8EST

REACTION OF PORCINE PANCREATIC ELASTASE WITH 7-SUBSTITUTED 3-ALKOXY-4-CHLOROISOCOUMARINS: DESIGN OF POTENT INHIBITORS USING THE CRYSTAL STRUCTURE OF THE COMPLEX FORMED WITH 4-CHLORO-3-ETHOXY-7-GUANIDINO-ISOCOUMARIN


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.78 Å
  • R-Value Work: 0.170 

wwPDB Validation   3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

Reaction of porcine pancreatic elastase with 7-substituted 3-alkoxy-4-chloroisocoumarins: design of potent inhibitors using the crystal structure of the complex formed with 4-chloro-3-ethoxy-7-guanidinoisocoumarin.

Powers, J.C.Oleksyszyn, J.Narasimhan, S.L.Kam, C.M.

(1990) Biochemistry 29: 3108-3118

  • DOI: 10.1021/bi00464a030
  • Primary Citation of Related Structures:  
    8EST

  • PubMed Abstract: 
  • The crystal structure of the acyl enzyme formed upon inhibition of porcine pancreatic elastase (PPE) by 4-chloro-3-ethoxy-7-guanidinoisocoumarin has been determined at a 1.85-A effective resolution. The chlorine atom is still present in this acyl enzyme, in contrast to the previously reported structure of the 7-amino-4-chloro-3-methoxyisocoumarin-PPE complex where the chlorine atom has been replaced by an acetoxy group ...

    The crystal structure of the acyl enzyme formed upon inhibition of porcine pancreatic elastase (PPE) by 4-chloro-3-ethoxy-7-guanidinoisocoumarin has been determined at a 1.85-A effective resolution. The chlorine atom is still present in this acyl enzyme, in contrast to the previously reported structure of the 7-amino-4-chloro-3-methoxyisocoumarin-PPE complex where the chlorine atom has been replaced by an acetoxy group. The guanidino group forms hydrogen bonds with the carbonyl group and side-chain hydroxyl group of Thr-41, and the acyl carbonyl group has been twisted out of the oxyanion hole. Molecular modeling indicates that the orientation of the initial Michaelis enzyme-inhibitor complex is quite different from that of the acyl enzyme since simple reconstruction of the isocoumarin ring would result in unfavorable interactions with Ser-195 and His-57. Molecular models were used to design a series of new 7-(alkylureido)- and 7-(alkylthioureido)-substituted derivatives of 3-alkoxy-7-amino-4-chloroisocoumarin as PPE inhibitors. All the 3-ethoxyisocoumarins were better inhibitors than those in the 3-methoxy series due to better interactions with the S1 pocket of PPE. The best ureido inhibitor also contained a tert-butylureido group at the 7-position of the isocoumarin. Due to a predicted interaction with a small hydrophobic pocket on the surface of PPE, this isocoumarin and a related phenylthioureido derivative are among the best irreversible inhibitors thus far reported for PPE (kobs/[I] = 8100 M-1 s-1 and 12,000 M-1 s-1). Kinetic studies of the stability of enzyme-inhibitor complexes suggest that many isocoumarins are alkylating the active site histidine at pH 7.5 via a quinone imine methide intermediate, while at pH 5.0, the predominant pathway appears to be simple formation of a stable acyl enzyme derivative.


    Related Citations: 
    • Effect of the 7-Amino Substituent on the Inhibitory Potency of Mechanism-Based Isocoumarin Inhibitors for Porcine Pancreatic and Human Neutrophil Elastases: A 1.85-Angstroms X-Ray Structure of the Complex between Porcine Pancreatic Elastase and 7-[(N-Tosylphenylalanyl)Amino]-4-Chloro-3-Methoxyisocoumarin
      Hernandez, M.A., Powers, J.C., Glinski, J., Oleksyszyn, J., Vijayalakshmi, J., Meyerjunior, E.F.
      (1992) J Med Chem 35: 1121
    • Structural Study of Porcine Pancreatic Elastase Complexed with 7-Amino-3-(2-Bromoethoxy)-4-Chloroisocoumarin as a Nonreactivatable Doubly Covalent Enzyme-Inhibitor Complex
      Vijayalakshmi, J., Meyerjunior, E.F., Kam, C.-M., Powers, J.C.
      (1991) Biochemistry 30: 2175
    • The 2.2-Angstrom Resolution X-Ray Crystal Structure of the Complex of Trypsin Inhibited by 4-Chloro-3-Ethoxy-7-Guanidinoisocoumarin: A Proposed Model of the Thrombin-Inhibitor Complex
      Chow, M.M., Meyerjunior, E.F., Bode, W., Kam, C.-M., Radhakrishnan, R., Vijayalakshmi, J., Powers, J.C.
      (1990) J Am Chem Soc 112: 7783
    • Human Leukocyte and Porcine Pancreatic Elastase: X-Ray Crystal Structures, Mechanism, Substrate Specificity, and Mechanism-Based Inhibitors
      Bode, W., Meyerjunior, E.F., Powers, J.C.
      (1989) Biochemistry 28: 1951
    • Crystal Structures of the Complex of Porcine Pancreatic Elastase with Two Valine-Derived Benzoxazinone Inhibitors
      Radhakrishnan, R., Presta, L.G., Meyerjunior, E.F., Wildonger, R.
      (1987) J Mol Biol 198: 417
    • Stereospecific Reaction of 3-Methoxy-4-Chloro-7-Amino-Isocoumarin with Crystalline Porcine Pancreatic Elastase
      Meyerjunior, E.F., Presta, L.G., Radhakrishnan, R.
      (1985) J Am Chem Soc 107: 4091

    Organizational Affiliation

    School of Chemistry, Georgia Institute of Technology, Atlanta 30332.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
PORCINE PANCREATIC ELASTASEA [auth E]240Sus scrofaMutation(s): 0 
Gene Names: CELA1ELA1
EC: 3.4.21.36
UniProt
Find proteins for P00772 (Sus scrofa)
Explore P00772 
Go to UniProtKB:  P00772
Protein Feature View
Expand
  • Reference Sequence
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
GIS (Subject of Investigation/LOI)
Query on GIS

Download Ideal Coordinates CCD File 
D [auth E]ETHYL-(2-CARBOXY-4-GUANIDINIUM-PHENYL)-CHLOROACETATE
C12 H14 Cl N3 O4
HIYFNBISGUASFH-VIFPVBQESA-N
 Ligand Interaction
SO4
Query on SO4

Download Ideal Coordinates CCD File 
B [auth E]SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
 Ligand Interaction
CA
Query on CA

Download Ideal Coordinates CCD File 
C [auth E]CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.78 Å
  • R-Value Work: 0.170 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 50.62α = 90
b = 58.26β = 90
c = 75.24γ = 90
Software Package:
Software NamePurpose
EREFrefinement

Structure Validation

View Full Validation Report




Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1992-10-15
    Type: Initial release
  • Version 1.1: 2008-03-03
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance