1RNQ

RIBONUCLEASE A CRYSTALLIZED FROM 8M SODIUM FORMATE


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Work: 0.161 
  • R-Value Observed: 0.161 

wwPDB Validation   3D Report Full Report


This is version 1.4 of the entry. See complete history


Literature

Ionic interactions in crystalline bovine pancreatic ribonuclease A.

Fedorov, A.A.Joseph-McCarthy, D.Fedorov, E.Sirakova, D.Graf, I.Almo, S.C.

(1996) Biochemistry 35: 15962-15979

  • DOI: https://doi.org/10.1021/bi961533g
  • Primary Citation of Related Structures:  
    1RNO, 1RNQ, 1RNW, 1RNX, 1RNY, 1RNZ

  • PubMed Abstract: 

    Isomorphous crystals (space group P3(2)21) of bovine pancreatic ribonuclease A (RNase A) were prepared at a pH of 5.5 in a series of high salt conditions, where both the nature of the ions and the ionic strength varied: 80% ammonium sulfate (mu = 12.5); 8 M sodium formate (mu = 8.0); 3 M NaCl, 30% ammonium sulfate (mu = 7.0); 3 M CsCl, 30% ammonium sulfate (mu = 7.0); and 2.5 M NaCl, 3.3 M sodium formate (mu = 5.8). These structures were independently refined to a resolution of 2.0 A or better with R-factors that range from 16.1% to 17.5%. A comparison of these six structures and the monoclinic crystal form of RNase A grown from alcohol shows that changes in ionic strength do not alter the secondary or tertiary structure and that there are no significant changes in intramolecular salt bridges. These findings support the notion that structures determined from crystals grown in high salt are representative of the overall structural and electrostatic features present under physiological conditions. While little effect was observed on the main chain conformation, several residues adopted different side chain conformations and altered hydrogen-bonding patterns, either as result of direct anion binding or more subtle indirect effects. Changes in the ionic composition of the mother liquor allowed for the occupancy of the active site with different anions. The direct observation of active site-bound chloride and formate anions supports the proposal that these species act as true competitive inhibitors of RNase A and not through nonspecific electrostatic effects. The identification of bound formate anions allowed for an experimental validation of computational-based functional group mapping techniques and suggests a useful modification to these approaches. Electrostatic surface potential calculations identify a nearly continuous band of positive potential, consistent with an extended binding site for polynucleotide ligands and substrates. The majority of these residues are not involved in salt bridges, which may facilitate binding to extended polynucleotide substrates. Selection of the appropriate solvent conditions results in an unoccupied active site, which will allow this crystal form to be used for the crystallographic study of productive ligand-binding modes.


  • Organizational Affiliation

    Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, USA.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
RIBONUCLEASE A124Bos taurusMutation(s): 0 
EC: 3.1.27.5
UniProt
Find proteins for P61823 (Bos taurus)
Explore P61823 
Go to UniProtKB:  P61823
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP61823
Sequence Annotations
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  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
FMT
Query on FMT

Download Ideal Coordinates CCD File 
B [auth A],
C [auth A]
FORMIC ACID
C H2 O2
BDAGIHXWWSANSR-UHFFFAOYSA-N
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Work: 0.161 
  • R-Value Observed: 0.161 
  • Space Group: P 32 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 64.936α = 90
b = 64.936β = 90
c = 65.289γ = 120
Software Package:
Software NamePurpose
XDSdata scaling
X-PLORmodel building
PROFFTrefinement
X-PLORrefinement
XDSdata reduction
X-PLORphasing

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1996-04-03
    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: 2019-07-17
    Changes: Data collection, Refinement description
  • Version 1.4: 2019-08-14
    Changes: Data collection, Refinement description