Study on the residual lignin in <i>Eucalyptus globulus</i> sulphite pulp

Magina, Sandra; Marques, A.; Evtuguin, Dmitry V.

doi:10.1515/hf-2014-0218

Cited by 20 publications

(14 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Prior to Fourier transformation, the data matrices were zero-filled to 1024 points in the 13 C dimension. Signals were assigned by literature comparison ( 23 – 28 ). In the aromatic region of the spectrum, the lignin C 2 -H 2 , C 5 -H 5 , and C 6 -H 6 correlation signals were integrated to estimate the amount of lignins and the syringyl-to-guaiacyl ratio.…”

Section: Methodsmentioning

confidence: 99%

Demonstration of Lignin-to-Peroxidase Direct Electron Transfer

Sáez-Jiménez

Baratto

Pogni

et al. 2015

Journal of Biological Chemistry

View full text Add to dashboard Cite

Background: Ligninolytic peroxidases are often studied using simple model substrates.Results: Reaction of versatile peroxidase with the lignin polymer is shown by a combination of directed mutagenesis, chromatographic, and spectroscopic techniques.Conclusion: The main reaction implies direct electron transfer to a surface tryptophanyl radical responsible for lignin oxidation.Significance: This is the first time that this central mechanistic aspect is shown for a ligninolytic peroxidase.

show abstract

Section: Methodsmentioning

confidence: 99%

Demonstration of Lignin-to-Peroxidase Direct Electron Transfer

Sáez-Jiménez

Baratto

Pogni

et al. 2015

Journal of Biological Chemistry

View full text Add to dashboard Cite

show abstract

“…HSQC spectra processing used typical matched Gaussian apodization in the 1 H dimension and squared cosine-bell apodization in the 13 C dimension. Signals were assigned by comparison with the literature [ 26 , 47 , 48 , 49 , 50 , 51 , 52 ].…”

Section: Methodsmentioning

confidence: 99%

Agaricales Mushroom Lignin Peroxidase: From Structure–Function to Degradative Capabilities

et al. 2021

View full text Add to dashboard Cite

Lignin biodegradation has been extensively studied in white-rot fungi, which largely belong to order Polyporales. Among the enzymes that wood-rotting polypores secrete, lignin peroxidases (LiPs) have been labeled as the most efficient. Here, we characterize a similar enzyme (ApeLiP) from a fungus of the order Agaricales (with ~13,000 described species), the soil-inhabiting mushroom Agrocybe pediades. X-ray crystallography revealed that ApeLiP is structurally related to Polyporales LiPs, with a conserved heme-pocket and a solvent-exposed tryptophan. Its biochemical characterization shows that ApeLiP can oxidize both phenolic and non-phenolic lignin model-compounds, as well as different dyes. Moreover, using stopped-flow rapid spectrophotometry and 2D-NMR, we demonstrate that ApeLiP can also act on real lignin. Characterization of a variant lacking the above tryptophan residue shows that this is the oxidation site for lignin and other high redox-potential substrates, and also plays a role in phenolic substrate oxidation. The reduction potentials of the catalytic-cycle intermediates were estimated by stopped-flow in equilibrium reactions, showing similar activation by H2O2, but a lower potential for the rate-limiting step (compound-II reduction) compared to other LiPs. Unexpectedly, ApeLiP was stable from acidic to basic pH, a relevant feature for application considering its different optima for oxidation of phenolic and nonphenolic compounds.

show abstract

“…Prior to Fourier transformation, the data matrices were zero-filled to 1024 points in the 13 C dimension. Signals were assigned by literature comparison [ 32 , 51 , 58 , 69 – 72 ].…”

Section: Methodsmentioning

confidence: 99%

Role of surface tryptophan for peroxidase oxidation of nonphenolic lignin

Sáez-Jiménez

Rencoret

Rodrı́guez-Carvajal

et al. 2016

Biotechnol Biofuels

View full text Add to dashboard Cite

BackgroundDespite claims as key enzymes in enzymatic delignification, very scarce information on the reaction rates between the ligninolytic versatile peroxidase (VP) and lignin peroxidase (LiP) and the lignin polymer is available, due to methodological difficulties related to lignin heterogeneity and low solubility.ResultsTwo water-soluble sulfonated lignins (from Picea abies and Eucalyptus grandis) were chemically characterized and used to estimate single electron-transfer rates to the H2O2-activated Pleurotus eryngii VP (native enzyme and mutated variant) transient states (compounds I and II bearing two- and one-electron deficiencies, respectively). When the rate-limiting reduction of compound II was quantified by stopped-flow rapid spectrophotometry, from fourfold (softwood lignin) to over 100-fold (hardwood lignin) lower electron-transfer efficiencies (k 3app values) were observed for the W164S variant at surface Trp164, compared with the native VP. These lignosulfonates have ~20–30 % phenolic units, which could be responsible for the observed residual activity. Therefore, methylated (and acetylated) samples were used in new stopped-flow experiments, where negligible electron transfer to the W164S compound II was found. This revealed that the residual reduction of W164S compound II by native lignin was due to its phenolic moiety. Since both native lignins have a relatively similar phenolic moiety, the higher W164S activity on the softwood lignin could be due to easier access of its mono-methoxylated units for direct oxidation at the heme channel in the absence of the catalytic tryptophan. Moreover, the lower electron transfer rates from the derivatized lignosulfonates to native VP suggest that peroxidase attack starts at the phenolic lignin moiety. In agreement with the transient-state kinetic data, very low structural modification of lignin, as revealed by size-exclusion chromatography and two-dimensional nuclear magnetic resonance, was obtained during steady-state treatment (up to 24 h) of native lignosulfonates with the W164S variant compared with native VP and, more importantly, this activity disappeared when nonphenolic lignosulfonates were used.ConclusionsWe demonstrate for the first time that the surface tryptophan conserved in most LiPs and VPs (Trp164 of P. eryngii VPL) is strictly required for oxidation of the nonphenolic moiety, which represents the major and more recalcitrant part of the lignin polymer.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-016-0615-x) contains supplementary material, which is available to authorized users.

show abstract

Study on the residual lignin in Eucalyptus globulus sulphite pulp

Cited by 20 publications

References 18 publications

Demonstration of Lignin-to-Peroxidase Direct Electron Transfer

Demonstration of Lignin-to-Peroxidase Direct Electron Transfer

Agaricales Mushroom Lignin Peroxidase: From Structure–Function to Degradative Capabilities

Role of surface tryptophan for peroxidase oxidation of nonphenolic lignin

Contact Info

Product

Resources

About