Catalytic Activities of Lignin-Degrading Enzymes From the White-Rot Fungus Phlebia Radiata: Lignin Model Compound Studies

Hatakka, A.; Lundell, Taina; Mohammadi, Oili; Tervilä-Wilo, Asta

doi:10.1016/b978-0-409-90192-4.50043-1

Cited by 3 publications

(5 citation statements)

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“…Guaiacol has been detected as a product from this dimer after oxidation by L3 [48] and by P. chrysosporium Lip H8 [25]. Furthermore, LIP oxidises guaiacol in the presence of H,O, [64] apparently to phenoxy radicals which is a one-electron oxidation.…”

Section: Degradation Mechanism Of the P-0-4 Dimermentioning

confidence: 97%

“…The second part of the dimer, after Ca-Cp cleavage, is left as a Cp cation which would easily be attacked by a nucleophile, such as HzO, and undergo further fragmentation to guaiacol (2-methoxyphenol) and glycolaldehyde [3]. Guaiacol has been detected as a product from this dimer after oxidation by L3 [48] and by P. chrysosporium Lip H8 [25]. Furthermore, LIP oxidises guaiacol in the presence of H,O, [64] apparently to phenoxy radicals which is a one-electron oxidation.…”

Section: Degradation Mechanism Of the P-0-4 Dimermentioning

confidence: 99%

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Lignin peroxidase L3 from Phlebia rediata

Lundell

Wever

Floris

et al. 1993

European Journal of Biochemistry

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The catalytic cycle of lignin peroxidase (Lip, ligninase) isozyme L3 from the white-rot fungus Phlebia radiata was investigated using stopped-flow techniques. Veratryl (3,4-dimethoxybenzyl) alcohol and a lignin model compound, non-phenolic a-0-4 dimer 1 -(3,4-dimethoxyphenyl)-2-(2-methoxyphenoxy)propane-1,3-diol, were used as electron donors. This is the first report on the detailed kinetic analysis of a Lip-catalysed Ca-CB bond cleavage of the dimer, representing the major depolymerisation reaction in the lignin polymer. The native enzyme showed a typical heme peroxidase absorbance spectrum with a Soret maximum at 407 nm. Following the reaction with H,Oz, the Soret band decreased in absorbance, shifted to 403 nm and then to 421 nm, demonstrating the formation of compound I followed by the formation of compound 11, respectively. Similar results have been reported for the Lip from Phunerochaete chrysosporium upon reaction with H,O,. However, compound I of L3 was more stable in the absence of additional electron donors. Thesecond-order rate constant of compound I formation by H,O, was determined to be 6 X IOI M-' s-' and was the same at pH 3.0 and 6.0. Compound I was rapidly reduced to compound Il and further to native enzyme when either veratryl alcohol or the p-0-4 dimer was supplied as electron donor and in both cases veratraldehyde appeared as the major product. At pH 6.0, the second-order rate constant for compound I1 formation was similar with either veratryl alcohol or the p-0-4 dimer (6.7 X lo3 and 6.5 X 103 M-' s-', respectively). At pH 3.0 formation of compound I1 with either reductant proceeded so rapidly that determination of the respective rate constants was not possible. The results point to identical catalytic cycles of L3 with veratryl alcohol or the p-0-4 dimer involving both compounds I and I1 as intermediates and participation of the same veratryl alcohol radical as the most appropriate reductant for compound 11. Chemical evidence of such a radical, formed after the initial Lip-catalysed one-electron oxidation of p-0-4 dimeric lignin models, is presented in a separate article [Lundell, T., Schoemaker, H., Hatakka, A. & Brunow, G. (1993) Holgorschung, in the press]. The catalytic redox-cycle and the oxidation mechanism presented here reconcile seemingly contradictory results obtained in previous studies on Lip kinetics during the last decade.Lignin peroxidase (Lip, ligninase) is an extracellular lignin-degrading enzyme, first discovered in the white-rot fungus Phanerochaete chrysosporium Burds. [I, 21. The enzyme is a glycoprotein that typically has molecular mass of

