کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4416351 1307778 2006 12 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Coupling of 2,4,6-trinitrotoluene (TNT) metabolites onto humic monomers by a new laccase from Trametes modesta
موضوعات مرتبط
علوم زیستی و بیوفناوری علوم محیط زیست شیمی زیست محیطی
پیش نمایش صفحه اول مقاله
Coupling of 2,4,6-trinitrotoluene (TNT) metabolites onto humic monomers by a new laccase from Trametes modesta
چکیده انگلیسی

During degradation of trinitrotoluene (TNT) by Trametes modesta, addition of humic monomers prevented the accumulation of all major stable TNT metabolites (aminodinitrotoluenes [AMDNT]) by at least 92% in the presence of 200 mM ferulic acid and guaiacol. Acute toxicity tests with individual TNT metabolites and in T. modesta cultures supplemented with 200 μM TNT demonstrated that the TNT biodegradation process lead to less toxic metabolites. Toxicity decreased in the order TNT > 4-HADNT (4-hydroxylaminodinitrotoluene) > 2-HADNT > 2,6-DNT (2,6-dinitrotoluene) > 2′,2′,6,6-azoxytetranitrotoluene > 4-AMDNT > 2-AMDNT > 2,4-diamninonitrotoluene (2,4-DAMNT) while 2,4-DNT and 2,6-DAMNT were the least toxic. Ferulic acid is the best candidate for immobilization TNT biodegradation metabolites since it prevented the accumulation of AMDNTs in cultures during TNT biodegradation and its products were less toxic. All humic monomers were very effective in immobilizing 2-HADNT [100%], 4-HADNT [100%] and 2,2,6,6-azoxytetranitrotoluene [100%]. Two distinct laccase isoenzymes (LTM1 and LTM2) potentially involved in immobilization of TNT degradation products were purified to electrophoretic homogeneity. LTM1 and LTM2 have molecular weights of 77.6 and 52.5 kDa, are 18% and 24% glycosylated, have pI values of 3.6 and 4.2, respectively. Both enzymes oxidized all the typical laccase substrates tested. LTM1 showed highest kinetic constants (Km = 0.03 μM; Kcat = 8.84 × 107 s−1) with syringaldazine as substrate.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Chemosphere - Volume 64, Issue 3, June 2006, Pages 359–370
نویسندگان
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