Send to

Choose Destination
See comment in PubMed Commons below
Appl Environ Microbiol. 1997 Jul;63(7):2560-5.

Structure of a laccase-mediated product of coupling of 2,4-diamino-6-nitrotoluene to guaiacol, a model for coupling of 2,4,6-trinitrotoluene metabolites to a humic organic soil matrix.


This work presents laccase-mediated model reactions for coupling of reduced 2,4,6-trinitrotoluene (TNT) metabolites to an organic soil matrix. The structure of an isolated coupling product of 2,4-diamino-6-nitrotoluene (2,4-DANT) to guaiacol as humic constituent was determined. Among several structures, the compound was identified conclusively to be the trinuclear coupling product 5-(2-amino-3-methyl-4-nitroanilino)-3,3(prm1)-dimethoxy-4,4(prm1)-diphenoqu inone. The compound has a weight of 409 g mol(sup-1) and may serve as a model reaction for the biogenic formation of bound residues in soil from TNT by coupling aminotoluenes (reduced TNT metabolites) to humic constituents. A linear correlation of the substrate consumption to the enzyme activity was detected. Based on this observation, the described reaction of 2,4-DANT coupling to guaiacol may be used for determination of laccase activity since the reaction was not inhibited by other compounds of culture supernatants. We propose a two-step mechanism for the coupling reaction because 2,4-DANT was not transformed by laccases in the absence of guaiacol and guaiacol oxidation was independent of the presence of 2,4-DANT. The first reaction step is a laccase-mediated dimerization of two guaiacol monomers with subsequent oxidation to a diphenoquinone. The second step is the nucleophilic addition of 2,4-DANT to the ortho position of the carbonyl group of the diphenoquinone structure.

PubMed Commons home

PubMed Commons

How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for HighWire Icon for PubMed Central
    Loading ...
    Write to the Help Desk