Purification and characterization of an endo-β-(1→6)-galactanase from Trichoderma viride

An endo-β-(1→6)-galactanase from Onozuka R-10, a commercial cellulase preparation from Trichoderma viride, was purified 57-fold. Apparent M r values of the purified enzyme, estimated by denaturing gel electrophoresis and gel filtration, were 47,000 and 17,000, respectively. The enzyme was assayed wi...

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Bibliographic Details
Published in:Carbohydrate research 2003-01, Vol.338 (3), p.219-230
Main Authors: Okemoto, Kazuo, Uekita, Takamasa, Tsumuraya, Yoichi, Hashimoto, Yohichi, Kasama, Takeshi
Format: Article
Language:English
Subjects:
Arabinogalactan-protein
beta-Galactosidase - chemistry
beta-Galactosidase - isolation & purification
beta-Galactosidase - metabolism
Carbohydrase
Endo-β-(1→6)-galactanase
Fungal Proteins
Galactans - metabolism
Hydrogen-Ion Concentration
Hydrolysis
Molecular Weight
Substrate Specificity
Trichoderma - enzymology
Trichoderma viride
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Summary:An endo-β-(1→6)-galactanase from Onozuka R-10, a commercial cellulase preparation from Trichoderma viride, was purified 57-fold. Apparent M r values of the purified enzyme, estimated by denaturing gel electrophoresis and gel filtration, were 47,000 and 17,000, respectively. The enzyme was assayed with a galactan from Prototheca zopfii, which has a high proportion of β-(1→6)-linked galactosyl residues . It exhibited maximal activity toward the galactan at pH 4.3. The enzyme hydrolyzed specifically β-(1→6)-galactooligosaccharides with a degree of polymerization higher than 3 and their acidic derivatives with 4- O-methyl-glucosyluronic or glucosyluronic groups at the nonreducing terminals. The methyl β-glycoside of β-(1→6)-galactohexaose was degraded to reducing galactooligomers with a degree of polymerization 2–5 as the products at the initial stage of hydrolysis, and galactose and galactobiose at the final stage, indicating that the enzyme can be classified as an endo-galactanase. The extent of hydrolysis of the carbohydrate portion of a radish root arabinogalactan-protein (AGP) increased when α- l-arabinofuranosyl residues attached to β-(1→6)-linked galactosyl side chains of the AGP were removed in advance. The enzyme released galactose, β-(1→6)-galactobiose, and 4- O-methyl-β-glucuronosyl-(1→6)-galactose as major hydrolysis products when allowed to act exhaustively on the modified AGP. A fungal galactanase endo-hydrolyzed β-(1→6)-galactooligomers longer than DP 3. It liberated Gal and β-(1→6)-galactobiose from the β-3,6-galactan moieties of an arabinogalactan-protein.
ISSN:0008-6215
1873-426X
DOI:10.1016/S0008-6215(02)00405-6