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2gl9
From Proteopedia
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| , resolution 2.00Å | |||||||
|---|---|---|---|---|---|---|---|
| Ligands: | and | ||||||
| Activity: | N(4)-(beta-N-acetylglucosaminyl)-L-asparaginase, with EC number 3.5.1.26 | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
Crystal Structure of Glycosylasparaginase-Substrate Complex
Overview
Glycosylasparaginase (GA) plays an important role in asparagine-linked glycoprotein degradation. A deficiency in the activity of human GA leads to a lysosomal storage disease named aspartylglycosaminuria. GA belongs to a superfamily of N-terminal nucleophile hydrolases that autoproteolytically generate their mature enzymes from inactive single chain protein precursors. The side-chain of the newly exposed N-terminal residue then acts as a nucleophile during substrate hydrolysis. By taking advantage of mutant enzyme of Flavobacterium meningosepticum GA with reduced enzymatic activity, we have obtained a crystallographic snapshot of a productive complex with its substrate (NAcGlc-Asn), at 2.0 A resolution. This complex structure provided us an excellent model for the Michaelis complex to examine the specific contacts critical for substrate binding and catalysis. Substrate binding induces a conformational change near the active site of GA. To initiate catalysis, the side-chain of the N-terminal Thr152 is polarized by the free alpha-amino group on the same residue, mediated by the side-chain hydroxyl group of Thr170. Cleavage of the amide bond is then accomplished by a nucleophilic attack at the carbonyl carbon of the amide linkage in the substrate, leading to the formation of an acyl-enzyme intermediate through a negatively charged tetrahedral transition state.
About this Structure
2GL9 is a Protein complex structure of sequences from Elizabethkingia meningoseptica. Full crystallographic information is available from OCA.
Reference
Crystallographic snapshot of a productive glycosylasparaginase-substrate complex., Wang Y, Guo HC, J Mol Biol. 2007 Feb 9;366(1):82-92. Epub 2006 Sep 26. PMID:17157318
Page seeded by OCA on Thu Mar 20 17:06:04 2008
Categories: Elizabethkingia meningoseptica | N(4)-(beta-N-acetylglucosaminyl)-L-asparaginase | Protein complex | Guo, H C. | Wang, Y. | ASN | NAG | Catalytic mechanism | Crystal structure | Electron-pair transfer | Enzyme-acyl intermediate | Enzyme-substrate complex | Glycosylasparaginase | Ntn-hydrolase | Nucleophilic attack | Oxyanion hole | Proton-relay network
