Biological Assembly 1  

 3D View: Structure | 1D-3D View | Validation Report | Ligand Interaction

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Hetero 2-mer - A1B1 

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

Macromolecule Content

• Total Structure Weight: 42.93 kDa 
• Atom Count: 3006 
• Modelled Residue Count: 369 
• Deposited Residue Count: 378 
• Unique protein chains: 2

1AS4

CLEAVED ANTICHYMOTRYPSIN A349R

• PDB DOI: 10.2210/pdb1AS4/pdb

• Classification: SERPIN
• Organism(s): Homo sapiens
• Expression System: Escherichia coli
• Mutation(s): Yes 


• Deposited: 1997-08-12 Released: 1998-02-25 
• Deposition Author(s): Lukacs, C.M., Christianson, D.W.

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 2.10 Å
• R-Value Free: 0.240 
• R-Value Work: 0.198 
• R-Value Observed: 0.198 

Literature

Engineering an anion-binding cavity in antichymotrypsin modulates the "spring-loaded" serpin-protease interaction.

Lukacs, C.M., Rubin, H., Christianson, D.W.

(1998) Biochemistry 37: 3297-3304

• PubMed: 9521649 
• DOI: 10.1021/bi972359e
• Primary Citation of Related Structures:  
  1AS4, 3CAA, 4CAA


• PubMed Abstract: 
  

Expressed in a kinetically trapped folding state, a serpin couples the thermodynamic driving force of a massive beta-sheet rearrangement to the inhibition of a target protease. Hence, the serpin-protease interaction is the premier example of a "spring-loaded" protein-protein interaction. Amino acid substitutions in the hinge region of a serpin reactive loop can weaken the molecular spring, which converts the serpin from an inhibitor into a substrate. To probe the molecular basis of this conversion, we report the crystal structure of A349R antichymotrypsin in the reactive loop cleaved state at 2.1 A resolution. This amino acid substitution does not block the beta-sheet rearrangement despite the burial of R349 in the hydrophobic core of the cleaved serpin along with a salt-linked acetate ion. The inhibitory activity of this serpin variant is not obliterated; remarkably, its inhibitory properties are anion-dependent due to the creation of an anion-binding cavity in the cleaved serpin.

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Related Citations: 

• Arginine Substitutions in the Hinge Region of Antichymotrypsin Affect Serpin Beta-Sheet Rearrangement
  Lukacs, C.M., Zhong, J.Q., Plotnick, M.I., Rubin, H., Cooperman, B.S., Christianson, D.W.
  (1996) Nat Struct Biol 3: 888

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Organizational Affiliation: 

Department of Chemistry, University of Pennsylvania, Philadelphia 19104, USA.

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
ANTICHYMOTRYPSIN	A	341	Homo sapiens	Mutation(s): 1  Gene Names: ACT, SERPINA3, AACT, GIG24, GIG25
UniProt & NIH Common Fund Data Resources
Find proteins for P01011 (Homo sapiens) Explore P01011  Go to UniProtKB:  P01011
PHAROS:  P01011

Entity ID: 2
Molecule	Chains	Sequence Length	Organism	Details	Image
ANTICHYMOTRYPSIN	B	37	Homo sapiens	Mutation(s): 0  Gene Names: ACT, SERPINA3, AACT, GIG24, GIG25
UniProt & NIH Common Fund Data Resources
Find proteins for P01011 (Homo sapiens) Explore P01011  Go to UniProtKB:  P01011
PHAROS:  P01011

Small Molecules

Ligands 1 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
ACT	C [auth B]	ACETATE ION C2 H3 O2 QTBSBXVTEAMEQO-UHFFFAOYSA-M

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 2.10 Å
• R-Value Free: 0.240 
• R-Value Work: 0.198 
• R-Value Observed: 0.198 
• Space Group: P 2₁ 2₁ 2₁

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 71.7	α = 90
b = 78.35	β = 90
c = 79.23	γ = 90

Software Package:

Software Name	Purpose
X-PLOR	model building
X-PLOR	refinement
MOSFLM	data reduction
CCP4	data scaling
X-PLOR	phasing

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 1997-08-12 
• Released Date: 1998-02-25 
Deposition Author(s): Lukacs, C.M., Christianson, D.W.

Revision History  

• Version 1.0: 1998-02-25
  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: 2021-11-03
  Changes: Database references, Derived calculations, Other