Inhibitor coordination interactions in the binuclear manganese cluster of arginase

Biochemistry. 2004 Jul 20;43(28):8987-99. doi: 10.1021/bi0491705.


Arginase is a manganese metalloenzyme that catalyzes the hydrolysis of L-arginine to form L-ornithine and urea. The structure and stability of the binuclear manganese cluster are critical for catalytic activity as it activates the catalytic nucleophile, metal-bridging hydroxide ion, and stabilizes the tetrahedral intermediate and its flanking states. Here, we report X-ray structures of a series of inhibitors bound to the active site of arginase, and each inhibitor exploits a different mode of coordination with the Mn(2+)(2) cluster. Specifically, we have studied the binding of fluoride ion (F(-); an uncompetitive inhibitor) and L-arginine, L-valine, dinor-N(omega)-hydroxy-L-arginine, descarboxy-nor-N(omega)-hydroxy-L-arginine, and dehydro-2(S)-amino-6-boronohexanoic acid. Some inhibitors, such as fluoride ion, dinor-N(omega)-hydroxy-L-arginine, and dehydro-2(S)-amino-6-boronohexanoic acid, cause the net addition of one ligand to the Mn(2+)(2) cluster. Other inhibitors, such as descarboxy-nor-N(omega)-hydroxy-L-arginine, simply displace the metal-bridging hydroxide ion of the native enzyme and do not cause any net change in the metal coordination polyhedra. The highest affinity inhibitors displace the metal-bridging hydroxide ion (and sometimes occupy a Mn(2+)(A) site found vacant in the native enzyme) and maintain a conserved array of hydrogen bonds with their alpha-amino and -carboxylate groups.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Arginase / antagonists & inhibitors
  • Arginase / chemistry*
  • Arginine / analogs & derivatives
  • Arginine / chemistry
  • Binding Sites
  • Crystallography, X-Ray
  • Enzyme Inhibitors / chemistry*
  • Fluorine / chemistry
  • Hydrogen Bonding
  • Manganese*
  • Metalloproteins / antagonists & inhibitors
  • Metalloproteins / chemistry
  • Molecular Structure
  • Protein Binding
  • Rats
  • Recombinant Proteins
  • Valine / chemistry


  • Enzyme Inhibitors
  • Metalloproteins
  • Recombinant Proteins
  • Fluorine
  • Manganese
  • Arginine
  • Arginase
  • Valine

Associated data

  • PDB/1T4P
  • PDB/1T4R
  • PDB/1T4S
  • PDB/1T4T
  • PDB/1T5G