1ATA

HIGH-RESOLUTION STRUCTURE OF ASCARIS TRYPSIN INHIBITOR IN SOLUTION: DIRECT EVIDENCE FOR A PH INDUCED CONFORMATIONAL TRANSITION IN THE REACTIVE SITE


Experimental Data Snapshot

  • Method: SOLUTION NMR
  • Conformers Submitted: 

wwPDB Validation   3D Report Full Report

Currently 1ATA does not have a validation slider image.


This is version 1.4 of the entry. See complete history


Literature

High-resolution structure of Ascaris trypsin inhibitor in solution: direct evidence for a pH-induced conformational transition in the reactive site.

Grasberger, B.L.Clore, G.M.Gronenborn, A.M.

(1994) Structure 2: 669-678

  • DOI: https://doi.org/10.1016/s0969-2126(00)00067-8
  • Primary Citation of Related Structures:  
    1ATA, 1ATB, 1ATD, 1ATE

  • PubMed Abstract: 

    The Ascaris trypsin inhibitor (ATI) is a member of a new family of serine protease inhibitors isolated from the helminthic worm Ascaris lumbricoides var suum. This family comprises five chymotrypsin/elastase inhibitors and one trypsin inhibitor. Members are characterized by the presence of five disulfide bonds (two of which are located on either side of the reactive site) in a single small protein domain of 61-62 residues. The solution structure of ATI has been determined at pH 2.4 and pH 4.75 by NMR spectroscopy. Iterative refinement permitted the unambiguous assignment of the pairing of the five disulfide bridges (Cys5-Cys38, Cys15-Cys33, Cys18-Cys29, Cys22-Cys60, and Cys40-Cys54) which were previously unknown. The structure includes four short beta-strands arranged in two approximately perpendicular beta-sheets. The reactive site loop is bounded by two disulfide bridges (Cys15-Cys33 and Cys18-Cys29) and is part of the long loop (residues 15-25) connecting strands beta 1 and beta 2. Comparison of the nuclear Overhauser enhancement data at the two pH values revealed significant differences centered around the reactive site. While the reactive site at pH 2.4 closely resembles that of other protease inhibitors, at pH 4.75 the reactive site loop undergoes a major conformational rearrangement involving the psi backbone torsion angles of the P2, P1 and P1' residues (residues 30-32). This is associated with a change in the positions of the side chains of Arg31 and Glu32. The overall three-dimensional structure of ATI posesses an unusual fold and, with the exception of the reactive site, shows no similarity to other serine protease inhibitors. The observation that the reactive site of the low pH form of ATI is similar to that of other serine proteases suggests that this is the active form of the protein.


  • Organizational Affiliation

    Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
ASCARIS TRYPSIN INHIBITOR62Ascaris suumMutation(s): 0 
UniProt
Find proteins for P19398 (Ascaris suum)
Explore P19398 
Go to UniProtKB:  P19398
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP19398
Sequence Annotations
Expand
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: SOLUTION NMR
  • Conformers Submitted: 

Structure Validation

View Full Validation Report

Currently 1ATA does not have a validation slider image.



Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1994-08-31
    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: 2022-02-16
    Changes: Database references, Derived calculations, Other
  • Version 1.4: 2024-10-30
    Changes: Data collection, Structure summary