CAZypedia celebrates the life of Senior Curator Emeritus Harry Gilbert, a true giant in the field, who passed away in September 2025.
CAZypedia needs your help!
We have many unassigned pages in need of Authors and Responsible Curators. See a page that's out-of-date and just needs a touch-up? - You are also welcome to become a CAZypedian. Here's how.
Scientists at all career stages, including students, are welcome to contribute.
Learn more about CAZypedia's misson here and in this article. Totally new to the CAZy classification? Read this first.
Difference between revisions of "Glycoside Hydrolase Family 93"
m |
|||
| Line 23: | Line 23: | ||
== Substrate specificities == | == Substrate specificities == | ||
| − | The characterized | + | The characterized [[glycoside hydrolases]] of family GH93 are known to hydrolyse linear α-1,5-L-arabinan. <cite>1</cite>, <cite>2</cite>, |
EC:3.2.1-. | EC:3.2.1-. | ||
== Kinetics and Mechanism == | == Kinetics and Mechanism == | ||
| − | GH93 enzymes are | + | GH93 enzymes are [[exo]]-acting enzymes that only release arabinobiose from the non-reducing end of α-1,5-L-arabinan. These enzymes are proposed to be [[retaining]] enzymes based on the net retention of the configuration of the anomeric carbon is proposed from the products of the transglycosylation activity of the protein Abnx from ''Penicillium chrysogenum'' <cite>3</cite>. This proposal obtained recent support from the crystal structure of the Arb93A enzyme from ''Fusarium graminearum'' in complex with arabinobiose, the degradation product of alpha-methyl-arabinotetraose. <cite>2</cite> |
== Catalytic Residues == | == Catalytic Residues == | ||
| − | From the crystal structure of Arb93A, Glu170 and Glu242 are proposed to act as nucleophile and acid/base respectively. Mutagenesis experiment support their role in catalysis and they are strictly conserved among the family members. <cite>2</cite> | + | From the crystal structure of Arb93A, Glu170 and Glu242 are proposed to act as [[catalytic nucleophile]] and [[general acid/base]] respectively. Mutagenesis experiment support their role in catalysis and they are strictly conserved among the family members. <cite>2</cite> |
== Three-dimensional structures == | == Three-dimensional structures == | ||
| Line 42: | Line 42: | ||
This was determined with the ''Penicillium chrysogenum'' Abxn enzyme using <sup>1</sup>H-NMR to identify the transglycosylation products <cite>3</cite> | This was determined with the ''Penicillium chrysogenum'' Abxn enzyme using <sup>1</sup>H-NMR to identify the transglycosylation products <cite>3</cite> | ||
| − | '''First catalytic nucleophile identification''' | + | '''First [[catalytic nucleophile]] identification''' |
This was proposed based on the structure of ''Fusarium graminearum'' Arb93A <cite>2</cite> | This was proposed based on the structure of ''Fusarium graminearum'' Arb93A <cite>2</cite> | ||
| − | '''First general acid/base residue identification''' | + | '''First [[general acid/base]] residue identification''' |
This was proposed based on the structure of ''Fusarium graminearum'' Arb93A <cite>2</cite> | This was proposed based on the structure of ''Fusarium graminearum'' Arb93A <cite>2</cite> | ||
Revision as of 20:39, 31 August 2009
| Glycoside Hydrolase Family GH93 | |
| Clan | GH-E |
| Mechanism | retaining |
| Active site residues | known |
| CAZy DB link | |
| http://www.cazy.org/fam/GH93.html | |
Substrate specificities
The characterized glycoside hydrolases of family GH93 are known to hydrolyse linear α-1,5-L-arabinan. [1], [2], EC:3.2.1-.
Kinetics and Mechanism
GH93 enzymes are exo-acting enzymes that only release arabinobiose from the non-reducing end of α-1,5-L-arabinan. These enzymes are proposed to be retaining enzymes based on the net retention of the configuration of the anomeric carbon is proposed from the products of the transglycosylation activity of the protein Abnx from Penicillium chrysogenum [3]. This proposal obtained recent support from the crystal structure of the Arb93A enzyme from Fusarium graminearum in complex with arabinobiose, the degradation product of alpha-methyl-arabinotetraose. [2]
Catalytic Residues
From the crystal structure of Arb93A, Glu170 and Glu242 are proposed to act as catalytic nucleophile and general acid/base respectively. Mutagenesis experiment support their role in catalysis and they are strictly conserved among the family members. [2]
Three-dimensional structures
The crystal structure of Arb93A reveals a six-bladed beta-propeller fold characteristic of sialidases of clan GHE. [2], [4] The catalytic machinery is however very different from that of sialidases.
Family Firsts
First sterochemistry determination
This was determined with the Penicillium chrysogenum Abxn enzyme using 1H-NMR to identify the transglycosylation products [3]
First catalytic nucleophile identification This was proposed based on the structure of Fusarium graminearum Arb93A [2]
First general acid/base residue identification This was proposed based on the structure of Fusarium graminearum Arb93A [2]
First 3-D structure Determined for Fusarium graminearum Arb93A by Carapito and co-workers [2]
References
Error fetching PMID 19269961:
Error fetching PMID 15342117:
Error fetching PMID 8591030:
- Error fetching PMID 11425761:
- Error fetching PMID 19269961:
- Error fetching PMID 15342117:
- Error fetching PMID 8591030: