1T5F: Arginase I-Aoh Complex

Arginase is a binuclear manganese metalloenzyme that catalyzes the hydrolysis of l-arginine to form l-ornithine and urea. Chiral L-amino acids bearing aldehyde side chains have been synthesized in which the electrophilic aldehyde C=O bond is isosteric with the C=N bond of L-arginine. This substitution is intended to facilitate nucleophilic attack by the metal-bridging hydroxide ion upon binding to the arginase active site. Syntheses of the amino acid aldehydes have been accomplished by reduction, oxidation, and Wittig-type reaction with a commercially available derivative of L-glutamic acid. Amino acid aldehydes exhibit inhibition in the micromolar range, and the X-ray crystal structure of arginase I complexed with one of these inhibitors, (S)-2-amino-7-oxoheptanoic acid, has been determined at 2.2 A resolution. In the enzyme-inhibitor complex, the inhibitor aldehyde moiety is hydrated to form the gem-diol: one hydroxyl group bridges the Mn(2+)(2) cluster and donates a hydrogen bond to D128, and the second hydroxyl group donates a hydrogen bond to E277. The binding mode of the neutral gem-diol may mimic the binding of the neutral tetrahedral intermediate and its flanking transition states in arginase catalysis.
PDB ID: 1T5FDownload
MMDB ID: 33310
PDB Deposition Date: 2004/5/4
Updated in MMDB: 2012/11
Experimental Method:
x-ray diffraction
Resolution: 2.2  Å
Source Organism:
Similar Structures:
Biological Unit for 1T5F: trimeric; determined by author and by software (PISA)
Molecular Components in 1T5F
Label Count Molecule
Proteins (3 molecules)
Arginase 1(Gene symbol: Arg1)
Molecule annotation
Chemicals (9 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB