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PDBsum entry 3lpo

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protein ligands Protein-protein interface(s) links
Hydrolase PDB id
3lpo
Jmol
Contents
Protein chain
870 a.a. *
Ligands
NAG ×5
NAG-NAG ×2
NAG-NAG-BMA-MAN-
MAN
×2
* Residue conservation analysis
PDB id:
3lpo
Name: Hydrolase
Title: Crystal structure of the n-terminal domain of sucrase-isomal
Structure: Sucrase-isomaltase. Chain: a, b, c, d. Fragment: n-terminal domain. Synonym: sucrase, isomaltase. Engineered: yes
Source: Homo sapiens. Human. Organism_taxid: 9606. Gene: si. Expressed in: drosophila melanogaster. Expression_system_taxid: 7227. Expression_system_cell: s2 cells.
Resolution:
3.20Å     R-factor:   0.227     R-free:   0.251
Authors: L.Sim,D.R.Rose
Key ref: L.Sim et al. (2010). Structural basis for substrate selectivity in human maltase-glucoamylase and sucrase-isomaltase N-terminal domains. J Biol Chem, 285, 17763-17770. PubMed id: 20356844
Date:
05-Feb-10     Release date:   31-Mar-10    
PROCHECK
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 Headers
 References

Protein chains
Pfam   ArchSchema ?
P14410  (SUIS_HUMAN) -  Sucrase-isomaltase, intestinal
Seq:
Struc:
 
Seq:
Struc:
 
Seq:
Struc:
 
Seq:
Struc:
1827 a.a.
870 a.a.*
Key:    PfamA domain  PfamB domain  Secondary structure  CATH domain
* PDB and UniProt seqs differ at 1 residue position (black cross)

 Enzyme reactions 
   Enzyme class 1: E.C.3.2.1.10  - Oligo-1,6-glucosidase.
[IntEnz]   [ExPASy]   [KEGG]   [BRENDA]
      Reaction: Hydrolysis of 1,6-alpha-D-glucosidic linkages in some oligosaccharides produced from starch and glycogen by alpha-amylase, and in isomaltose.
   Enzyme class 2: E.C.3.2.1.48  - Sucrose alpha-glucosidase.
[IntEnz]   [ExPASy]   [KEGG]   [BRENDA]
      Reaction: Hydrolysis of sucrose and maltose by an alpha-D-glucosidase-type action.
Note, where more than one E.C. class is given (as above), each may correspond to a different protein domain or, in the case of polyprotein precursors, to a different mature protein.
 Gene Ontology (GO) functional annotation 
  GO annot!
  Biological process     carbohydrate metabolic process   1 term 
  Biochemical function     catalytic activity     3 terms  

 

 
J Biol Chem 285:17763-17770 (2010)
PubMed id: 20356844  
 
 
Structural basis for substrate selectivity in human maltase-glucoamylase and sucrase-isomaltase N-terminal domains.
L.Sim, C.Willemsma, S.Mohan, H.Y.Naim, B.M.Pinto, D.R.Rose.
 
  ABSTRACT  
 
Human maltase-glucoamylase (MGAM) and sucrase-isomaltase (SI) are small intestinal enzymes that work concurrently to hydrolyze the mixture of linear alpha-1,4- and branched alpha-1,6-oligosaccharide substrates that typically make up terminal starch digestion products. MGAM and SI are each composed of duplicated catalytic domains, N- and C-terminal, which display overlapping substrate specificities. The N-terminal catalytic domain of human MGAM (ntMGAM) has a preference for short linear alpha-1,4-oligosaccharides, whereas N-terminal SI (ntSI) has a broader specificity for both alpha-1,4- and alpha-1,6-oligosaccharides. Here we present the crystal structure of the human ntSI, in apo form to 3.2 A and in complex with the inhibitor kotalanol to 2.15 A resolution. Structural comparison with the previously solved structure of ntMGAM reveals key active site differences in ntSI, including a narrow hydrophobic +1 subsite, which may account for its additional substrate specificity for alpha-1,6 substrates.