Experimental Data Snapshot

  • Resolution: 2.60 Å
  • R-Value Work: 0.166 
  • R-Value Observed: 0.166 

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Escherichia coli alkaline phosphatase: X-ray structural studies of a mutant enzyme (His-412-->Asn) at one of the catalytically important zinc binding sites.

Ma, L.Tibbitts, T.T.Kantrowitz, E.R.

(1995) Protein Sci 4: 1498-1506

  • DOI: https://doi.org/10.1002/pro.5560040807
  • Primary Citation of Related Structures:  
    1ALI, 1ALJ

  • PubMed Abstract: 

    The X-ray structure of a mutant version of Escherichia coli alkaline phosphatase (H412N) in which His-412 was replaced by Asn has been determined at both low (-Zn) and high (+Zn) concentrations of zinc. In the wild-type structure, His-412 is a direct ligand to one of the two catalytically critical zinc atoms (Zn1) in the active site. Characterization of the H412N enzyme in solution revealed that the mutant enzyme required high concentrations of zinc for maximal activity and for high substrate and phosphate affinity (Ma L, Kantrowitz ER, 1994, J Biol Chem 269:31614-31619). The H412N enzyme was also inhibited by Tris, in contrast to the wild-type enzyme, which is activated more than twofold by 1 M Tris. To understand these kinetic properties at the molecular level, the structure of the H412N (+Zn) enzyme was refined to an R-factor of 0.174 at 2.2 A resolution, and the structure of the H412N(-Zn) enzyme was refined to an R-factor of 0.166 at a resolution of 2.6 A. Both indicated that the Asn residue substituted for His-412 did not coordinate well to Zn1. In the H412N(-Zn) structure, the Zn1 site had very low occupancy and the phosphate was shifted by 1.8 A from its position in the wild-type structure. The Mg binding site was also affected by the substitution of Asn for His-412. Both structures of the H412N enzyme also revealed a surface-accessible cavity near the Zn1 site that may serve as a binding site for Tris.(ABSTRACT TRUNCATED AT 250 WORDS)

  • Organizational Affiliation

    Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02167, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
A, B
449Escherichia coliMutation(s): 1 
Gene Names: PHOA
Find proteins for P00634 (Escherichia coli (strain K12))
Explore P00634 
Go to UniProtKB:  P00634
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP00634
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.60 Å
  • R-Value Work: 0.166 
  • R-Value Observed: 0.166 
  • Space Group: I 2 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 194.76α = 90
b = 167.74β = 90
c = 76.23γ = 90
Software Package:
Software NamePurpose
ADSCdata collection
X-PLORmodel building

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1995-11-14
    Type: Initial release
  • Version 1.1: 2008-03-03
    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