Affiliation:
1. Departments of Microbiology1 and
2. Chemistry,2 Montana State University, Bozeman, Montana 59717
Abstract
ABSTRACT
We purified a secreted fungal laccase from filtrates of
Gaeumannomyces graminis
var.
tritici
cultures induced with copper and xylidine. The active protein had an apparent molecular mass of 190 kDa and yielded subunits with molecular masses of 60 kDa when denatured and deglycosylated. This laccase had a pI of 5.6 and an optimal pH of 4.5 with 2,6-dimethoxyphenol as its substrate. Like other, previously purified laccases, this one contained several copper atoms in each subunit, as determined by inductively coupled plasma spectroscopy. The active enzyme catalyzed the oxidation of 2,6-dimethoxyphenol (
K
m
= 2.6 × 10
−5
± 7 × 10
−6
M), catechol (
K
m
= 2.5 × 10
−4
± 1 × 10
−5
M), pyrogallol (
K
m
= 3.1 × 10
−4
± 4 × 10
−5
M), and guaiacol (
K
m
= 5.1 × 10
−4
± 2 × 10
−5
M). In addition, the laccase catalyzed the polymerization of 1,8-dihydroxynaphthalene, a natural fungal melanin precursor, into a high-molecular-weight melanin and catalyzed the oxidation, or decolorization, of the dye poly B-411, a lignin-like polymer. These findings indicate that this laccase may be involved in melanin polymerization in this phytopathogen’s hyphae and/or in lignin depolymerization in its infected plant host.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
100 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献