4IUZ

High resolution crystal structure of racemic ester insulin

Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.60 Å
  • R-Value Free: 0.249 
  • R-Value Work: 0.221 
  • R-Value Observed: 0.222 

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This is version 1.1 of the entry. See complete history. 


Literature

Fully Convergent Chemical Synthesis of Ester Insulin: Determination of the High Resolution X-ray Structure by Racemic Protein Crystallography.

Avital-Shmilovici, M., Mandal, K., Gates, Z.P., Phillips, N.B., Weiss, M.A., Kent, S.B.

(2013) J Am Chem Soc 135: 3173-3185

  • DOI: 10.1021/ja311408y
  • Primary Citation of Related Structures:  
    4IUZ

  • PubMed Abstract: 

    • Efficient total synthesis of insulin is important to enable the application of medicinal chemistry to the optimization of the properties of this important protein molecule. Recently we described "ester insulin"--a novel form of insulin in which the funct ...

    Efficient total synthesis of insulin is important to enable the application of medicinal chemistry to the optimization of the properties of this important protein molecule. Recently we described "ester insulin"--a novel form of insulin in which the function of the 35 residue C-peptide of proinsulin is replaced by a single covalent bond--as a key intermediate for the efficient total synthesis of insulin. Here we describe a fully convergent synthetic route to the ester insulin molecule from three unprotected peptide segments of approximately equal size. The synthetic ester insulin polypeptide chain folded much more rapidly than proinsulin, and at physiological pH. Both the D-protein and L-protein enantiomers of monomeric DKP ester insulin (i.e., [Asp(B10), Lys(B28), Pro(B29)]ester insulin) were prepared by total chemical synthesis. The atomic structure of the synthetic ester insulin molecule was determined by racemic protein X-ray crystallography to a resolution of 1.6 Å. Diffraction quality crystals were readily obtained from the racemic mixture of {D-DKP ester insulin + L-DKP ester insulin}, whereas crystals were not obtained from the L-ester insulin alone even after extensive trials. Both the D-protein and L-protein enantiomers of monomeric DKP ester insulin were assayed for receptor binding and in diabetic rats, before and after conversion by saponification to the corresponding DKP insulin enantiomers. L-DKP ester insulin bound weakly to the insulin receptor, while synthetic L-DKP insulin derived from the L-DKP ester insulin intermediate was fully active in binding to the insulin receptor. The D- and L-DKP ester insulins and D-DKP insulin were inactive in lowering blood glucose in diabetic rats, while synthetic L-DKP insulin was fully active in this biological assay. The structural basis of the lack of biological activity of ester insulin is discussed.

    Organizational Affiliation: 

    Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, USA.



Macromolecules
Find similar proteins by: 
(by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Insulin A chain A21Homo sapiensMutation(s): 0 
Gene Names: INS
Find proteins for P01308 (Homo sapiens)
Explore P01308 
Go to UniProtKB:  P01308
NIH Common Fund Data Resources
PHAROS:  P01308
Protein Feature View
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  • Reference Sequence
Find similar proteins by: 
(by identity cutoff)  |  Structure
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetailsImage
Insulin B chain B30Homo sapiensMutation(s): 3 
Gene Names: INS
Find proteins for P01308 (Homo sapiens)
Explore P01308 
Go to UniProtKB:  P01308
NIH Common Fund Data Resources
PHAROS:  P01308
Protein Feature View
Expand
  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
PEG
Query on PEG
Download Ideal Coordinates CCD File 
B
DI(HYDROXYETHYL)ETHER
C4 H10 O3
MTHSVFCYNBDYFN-UHFFFAOYSA-N		 Ligand Interaction
GOL
Query on GOL
Download Ideal Coordinates CCD File 
B
GLYCEROL
C3 H8 O3
PEDCQBHIVMGVHV-UHFFFAOYSA-N		 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.60 Å
  • R-Value Free: 0.249 
  • R-Value Work: 0.221 
  • R-Value Observed: 0.222 
  • Space Group: P -1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 20.495α = 96.42
b = 27.757β = 98.6
c = 34.765γ = 104.46
Software Package:
Software NamePurpose
SCALEPACKdata scaling
REFMACrefinement
PDB_EXTRACTdata extraction
HKL-2000data reduction
HKL-2000data scaling
MOLREPphasing

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2013-02-13
    Type: Initial release
  • Version 1.1: 2013-03-20
    Changes: Database references