Alpha1-antichymotrypsin serpin in the delta conformation (partial loop insertion)

Experimental Data Snapshot

  • Resolution: 2.27 Å
  • R-Value Free: 0.243 
  • R-Value Work: 0.197 
  • R-Value Observed: 0.197 

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This is version 1.3 of the entry. See complete history


Inactive Conformation of the Serpin Alpha1-Antichymotrypsin Indicates Two-Stage Insertion of the Reactive Loop: Implications for Inhibitory Function and Conformational Disease

Gooptu, B.Hazes, B.Chang, W.-S.W.Dafforn, T.R.Carrell, R.W.Read, R.J.Lomas, D.A.

(2000) Proc Natl Acad Sci U S A 97: 67

  • DOI: https://doi.org/10.1073/pnas.97.1.67
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    The serpins are a family of proteinase inhibitors that play a central role in the control of proteolytic cascades. Their inhibitory mechanism depends on the intramolecular insertion of the reactive loop into beta-sheet A after cleavage by the target proteinase. Point mutations within the protein can allow aberrant conformational transitions characterized by beta-strand exchange between the reactive loop of one molecule and beta-sheet A of another. These loop-sheet polymers result in diseases as varied as cirrhosis, emphysema, angio-oedema, and thrombosis, and we recently have shown that they underlie an early-onset dementia. We report here the biochemical characteristics and crystal structure of a naturally occurring variant (Leu-55-Pro) of the plasma serpin alpha(1)-antichymotrypsin trapped as an inactive intermediate. The structure demonstrates a serpin configuration with partial insertion of the reactive loop into beta-sheet A. The lower part of the sheet is filled by the last turn of F-helix and the loop that links it to s3A. This conformation matches that of proposed intermediates on the pathway to complex and polymer formation in the serpins. In particular, this intermediate, along with the latent and polymerized conformations, explains the loss of activity of plasma alpha(1)-antichymotrypsin associated with chronic obstructive pulmonary disease in patients with the Leu-55-Pro mutation.

  • Organizational Affiliation

    Respiratory Medicine Unit, Department of Medicine University of Cambridge, United Kingdom.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
ALPHA-1-ANTICHYMOTRYPSIN401Homo sapiensMutation(s): 1 
UniProt & NIH Common Fund Data Resources
Find proteins for P01011 (Homo sapiens)
Explore P01011 
Go to UniProtKB:  P01011
PHAROS:  P01011
GTEx:  ENSG00000196136 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP01011
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.27 Å
  • R-Value Free: 0.243 
  • R-Value Work: 0.197 
  • R-Value Observed: 0.197 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 41.723α = 90
b = 122.094β = 101.03
c = 41.724γ = 90
Software Package:
Software NamePurpose
MOSFLMdata reduction
SCALAdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2000-01-17
    Type: Initial release
  • Version 1.1: 2012-11-28
    Changes: Database references, Derived calculations, Other, Refinement description, Structure summary, Version format compliance
  • Version 1.2: 2019-05-08
    Changes: Data collection, Experimental preparation, Other
  • Version 1.3: 2023-12-13
    Changes: Data collection, Database references, Other, Refinement description