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Section: Degradation Mechanism Of the P-0-4 Dimermentioning

confidence: 97%

Section: Degradation Mechanism Of the P-0-4 Dimermentioning

confidence: 99%

Lignin peroxidase L3 from Phlebia rediata

Lundell

Wever

Floris

et al. 1993

European Journal of Biochemistry

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“…These enzymes may contribute to the further oxidation of V. The absolute level of lignin peroxidase activity is difficult to assess in growing cultures since the accumulation of V (from I) stimulates the production of lignin peroxidases both in Phanerochaete chrysosporium (Faison and Kirk 1985;Leisola et al 1985) and in Phlebia radiata (Hatakka et al 1986(Hatakka et al , 1987Niku-Paavola et al 1990), and all the dimeric models I, II and III stimulate lignin peroxidase production in P. radiata (Hatakka et al !987). Moreover, in reaction mixtures containing the lignin peroxidase of P. radiata, both dimeric model compound and V, oxidation of V to IV is retarded Hatakka et al 1990 (Rogalski et al 1990, unpublished results). The ring-cleavage products from ¥ were rarely found in our experiments with whole cultures.…”

Section: Discussionmentioning

confidence: 99%

“…The subsequent metabolism of veratryl compounds was relatively efficient in Phlebia radiata. Degradation patterns of non-phenolic t-O-4 dimers and other types of lignin model compounds using purified lignin peroxidases from P. radiata have been studied preliminarily Hatakka et al 1990) and studies using polymer-bound t-O-4 models are under way in our laboratory (Hatakka et al 1991).…”

Section: Discussionmentioning

confidence: 99%

“…The degradation and transformation of dimeric lignin model compounds and monomeric aromatic compounds Hatakka et al 1990) and polymer-bound dimeric models (Hatakka et al 1991) by purified lignin peroxidase of P. radiata has been reported and the stimulating effect of dimeric lignin model compounds on the production of ligninmodifying enzymes has been described earlier (Hatakka et al 1987). Here, we report on the metabolism of three non-phenolic dimeric r-O-4 lignin model compounds by whole cultures of P. radiata, and compare the results with those from Phanerochaete chrysosporium.…”

Section: Introductionmentioning

confidence: 99%

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Metabolism of non-phenolic ?-O-4 lignin model compounds by the white-rot fungus Phlebia radiata

Hatakka

Lundell

Tervilä-Wilo

et al. 1991

Appl Microbiol Biotechnol

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The degradation of three non-phenolic fl-Oo 4 diarylpropane lignin model compounds was studied in cultures of the white-rot fungus Phlebia radiata. The degradation pattern of the model compound 1-(3,4-dimethoxyphenyl)-2-(2-methoxyphenoxy)propane-l,3-diol (I) was also compared with that of Phanerochaete chrysosporium under conditions where both fungi were cultivated without agitation in an oxygen atmosphere. Compound I was readily degraded by both fungi, and qualitatively the degradation patterns were quite similar. The product, after Ca-C a bond cleavage, was veratraldehyde (IV) which was almost stoichiometrically reduced to veratryi alcohol (V). However, large amounts of V were detected only in P. chrysosporiurn cultures. Experiments with the model compound 1-(4-ethoxy-3-methoxyphenyl)-2-(2-methoxyphenoxy)propane-l,3-diol (II) showed that in the presence of II, the total amount of veratryl compounds accounted for [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33].LM in standing cultures of Phlebia radiata. The model compound 1-(3,4-dimethoxyphenyl)-2-(4-methoxyphenoxy) propane-l,3-diol (III) was more readily degraded than I and II. The results indicated that, in P. radiata cultures, the acting enzymes were lignin peroxidases and IV reducing enzyme, while laccase was less important.

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