LACCASE COMPONENT OF THE CERIPORIOPSIS-SUBVEMISPORA LIGNIN-DEGRADING SYSTEM

被引:137
作者
FUKUSHIMA, Y
KIRK, TK
机构
[1] KIKKOMAN FOODS INC, DIV RES & DEV, NODA, CHIBA 278, JAPAN
[2] USDA, FOREST PROD LAB, INST MICROBIAL & BIOCHEM TECHNOL, MADISON, WI 53705 USA
[3] UNIV WISCONSIN, DEPT BACTERIOL, MADISON, WI 53706 USA
关键词
D O I
10.1128/AEM.61.3.872-876.1995
中图分类号
Q81 [生物工程学(生物技术)]; Q93 [微生物学];
学科分类号
071005 ; 0836 ; 090102 ; 100705 ;
摘要
Laccase activity in the lignin-degrading fungus Ceriporiopsis subvermispora was associated with several proteins in the broth of cultures grown in a defined medium, Activity,vas not increased significantly by adding 2,5-xylidine or supplemental copper to the medium, Higher activity, associated with two major isoenzymes, developed in cultures grown on a wheat bran medium. These two isoenzymes were purified to homogeneity. L1 and L2 had isoelectric points of 3.4 and 4.8, molecular masses of 71 and 68 kDa, and approximate carbohydrate contents of 15 and 10%, respectively, Data indicated 4 copper atoms per mel. L1 and L2 had overlapping pH optima in the range of 3 to 5, depending on the substrate, and exhibited half-lives of 120 acid 50 min at 60 degrees C., They were strongly inhibited by sodium azide and thioglycolic acid but not by hydroxylamine or EDTA, The isoenzymes oxidized 1,2,4,5-tetramethoxybenzene but not other methoxybenzene congeners, A variety of usual laccase substrates, including lignin-related phenols and ABTS [2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid)], were also oxidized, Kinetic parameters were similar to those of the laccases of Coriolus versicolor. The N-terminal amino acid sequence (20 residues for L1) showed significant homology to those of laccases of other white rot basidiomycetes but not to those of the laccases of Agaricus bisporus or Neurospora crassa.
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页码:872 / 876
页数:5
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