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Characterization of an inducible chlorophenol O-methyltransferase from Trichoderma longibrachiatum involved in the formation of chloroanisoles and determination of its role in cork taint of wines.

Abstract：

:A novel S-adenosyl-L-methionine (SAM)-dependent methyltransferase catalyzing the O methylation of several chlorophenols and other halogenated phenols was purified 220-fold to apparent homogeneity from mycelia of Trichoderma longibrachiatum CECT 20431. The enzyme could be identified in partially purified protein preparations by direct photolabeling with [methyl-(3)H]SAM, and this reaction was prevented by previous incubation with S-adenosylhomocysteine. Gel filtration indicated that the M(r) was 112,000, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that the enzyme was composed of two subunits with molecular weights of approximately 52,500. The enzyme had a pH optimum between 8.2 and 8.5 and an optimum temperature of 28 degrees C, with a pI of 4.9. The K(m) values for 2,4,6-trichlorophenol and SAM were 135.9 +/- 12.8 and 284.1 +/- 35.1 micro M, respectively. S-Adenosylhomocysteine acted as a competitive inhibitor, with a K(i) of 378.9 +/- 45.4 micro M. The methyltransferase was also strongly inhibited by low concentrations of several metal ions, such as Cu(2+), Hg(2+), Zn(2+), and Ag(+), and to a lesser extent by p-chloromercuribenzoic acid, but it was not significantly affected by several thiols or other thiol reagents. The methyltransferase was specifically induced by several chlorophenols, especially if they contained three or more chlorine atoms in their structures. Substrate specificity studies showed that the activity was also specific for halogenated phenols containing fluoro, chloro, or bromo substituents, whereas other hydroxylated compounds, such as hydroxylated benzoic acids, hydroxybenzaldehydes, phenol, 2-metoxyphenol, and dihydroxybenzene, were not methylated.

journal_name

Appl Environ Microbiol

journal_title

Applied and environmental microbiology

authors

Coque JJ,Alvarez-Rodríguez ML,Larriba G

doi

10.1128/aem.69.9.5089-5095.2003

keywords:

subject

Has Abstract

pub_date

2003-09-01 00:00:00

pages

5089-95

issue

eissn

0099-2240

issn

1098-5336

journal_volume

pub_type

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Characterization of an inducible chlorophenol O-methyltransferase from Trichoderma longibrachiatum involved in the formation of chloroanisoles and determination of its role in cork taint of wines.