PDBsum entry 1snz

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protein links
Isomerase PDB id
Protein chain
344 a.a. *
Waters ×258
* Residue conservation analysis
PDB id:
Name: Isomerase
Title: Crystal structure of apo human galactose mutarotase
Structure: Aldose 1-epimerase. Chain: a, b. Synonym: galactose mutarotase. Engineered: yes
Source: Homo sapiens. Human. Organism_taxid: 9606. Gene: galm. Expressed in: escherichia coli. Expression_system_taxid: 562.
2.20Å     R-factor:   0.174     R-free:   0.201
Authors: J.B.Thoden,D.J.Timson,R.J.Reece,H.M.Holden
Key ref:
J.B.Thoden et al. (2004). Molecular structure of human galactose mutarotase. J Biol Chem, 279, 23431-23437. PubMed id: 15026423 DOI: 10.1074/jbc.M402347200
12-Mar-04     Release date:   30-Mar-04    
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Protein chains
Pfam   ArchSchema ?
Q96C23  (GALM_HUMAN) -  Aldose 1-epimerase
342 a.a.
344 a.a.
Key:    PfamA domain  Secondary structure  CATH domain

 Enzyme reactions 
   Enzyme class: E.C.  - Aldose 1-epimerase.
[IntEnz]   [ExPASy]   [KEGG]   [BRENDA]
      Reaction: Alpha-D-glucose = beta-D-glucose
= beta-D-glucose
Molecule diagrams generated from .mol files obtained from the KEGG ftp site
 Gene Ontology (GO) functional annotation 
  GO annot!
  Cellular component     cytoplasm   2 terms 
  Biological process     carbohydrate metabolic process   4 terms 
  Biochemical function     catalytic activity     4 terms  


    Added reference    
DOI no: 10.1074/jbc.M402347200 J Biol Chem 279:23431-23437 (2004)
PubMed id: 15026423  
Molecular structure of human galactose mutarotase.
J.B.Thoden, D.J.Timson, R.J.Reece, H.M.Holden.
Galactose mutarotase catalyzes the conversion of beta-d-galactose to alpha-d-galactose during normal galactose metabolism. The enzyme has been isolated from bacteria, plants, and animals and is present in the cytoplasm of most cells. Here we report the x-ray crystallographic analysis of human galactose mutarotase both in the apoform and complexed with its substrate, beta-d-galactose. The polypeptide chain folds into an intricate array of 29 beta-strands, 25 classical reverse turns, and 2 small alpha-helices. There are two cis-peptide bonds at Arg-78 and Pro-103. The sugar ligand sits in a shallow cleft and is surrounded by Asn-81, Arg-82, His-107, His-176, Asp-243, Gln-279, and Glu-307. Both the side chains of Glu-307 and His-176 are in the proper location to act as a catalytic base and a catalytic acid, respectively. These residues are absolutely conserved among galactose mutarotases. To date, x-ray models for three mutarotases have now been reported, namely that described here and those from Lactococcus lactis and Caenorhabditis elegans. The molecular architectures of these enzymes differ primarily in the loop regions connecting the first two beta-strands. In the human protein, there are six extra residues in the loop compared with the bacterial protein for an approximate longer length of 9 A. In the C. elegans protein, the first 17 residues are missing, thereby reducing the total number of beta-strands by one.
  Selected figure(s)  
Figure 2.
FIG. 2. Structure of human galactose mutarotase. A ribbon representation of the three-dimensional architecture exhibited by the apoenzyme is shown in a. For clarity, only the major strands of the -sheet are displayed. Asterisks indicate the positions of cis-Arg-78 and cis-Pro-103. The location of the active site is depicted in b as a space-filling representation. Note that the 3-, 4-, and 6-hydroxyl groups of galactose, from left to right and indicated by the red spheres, are solvent-exposed. The view is approximately the same as displayed in a.
Figure 3.
FIG. 3. The active site for human galactose mutarotase. A close-up stereo view of those amino acid residues involved in sugar binding is displayed in a. The color coding for the ribbon representation is the same as in Fig. 2. The sugar is highlighted in grayish bonds. Possible hydrogen bonding interactions between the protein and the ligand are shown schematically in b. The dotted lines indicate distances equal to or below 3.2 Å.
  The above figures are reprinted by permission from the ASBMB: J Biol Chem (2004, 279, 23431-23437) copyright 2004.  
  Figures were selected by an automated process.  

Literature references that cite this PDB file's key reference

  PubMed id Reference
  20944213 C.Bakolitsa, A.Kumar, D.McMullan, S.S.Krishna, M.D.Miller, D.Carlton, R.Najmanovich, P.Abdubek, T.Astakhova, H.J.Chiu, T.Clayton, M.C.Deller, L.Duan, Y.Elias, J.Feuerhelm, J.C.Grant, S.K.Grzechnik, G.W.Han, L.Jaroszewski, K.K.Jin, H.E.Klock, M.W.Knuth, P.Kozbial, D.Marciano, A.T.Morse, E.Nigoghossian, L.Okach, S.Oommachen, J.Paulsen, R.Reyes, C.L.Rife, C.V.Trout, H.van den Bedem, D.Weekes, A.White, Q.Xu, K.O.Hodgson, J.Wooley, M.A.Elsliger, A.M.Deacon, A.Godzik, S.A.Lesley, and I.A.Wilson (2010).
The structure of the first representative of Pfam family PF06475 reveals a new fold with possible involvement in glycolipid metabolism.
  Acta Crystallogr Sect F Struct Biol Cryst Commun, 66, 1211-1217.
PDB code: 2h1t
19859980 K.Lai, L.J.Elsas, and K.J.Wierenga (2009).
Galactose toxicity in animals.
  IUBMB Life, 61, 1063-1074.  
17253981 A.Scott, and D.J.Timson (2007).
Characterization of the Saccharomyces cerevisiae galactose mutarotase/UDP-galactose 4-epimerase protein, Gal10p.
  FEMS Yeast Res, 7, 366-371.  
18052213 T.Pai, Q.Chen, Y.Zhang, R.Zolfaghari, and A.C.Ross (2007).
Galactomutarotase and other galactose-related genes are rapidly induced by retinoic acid in human myeloid cells.
  Biochemistry, 46, 15198-15207.  
The most recent references are shown first. Citation data come partly from CiteXplore and partly from an automated harvesting procedure. Note that this is likely to be only a partial list as not all journals are covered by either method. However, we are continually building up the citation data so more and more references will be included with time. Where a reference describes a PDB structure, the PDB code is shown on the right.