Aspergillus aculeatus -1,4-Galactanase: Substrate Recognition and Relations to Other Glycoside Hydrolases in C
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- 作者：Carsten Ryttersgaard ; Leila Lo Leggio ; Pedro M. Coutinho ; Bernard Henrissat ; and Sine Larsen
- 刊名：Biochemistry
- 出版年：2002
- 出版时间：December 24, 2002
- 年：2002
- 卷：41
- 期：51
- 页码：15135 - 15143
- 全文大小：711K
- 年卷期：v.41,no.51(December 24, 2002)
- ISSN：1520-4995
文摘
The three-dimensional structure of Aspergillus aculeatus 
-1,4-galactanase (AAGAL), anenzyme involved in pectin degradation, has been determined by multiple isomorphous replacement to 2.3and 1.8 Å resolution at 293 and 100 K, respectively. It represents the first known structure for apolysaccharidase with this specificity and for a member of glycoside hydrolase family 53 (GH-53). Theenzyme folds into a (/
)8 barrel with the active site cleft located at the C-terminal side of the barrelconsistent with the classification of GH-53 in clan GH-A, a superfamily of enzymes with common foldand catalytic machinery but diverse specificities. Putative substrate-enzyme interactions were elucidatedby modeling of -1,4-linked galactobioses into the possible substrate binding subsites. The structure andmodeling studies identified five potential subsites for the binding of galactans, of which one is a pocketsuited for accommodating the arabinan side chain in arabinogalactan, one of the natural substrates. Acomparison with the substrate binding grooves of other Clan GH-A enzymes suggests that shapecomplementarity is crucial in determining the specificity of polysaccharidases.
-1,4-galactanase (AAGAL), anenzyme involved in pectin degradation, has been determined by multiple isomorphous replacement to 2.3and 1.8 Å resolution at 293 and 100 K, respectively. It represents the first known structure for apolysaccharidase with this specificity and for a member of glycoside hydrolase family 53 (GH-53). Theenzyme folds into a (/)8 barrel with the active site cleft located at the C-terminal side of the barrelconsistent with the classification of GH-53 in clan GH-A, a superfamily of enzymes with common foldand catalytic machinery but diverse specificities. Putative substrate-enzyme interactions were elucidatedby modeling of -1,4-linked galactobioses into the possible substrate binding subsites. The structure andmodeling studies identified five potential subsites for the binding of galactans, of which one is a pocketsuited for accommodating the arabinan side chain in arabinogalactan, one of the natural substrates. Acomparison with the substrate binding grooves of other Clan GH-A enzymes suggests that shapecomplementarity is crucial in determining the specificity of polysaccharidases.