3a4a

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Crystal structure of isomaltase from Saccharomyces cerevisiae

Structural highlights

3a4a is a 1 chain structure with sequence from Saccharomyces cerevisiae. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:X-ray diffraction, Resolution 1.6Å
Ligands:CA, GLC
Resources:FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

MALX3_YEAST Major isomaltase (alpha-1,6-glucosidase) required for isomaltose utilization. Preferentially hydrolyzes isomaltose, palatinose, and methyl-alpha-glucoside, with little activity towards isomaltotriose or longer oligosaccharides. Does not hydrolyze maltose.[1] [2]

Evolutionary Conservation

Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.

Publication Abstract from PubMed

The structures of isomaltase from Saccharomyces cerevisiae and in complex with maltose were determined at resolutions of 1.30 and 1.60 A, respectively. Isomaltase contains three domains, namely, A, B, and C. Domain A consists of the (beta/alpha)(8) -barrel common to glycoside hydrolase family 13. However, the folding of domain C is rarely seen in other glycoside hydrolase family 13 enzymes. An electron density corresponding to a nonreducing end glucose residue was observed in the active site of isomaltase in complex with maltose; however, only incomplete density was observed for the reducing end. The active site pocket contains two water chains. One water chain is a water path from the bottom of the pocket to the surface of the protein, and may act as a water drain during substrate binding. The other water chain, which consists of six water molecules, is located near the catalytic residues Glu277 and Asp352. These water molecules may act as a reservoir that provides water for subsequent hydrolytic events. The best substrate for oligo-1,6-glucosidase is isomaltotriose; other, longer-chain, oligosaccharides are also good substrates. However, isomaltase shows the highest activity towards isomaltose and very little activity towards longer oligosaccharides. This is because the entrance to the active site pocket of isomaltose is severely narrowed by Tyr158, His280, and loop 310-315, and because the isomaltase pocket is shallower than that of other oligo-1,6-glucosidases. These features of the isomaltase active site pocket prevent isomalto-oligosaccharides from binding to the active site effectively.

Crystal structures of isomaltase from Saccharomyces cerevisiae and in complex with its competitive inhibitor maltose.,Yamamoto K, Miyake H, Kusunoki M, Osaki S FEBS J. 2010 Oct;277(20):4205-14. doi: 10.1111/j.1742-4658.2010.07810.x., Epub 2010 Aug 31. PMID:20812985[3]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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See Also

References

  1. Yamamoto K, Nakayama A, Yamamoto Y, Tabata S. Val216 decides the substrate specificity of alpha-glucosidase in Saccharomyces cerevisiae. Eur J Biochem. 2004 Aug;271(16):3414-20. PMID:15291818 doi:10.1111/j.1432-1033.2004.04276.x
  2. Teste MA, Francois JM, Parrou JL. Characterization of a new multigene family encoding isomaltases in the yeast Saccharomyces cerevisiae, the IMA family. J Biol Chem. 2010 Aug 27;285(35):26815-24. doi: 10.1074/jbc.M110.145946. Epub, 2010 Jun 18. PMID:20562106 doi:10.1074/jbc.M110.145946
  3. Yamamoto K, Miyake H, Kusunoki M, Osaki S. Crystal structures of isomaltase from Saccharomyces cerevisiae and in complex with its competitive inhibitor maltose. FEBS J. 2010 Oct;277(20):4205-14. doi: 10.1111/j.1742-4658.2010.07810.x., Epub 2010 Aug 31. PMID:20812985 doi:10.1111/j.1742-4658.2010.07810.x

Contents


PDB ID 3a4a

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