Article
Production of hydroxyl radical by the synergistic action of fungal laccase and aryl alcohol oxidase.
Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Madrid, Spain.
Archives of Biochemistry and Biophysics (impact factor:
2.93).
12/2000;
383(1):142-7.
DOI:10.1006/abbi.2000.2053
pp.142-7
Source: PubMed
-
Citations (0)
- Cited In (5)
-
Article: Biodegradation of lignocellulosics: microbial, chemical, and enzymatic aspects of the fungal attack of lignin.
[show abstract] [hide abstract]
ABSTRACT: Wood is the main renewable material on Earth and is largely used as building material and in paper-pulp manufacturing. This review describes the composition of lignocellulosic materials, the different processes by which fungi are able to alter wood, including decay patterns caused by white, brown, and soft-rot fungi, and fungal staining of wood. The chemical, enzymatic, and molecular aspects of the fungal attack of lignin, which represents the key step in wood decay, are also discussed. Modern analytical techniques to investigate fungal degradation and modification of the lignin polymer are reviewed, as are the different oxidative enzymes (oxidoreductases) involved in lignin degradation. These include laccases, high redox potential ligninolytic peroxidases (lignin peroxidase, manganese peroxidase, and versatile peroxidase), and oxidases. Special emphasis is given to the reactions catalyzed, their synergistic action on lignin, and the structural bases for their unique catalytic properties. Broadening our knowledge of lignocellulose biodegradation processes should contribute to better control of wood-decaying fungi, as well as to the development of new biocatalysts of industrial interest based on these organisms and their enzymes.International Microbiology 10/2005; 8(3):195-204. · 1.80 Impact Factor -
Article: Author's personal copy
[show abstract] [hide abstract]
ABSTRACT: a b s t r a c t Preparation of sol–gel derived materials with tailored porosity is a goal in fields such as catalysis, adsor-bents, separation media and sensors. The aim of this work was to study the simultaneous effects of pH (8–10), temperature (295–314 K), and ethanol:TEOS (6:1–12:1) and water:TEOS (2:1–6:1) molar ratios on the textural and structural properties of xerogels synthesized in alkaline media. We applied a 2 4 fac-torial design with five replicates of the central point to evaluate the effect of each independent variable and their interactions. Samples were characterized by XRD, SEM, TEM, FTIR, mercury porosimetry and gas adsorption (N 2 at 77 K and CO 2 at 273 K). The structural bonds in xerogels were similar; the siloxane microstructure did not change as a function of concentration of reagents and temperature. All xerogels were amorphous and mesoporous. Higher ethanol:TEOS molar ratios yielded xerogels with a higher spe-cific surface area, lower pore volume and average pore size, and narrower pore size distribution. On the other hand, increasing the water:TEOS molar ratio produced xerogels with a lower specific surface area and higher meso, macro and total pore volumes.Microporous and Mesoporous Materials 10/2008; · 3.29 Impact Factor -
Article: Effect of pH and oxalate on hydroquinone-derived hydroxyl radical formation during brown rot wood degradation.
[show abstract] [hide abstract]
ABSTRACT: The redox cycle of 2,5-dimethoxybenzoquinone (2,5-DMBQ) is proposed as a source of reducing equivalent for the regeneration of Fe2+ and H2O2 in brown rot fungal decay of wood. Oxalate has also been proposed to be the physiological iron reductant. We characterized the effect of pH and oxalate on the 2,5-DMBQ-driven Fenton chemistry and on Fe3+ reduction and oxidation. Hydroxyl radical formation was assessed by lipid peroxidation. We found that hydroquinone (2,5-DMHQ) is very stable in the absence of iron at pH 2 to 4, the pH of degraded wood. 2,5-DMHQ readily reduces Fe3+ at a rate constant of 4.5 x 10(3) M(-1)s(-1) at pH 4.0. Fe2+ is also very stable at a low pH. H2O2 generation results from the autoxidation of the semiquinone radical and was observed only when 2,5-DMHQ was incubated with Fe3+. Consistent with this conclusion, lipid peroxidation occurred only in incubation mixtures containing both 2,5-DMHQ and Fe3+. Catalase and hydroxyl radical scavengers were effective inhibitors of lipid peroxidation, whereas superoxide dismutase caused no inhibition. At a low concentration of oxalate (50 micro M), ferric ion reduction and lipid peroxidation are enhanced. Thus, the enhancement of both ferric ion reduction and lipid peroxidation may be due to oxalate increasing the solubility of the ferric ion. Increasing the oxalate concentration such that the oxalate/ferric ion ratio favored formation of the 2:1 and 3:1 complexes resulted in inhibition of iron reduction and lipid peroxidation. Our results confirm that hydroxyl radical formation occurs via the 2,5-DMBQ redox cycle.Applied and Environmental Microbiology 11/2003; 69(10):6025-31. · 3.83 Impact Factor
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed.
The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual
current impact factor.
Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence
agreement may be applicable.
Keywords
*OH formation
*OH generation
4-methoxybenzyl alcohol
aryl alcohol oxidase
chelated ferric ion
Fenton reaction
ferric ion reduction
ferrous ion
hydroxyl radical
laccase reaction
lignin-derived hydroquinones
main agents accomplishing
natural H2O2-producing system
P. eryngii
reaction mixtures
semiquinone autoxidation
semiquinone radicals
superoxide anion radical
synergistic action
white-rot fungi
