S. and Gabriele, P. D. (1982),Appl. Environ. Microbiol. 44, 23–27.Google Scholar
- 5.Pyne, J. W., Jr., Stewart, D. L., Fredrickson, J., and Wilson, B. W. (1987),Appl. Environ. Microbiol. 53, 2844–2848.Google Scholar
- 6.Ward, B. (1985),System. Appl Microbiol. 6, 236–238.Google Scholar
- 7.Runnion, K. and Combie, J. D. (1990),Appl. Biochem. Biotechnol. 24/25, 817–829.Google Scholar
- 10.Scott, C. D. and Lewis, S. N. (1988),Appl. Biochem. Biotechnol. 18, 403–412.Google Scholar
- 13.Klyachko, N. L. and Klibanov, A. M. (1992),Appl. Biochem. Biotechnol. 37, 53–68.Google Scholar
- 14.Scott, C. D., Woodward, C. A., Thompson, J. E., and Blankinship, S. L. (1990),Appl. Biochem. Biotechnol. 24/25, 799–815.Google Scholar
- 17.Hayatsu, R., Winans, R. E., McBeth, R. L., Scott, R. G., Moore, L. P., and Studier, M. H. (1981), inCoal Structure, vol. 192 ofAdvances in Chemistry Series, Gorbaty, M. L. and Ouchi, K., eds., American Chemical Society, Washington, DC, pp. 133–149.Google Scholar
- 22.Waters, W. A. and Littler, J. S. (1965), inOxidation in Organic Chemistry, vol. 5a, Wiberg, K. B., ed., Academic, New York, pp. 185–241.Google Scholar
- 24.McEldoon, J. P. and Dordick, J. S. (1991),J. Biol. Chem. 266, 14288–14293.Google Scholar