Novel method of protein purification for structural research. Example of ultra high resolution structure of SPI-2 inhibitor by X-ray and NMR spectroscopy.

Experimental Data Snapshot

  • Method: SOLUTION NMR
  • Conformers Calculated: 200 
  • Conformers Submitted: 17 
  • Selection Criteria: structures with the lowest energy 

wwPDB Validation   3D Report Full Report

This is version 1.2 of the entry. See complete history


Atomic resolution structure of a protein prepared by non-enzymatic His-tag removal. Crystallographic and NMR study of GmSPI-2 inhibitor.

Kopera, E.Bal, W.Lenarcic Zivkovic, M.Dvornyk, A.Kludkiewicz, B.Grzelak, K.Zhukov, I.Zagorski-Ostoja, W.Jaskolski, M.Krzywda, S.

(2014) PLoS One 9: e106936-e106936

  • DOI: https://doi.org/10.1371/journal.pone.0106936
  • Primary Citation of Related Structures:  
    2M5X, 4HGU

  • PubMed Abstract: 

    Purification of suitable quantity of homogenous protein is very often the bottleneck in protein structural studies. Overexpression of a desired gene and attachment of enzymatically cleavable affinity tags to the protein of interest made a breakthrough in this field. Here we describe the structure of Galleria mellonella silk proteinase inhibitor 2 (GmSPI-2) determined both by X-ray diffraction and NMR spectroscopy methods. GmSPI-2 was purified using a new method consisting in non-enzymatic His-tag removal based on a highly specific peptide bond cleavage reaction assisted by Ni(II) ions. The X-ray crystal structure of GmSPI-2 was refined against diffraction data extending to 0.98 Å resolution measured at 100 K using synchrotron radiation. Anisotropic refinement with the removal of stereochemical restraints for the well-ordered parts of the structure converged with R factor of 10.57% and Rfree of 12.91%. The 3D structure of GmSPI-2 protein in solution was solved on the basis of 503 distance constraints, 10 hydrogen bonds and 26 torsion angle restraints. It exhibits good geometry and side-chain packing parameters. The models of the protein structure obtained by X-ray diffraction and NMR spectroscopy are very similar to each other and reveal the same β2αβ fold characteristic for Kazal-family serine proteinase inhibitors.

  • Organizational Affiliation

    Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland; NanoBioMedical Centre, A. Mickiewicz University, Poznan, Poland.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Silk protease inhibitor 240Galleria mellonellaMutation(s): 0 
Find proteins for Q968S7 (Galleria mellonella)
Explore Q968S7 
Go to UniProtKB:  Q968S7
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ968S7
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: SOLUTION NMR
  • Conformers Calculated: 200 
  • Conformers Submitted: 17 
  • Selection Criteria: structures with the lowest energy 

Structure Validation

View Full Validation Report

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2014-03-12
    Type: Initial release
  • Version 1.1: 2015-02-25
    Changes: Database references
  • Version 1.2: 2023-06-14
    Changes: Database references, Other