Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.10.3.2 (laccase)
 4,656 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Degradation of technical nonylphenol (t-NP), known as an endocrine-disrupting compound mixture, was assessed, using the mitosporic fungal strain UHH 1-6-18-4 isolated from nonylphenol-contaminated river water, and a strain of the aquatic hyphomycete Clavariopsis aquatica. GC-MS analysis could resolve 12 peaks attributable to nonyl chain-branched t-NP isomers. All were degraded, to individual extents. Analysis of degradation metabolites suggested intracellular hydroxylation of the nonyl moieties of individual t-NP isomers. Further metabolites also indicated shortening of branched nonyl chains, and 4-hydroxybenzoic acid was identified as a t-NP breakdown product in UHH 1-6-18-4. The t-NP degradation efficiency was higher in UHH 1-6-18-4 than in C. aquatica, and a lower specificity in degradation of individual t-NP constituents in UHH 1-6-18-4 than in C. aquatica was observed. Strain UHH 1-6-18-4 concomitantly produced extracellular laccase under degradation conditions. A mixture of CuSO(4) and vanillic acid considerably enhanced laccase production in both fungi. Laccase preparations derived from UHH 1-6-18-4 and C. aquatica cultures also converted t-NP. Laccase-catalysed transformation of t-NP led to the formation of products with higher molecular masses than that of the parent compound. These results emphasize a role of fungi occurring in aquatic ecosystems in degradation of water contaminants with endocrine activity, which has not previously been considered. Furthermore, the results are in support of two different mechanisms employed by fungi isolated from aquatic environments to initiate t-NP degradation: hydroxylation of individual t-NP isomers at their branched nonyl chains and further breakdown of the alkyl chains of certain isomers; and attack of t-NP by extracellular laccase, the latter leading to oxidative coupling of primary radical products to compounds with higher molecular masses.
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PMID:Degradation of the xenoestrogen nonylphenol by aquatic fungi and their laccases. 1563 24

The aquatic hyphomycete Clavariopsis aquatica was used to quantify the effects of extracellular laccase and intracellular reactions on the isomer-specific biotransformation of technical nonylphenol (t-NP). In laccase-producing cultures, maximal removal rates of t-NP and the isomer 4-(1-ethyl-1,4-dimethylpentyl)phenol (NP112) were about 1.6- and 2.4-fold higher, respectively, than in laccase-lacking cultures. The selective suppression of either laccase or intracellular reactions resulted in essentially comparable maximal removal rates for both compounds. Evidence for an unspecific oxidation of t-NP isomers was consistently obtained from laccase-expressing fungal cultures when intracellular biotransformation was suppressed and from reaction mixtures containing isolated laccase. This observation contrasts with the selective degradation of t-NP isomers by bacteria and should prevent the enrichment of highly estrogenic isomers in remaining t-NP. In contrast with laccase reactions, intracellular fungal biotransformation caused a significant shift in the isomeric composition of remaining t-NP. As a result, certain t-NP constituents related to more estrogenic isomers were less efficiently degraded than others. In contrast to bacterial degradation via ipso-hydroxylation, the substitution pattern of the quaternary alpha-carbon of t-NP isomers does not seem to be very important for intracellular transformation in C. aquatica. As-yet-unknown intracellular enzymes are obviously induced by nonylphenols. Mass spectral data of the metabolites resulting from the intracellular oxidation of t-NP, NP112, and 4-(1-ethyl-1,3-dimethylpentyl)phenol indicate nonyl chain hydroxylation, further oxidation into keto or aldehyde compounds, and the subsequent formation of carboxylic acid derivatives. Further metabolites suggest nonyl chain desaturation and methylation of carboxylic acids. The phenolic moieties of the nonylphenols remained unchanged.
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PMID:Quantification of the influence of extracellular laccase and intracellular reactions on the isomer-specific biotransformation of the xenoestrogen technical nonylphenol by the aquatic hyphomycete Clavariopsis aquatica. 1942 59