Substrate specificity of the alpha-L-arabinofuranosidase from Trichoderma reesei.
The precise substrate specificities of an alpha-L-arabinofuranosidase from Trichoderma reesei were investigated. The enzyme released arabinose at appreciable rates from p-nitrophenyl-alpha-L-arabinofuranoside, O-alpha-L-arabinofuranosyl-(1-->3)-O-beta-D-xylopyranosyl-(1-->4) -D-xylopyranose (A1X2), arabinan, arabinoxylan, arabinogalactan, debranched-arabinan and gum arabic, but not from O-beta-D-xylopyranosyl-(1-->4)-[O-alpha-L-arabinofuranosyl-(1-->3)] -O-beta-D-xylopyranosyl-(1-->4)-D-xylopyranose (A1X3) or O-beta-D-xylopyranosyl-(1-->2)-O-alpha-L-arabinofuranosyl -(1-->3)-O-beta-D-xylopyranosyl-(1-->4)-O-beta-D-xylopyranosyl-(-->4) -D-xylopyranose (A1X4). The enzyme hydrolyzed methyl 2-O-, methyl 3-O- and methyl 5-O-alpha-L-arabinofuranosyl-alpha-L-arabinofuranosides to arabinose and methyl alpha-L-arabinofuranoside with the order of hydrolysis being: (1-->5)- > (1-->2)- > or = (1-->3)-linkages. The enzyme hydrolyzed the (1-->3)-linkage faster than the (1-->5)-linkage of methyl 3,5-di-O-alpha-L-arabinofuranosyl-alpha-L-arabinofuranoside. The degree of conversion of arabinan and debranched-arabinan to monosaccharides by the enzyme was 33.0% and 9.1%, respectively. The alpha-L-arabinofuranosidase preferentially cleaved the arabinosyl side-chain from the arabinan rather than the terminal arabinosyl residue of the arabinan backbone.
Kaneko
S
S
Institute of Applied Biochemistry, University of Tsukuba, Japan. sakaneko@nfri.affrc.go.jp
Kuno
A
A
Matsuo
N
N
Ishii
T
T
Kobayashi
H
H
Hayashi
K
K
Kusakabe
I
I
D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D006026:Glycoside Hydrolases / Q000378:metabolism*; D006031:Glycosylation; D006868:Hydrolysis; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000378:metabolism*; D011134:Polysaccharides / Q000378:metabolism*; D013379:Substrate Specificity; D014242:Trichoderma / Q000201:enzymology*