5MON

Joint X-ray/neutron structure of cationic trypsin in complex with 2-aminopyridine

Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 0.94 Å
  • R-Value Free: 0.104 
  • R-Value Work: 0.099 
  • R-Value Observed: 0.099 
  • Method: NEUTRON DIFFRACTION
  • Resolution: 1.42 Å
  • R-Value Free: 0.181 
  • R-Value Work: 0.170 
  • R-Value Observed: 0.171 

wwPDB Validation   3D Report Full Report


This is version 2.1 of the entry. See complete history. 


Literature

Charges Shift Protonation: Neutron Diffraction Reveals that Aniline and 2-Aminopyridine Become Protonated Upon Binding to Trypsin.

Schiebel, J., Gaspari, R., Sandner, A., Ngo, K., Gerber, H.D., Cavalli, A., Ostermann, A., Heine, A., Klebe, G.

(2017) Angew Chem Int Ed Engl 56: 4887-4890

  • DOI: 10.1002/anie.201701038
  • Primary Citation of Related Structures:  
    5MN1, 5MNA, 5MNB, 5MNC, 5MNX, 5MNY, 5MON, 5MOO

  • PubMed Abstract: 

    • Hydrogen atoms play a key role in protein-ligand recognition. They determine the quality of established H-bonding networks and define the protonation of bound ligands. Structural visualization of H atoms by X-ray crystallography is rarely possible. We used neutron diffraction to determine the positions of the hydrogen atoms in the ligands aniline and 2-aminopyridine bound to the archetypical serine protease trypsin ...

    Hydrogen atoms play a key role in protein-ligand recognition. They determine the quality of established H-bonding networks and define the protonation of bound ligands. Structural visualization of H atoms by X-ray crystallography is rarely possible. We used neutron diffraction to determine the positions of the hydrogen atoms in the ligands aniline and 2-aminopyridine bound to the archetypical serine protease trypsin. The resulting structures show the best resolution so far achieved for proteins larger than 100 residues and allow an accurate description of the protonation states and interactions with nearby water molecules. Despite its low pK a of 4.6 and a large distance of 3.6 Å to the charged Asp189 at the bottom of the S1 pocket, the amino group of aniline becomes protonated, whereas in 2-aminopyridine, the pyridine nitrogen picks up the proton although its amino group is 1.6 Å closer to Asp189. Therefore, apart from charge-charge distances, tautomer stability is decisive for the resulting binding poses, an aspect that is pivotal for predicting correct binding.

    Organizational Affiliation: 

    Institut für Pharmazeutische Chemie, Philipps-Universität Marburg, Marbacher Weg 6, 35032, Marburg, Germany.



Macromolecules
Find similar proteins by: 
(by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Cationic trypsinA223Bos taurusMutation(s): 0 
EC: 3.4.21.4
UniProt
Find proteins for P00760 (Bos taurus)
Explore P00760 
Go to UniProtKB:  P00760
Protein Feature View
Expand
  • Reference Sequence
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
SO4
Query on SO4
Download Ideal Coordinates CCD File 
D [auth A]SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L		 Ligand Interaction
2AP
Query on 2AP
Download Ideal Coordinates CCD File 
C [auth A]2-AMINOPYRIDINE
C5 H7 N2
ICSNLGPSRYBMBD-UHFFFAOYSA-O		 Ligand Interaction
CA
Query on CA
Download Ideal Coordinates CCD File 
B [auth A]CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N		 Ligand Interaction
Binding Affinity Annotations 
IDSourceBinding Affinity
2AP Binding MOAD:  5MON Kd: 3.30e+6 (nM) from 1 assay(s)
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 0.94 Å
  • R-Value Free: 0.104 
  • R-Value Work: 0.099 
  • R-Value Observed: 0.099 
  • Space Group: P 21 21 21
  • Method: NEUTRON DIFFRACTION
  • Resolution: 1.42 Å
  • R-Value Free: 0.181 
  • R-Value Work: 0.170 
  • R-Value Observed: 0.171 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 54.989α = 90
b = 58.537β = 90
c = 67.618γ = 90
Software Package:
Software NamePurpose
PHENIXrefinement
XDSdata reduction
HKL-2000data reduction
XDSdata scaling
HKL-2000data scaling
PHASERphasing
Cootmodel building

Structure Validation

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View more in-depth experimental data

Entry History & Funding Information

Deposition Data

Funding OrganizationLocationGrant Number
European Research Council268145-DrugProfilBind

Revision History  (Full details and data files)

  • Version 1.0: 2017-05-24
    Type: Initial release
  • Version 2.0: 2017-08-23
    Changes: Atomic model, Data collection, Structure summary
  • Version 2.1: 2018-11-14
    Changes: Data collection