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PDBsum entry 2oly

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protein ligands metals Protein-protein interface(s) links
Hormone PDB id
2oly
Jmol
Contents
Protein chains
(+ 0 more) 21 a.a.
28 a.a. *
29 a.a. *
Ligands
RCO ×8
URE ×7
GOL
Metals
_CL ×5
_ZN ×2
Waters ×235
* Residue conservation analysis
PDB id:
2oly
Name: Hormone
Title: Structure of human insulin in presence of urea at ph 7.0
Structure: Insulin a chain. Chain: a, c, e, g, i, k. Insulin b chain. Chain: b, d, f, h, j, l
Source: Homo sapiens. Human. Organism_taxid: 9606. Organism_taxid: 9606
Resolution:
1.70Å     R-factor:   0.186     R-free:   0.221
Authors: M.Norrman,G.Schluckebier
Key ref: M.Norrman and G.Schluckebier (2007). Crystallographic characterization of two novel crystal forms of human insulin induced by chaotropic agents and a shift in pH. BMC Struct Biol, 7, 83-83. PubMed id: 18093308
Date:
20-Jan-07     Release date:   04-Dec-07    
PROCHECK
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 Headers
 References

Protein chains
Pfam   ArchSchema ?
P01308  (INS_HUMAN) -  Insulin
Seq:
Struc:
110 a.a.
21 a.a.
Protein chains
Pfam   ArchSchema ?
P01308  (INS_HUMAN) -  Insulin
Seq:
Struc:
110 a.a.
28 a.a.
Protein chains
Pfam   ArchSchema ?
P01308  (INS_HUMAN) -  Insulin
Seq:
Struc:
110 a.a.
29 a.a.
Key:    PfamA domain  Secondary structure

 Gene Ontology (GO) functional annotation 
  GO annot!
  Cellular component     extracellular region   1 term 
  Biochemical function     hormone activity     1 term  

 

 
BMC Struct Biol 7:83-83 (2007)
PubMed id: 18093308  
 
 
Crystallographic characterization of two novel crystal forms of human insulin induced by chaotropic agents and a shift in pH.
M.Norrman, G.Schluckebier.
 
  ABSTRACT  
 
BACKGROUND: Insulin is a therapeutic protein that is widely used for the treatment of diabetes. Its biological function was discovered more than 80 years ago and it has since then been characterized extensively. Crystallization of the insulin molecule has always been a key activity since the protein is often administered by subcutaneous injections of crystalline insulin formulations. Over the years, insulin has been crystallized and characterized in a number of crystal systems. RESULTS: Interestingly, we have now discovered two new crystal forms of human insulin. The crystals were obtained when the two chaotropic agents, urea and thiocyanate were present in the crystallization experiments, and their structures were determined by X-ray crystallography. The crystals belong to the orthorhombic and monoclinic crystal systems, with space groups C2221 and C2 respectively. The orthorhombic crystals were obtained at pH 6.5 and contained three insulin hexamers in R6 conformation in the asymmetric unit whilst the monoclinic C2 crystals were obtained at pH 7.0 and contained one R6 hexamer in the asymmetric unit. Common for the two new crystals is a hexamer-hexamer interaction that has not been found in any of the previous crystal forms of insulin. The contacts involve a tight glutamate-glutamate interaction with a distance of 2.3 A between groups. The short distance suggests a low barrier hydrogen bond. In addition, two tyrosine-tyrosine interactions occupying a known phenol binding pocket contribute to the stabilization of the contacts. Within the crystals, distinct binding sites for urea were found, adding further to the discussion on the role of urea in protein denaturation. CONCLUSION: The change in space group from C2221 to C2 was primarily caused by an increase in pH. The fewer number of hexamer-hexamer interactions comprising the short hydrogen bond in the C2 space group suggest that pH is the driving force. In addition, the distance between the two glutamates increases from 2.32 A in the C2221 crystals to 2.4 A in the C2 crystals. However, in both cases the low barrier hydrogen bond and the tyrosine-tyrosine interaction should contribute to the stability of the crystals which is crucial when used in pharmaceutical formulations.