An α-glucuronidase of Schizophyllum commune acting on polymeric xylan

Maija Tenkanen (Corresponding Author), Matti Siika-aho

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118 Citations (Scopus)

Abstract

The main α-glucuronidase (EC 3.2.1.131) of the fungus Schizophyllum commune was purified to homogeneity using standard chromatographic methods; anion exchange, hydrophobic interaction chromatography and gel filtration. The enzyme had a molecular mass of 125 kDa as determined by SDS-polyacrylamide gel electrophoresis and a pI value of 3.6 according to isoelectric focusing. The N-terminal amino acid sequence of the S. commune α-glucuronidase did not show any homology with other α-glucuronidases. It exhibited maximal activity at pH values from 4.5 to 5.5 and was stable for 24 h between pH 6 and 8 at 40°C. The highest temperature at which the enzyme retained its full activity for 24 h at pH 5.8 was 40°C. The α-glucuronidase of S. commune was able to remove almost all 4-O-methylglucuronic acid groups from water-soluble polymeric softwood arabinoglucuronoxylans. The action of the enzyme on birchwood acetyl-glucuronoxylan was limited due to the high amount of acetyl substituents. The degree of hydrolysis of partially soluble deacetylated glucuronoxylan did not exceed 50% of the theoretical maximum. However, together with a xylanase hydrolysing the xylan backbone the action of the α-glucuronidase of S. commune on glucuronoxylan was clearly enhanced. It was apparent that the enzyme was able to remove the 4-O-methylglucuronic groups mainly from soluble substrates.

Original languageEnglish
Pages (from-to)149 - 161
Number of pages13
JournalJournal of Biotechnology
Volume78
Issue number2
DOIs
Publication statusPublished - 2000
MoE publication typeA1 Journal article-refereed

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