2SNM

IN A STAPHYLOCOCCAL NUCLEASE MUTANT THE SIDE-CHAIN of A LYSINE REPLACING VALINE 66 IS FULLY BURIED IN THE HYDROPHOBIC CORE


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.97 Å

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history

Literature

In a staphylococcal nuclease mutant the side-chain of a lysine replacing valine 66 is fully buried in the hydrophobic core.

Stites, W.E.Gittis, A.G.Lattman, E.E.Shortle, D.

(1991) J.Mol.Biol. 221: 7-14


  • PubMed Abstract: 
  • The crystal structure of the staphylococcal nuclease mutant V66K, in which valine 66 is replaced by lysine, has been solved at 1.97 A resolution. Unlike lysine residues in previously reported protein structures, this residue appears to bury its side- ...

    The crystal structure of the staphylococcal nuclease mutant V66K, in which valine 66 is replaced by lysine, has been solved at 1.97 A resolution. Unlike lysine residues in previously reported protein structures, this residue appears to bury its side-chain in the hydrophobic core without salt bridging, hydrogen bonding or other forms of electrostatic stabilization. Solution studies of the free energy of denaturation, delta GH2O, show marked pH dependence and clearly indicate that the lysine residue must be deprotonated in the folded state. V66K is highly unstable at neutral pH but only modestly less stable than the wild-type protein at high pH. The pH dependence of stability for V66K, in combination with similar measurements for the wild-type protein, allowed determination of the pKa values of the lysine in both the denatured and native forms. The epsilon-amine of this residue has a pKa value in the denatured state of 10.2, but in the native state it must be 6.4 or lower. The epsilon-amine is thus deprotonated in the folded molecule. These values enabled an estimation of the epsilon-amine's relative change in free energy of solvation between solvent and the protein interior at 5.1 kcal/mol or greater. This implies that the value of the dielectric constant of the protein interior must be less than 12.8. Lysine is usually found with the methylene groups of its side-chain partly buried but is nevertheless considered a hydrophilic surface residue. It would appear that the high pKa value of lysine, which gives it a positive charge at physiological pH, is the primary reason for its almost exclusive confinement to the surface proteins. When deprotonated, this amino acid type can be fully incorporated into the hydrophobic core.


    Organizational Affiliation

    Department of Biological Chemistry, School of Medicine, Johns Hopkins University, Baltimore, MD 21205.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
STAPHYLOCOCCAL NUCLEASE
A
149Staphylococcus aureusGene Names: nuc
EC: 3.1.31.1
Find proteins for P00644 (Staphylococcus aureus)
Go to UniProtKB:  P00644
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
CA
Query on CA

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Download CCD File 
A
CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
THP
Query on THP

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Download CCD File 
A
THYMIDINE-3',5'-DIPHOSPHATE
C10 H16 N2 O11 P2
CSNCBOPUCJOHLS-XLPZGREQSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.97 Å
  • Space Group: P 41
Unit Cell:
Length (Å)Angle (°)
a = 47.156α = 90.00
b = 47.156β = 90.00
c = 62.020γ = 90.00
Software Package:
Software NamePurpose
X-PLORmodel building
X-PLORrefinement
X-PLORphasing
PROLSQrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 1993-01-15
    Type: Initial release
  • Version 1.1: 2008-03-25
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance
  • Version 1.3: 2014-05-21
    Type: Version format compliance