1COS

CRYSTAL STRUCTURE OF A SYNTHETIC TRIPLE-STRANDED ALPHA-HELICAL BUNDLE

• PDB DOI: https://doi.org/10.2210/pdb1COS/pdb

• Classification: ALPHA-HELICAL BUNDLE
• Mutation(s): No 


• Deposited: 1993-01-22 Released: 1993-10-31 
• Deposition Author(s): Lovejoy, B., Choe, S., Cascio, D., Mcrorie, D.K., Degrado, W., Eisenberg, D.

---

Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 2.10 Å
• R-Value Work: 
  0.180 (Depositor), 0.190 (DCC) 

Literature

Crystal structure of a synthetic triple-stranded alpha-helical bundle.

Lovejoy, B., Choe, S., Cascio, D., McRorie, D.K., DeGrado, W.F., Eisenberg, D.

(1993) Science 259: 1288-1293

• PubMed: 8446897 
• DOI: https://doi.org/10.1126/science.8446897
• Primary Citation of Related Structures:  
  1COS


• PubMed Abstract: 
  

  The x-ray crystal structure of a peptide designed to form a double-stranded parallel coiled coil shows that it is actually a triple-stranded coiled coil formed by three alpha-helices. Unlike the designed parallel coiled coil, the helices run up-up-down. The structure is stabilized by a distinctive hydrophobic interface consisting of eight layers. As in the design, each alpha-helix in the coiled coil contributes one leucine side chain to each layer. The structure suggests that hydrophobic interactions are a dominant factor in the stabilization of coiled coils. The stoichiometry and geometry of coiled coils are primarily determined by side chain packing in the solvent-inaccessible interior, but electrostatic interactions also contribute.

---

Organizational Affiliation: 

Molecular Biology Institute, University of California, Los Angeles 90024-1570.

Biological Assembly 1  

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Homo 3-mer - A3 

Biological assembly 1 assigned by authors and generated by PISA (software)

Macromolecule Content

• Total Structure Weight: 10.01 kDa 
• Atom Count: 741 
• Modelled Residue Count: 93 
• Deposited Residue Count: 93 
• Unique protein chains: 1

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
COILED SERINE	A, B, C	31	N/A	Mutation(s): 0

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 2.10 Å
• R-Value Work:  0.180 (Depositor), 0.190 (DCC) 

Space Group: P 2₁ 2₁ 2₁

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 27.7	α = 90
b = 38.7	β = 90
c = 77.8	γ = 90

Software Package:

Software Name	Purpose
X-PLOR	model building
TNT	refinement
X-PLOR	refinement
X-PLOR	phasing

Structure Validation

Entry History 

Deposition Data

• Released Date: 1993-10-31 
Deposition Author(s): Lovejoy, B., Choe, S., Cascio, D., Mcrorie, D.K., Degrado, W., Eisenberg, D.

Revision History  

• Version 1.0: 1993-10-31
  Type: Initial release
  
• Version 1.1: 2008-03-24
  Changes: Version format compliance
• Version 1.2: 2011-07-13
  Changes: Version format compliance
• Version 1.3: 2019-07-17
  Changes: Data collection, Derived calculations, Other, Refinement description
• Version 1.4: 2019-08-14
  Changes: Data collection, Refinement description
• Version 1.5: 2024-11-06
  Changes: Data collection, Database references, Derived calculations, Structure summary