PDBsum entry 1fb5

Transferase

PDB id: 1fb5

Contents

Protein chain

320 a.a. *

Ligands

NVA

Waters ×3

* Residue conservation analysis

PDB id:

1fb5

Name:

Transferase

Title:

Low resolution structure of ovine ornithine transcarbmoylase in the unliganded state

Structure:

Ornithine transcarbamoylase. Chain: a. Synonym: otcase. Ec: 2.1.3.3

Source:

Ovis aries. Sheep. Organism_taxid: 9940. Organ: liver

Biol. unit:

Trimer (from PDB file)

Resolution:

3.50Å R-factor: 0.212 R-free: 0.252

Authors:

G.Zanotti,R.Battistutta,M.Panzalorto,P.Francescato,G.Bruno,A.De Gregorio

Key ref:

A.De Gregorio et al. (2003). Functional and structural characterization of ovine ornithine transcarbamoylase. Org Biomol Chem, 1, 3178-3185. PubMed id: 14527149

Date:

14-Jul-00 Release date: 26-Aug-03

Protein chain

P84010  (OTC_SHEEP) -  Ornithine transcarbamylase, mitochondrial from Ovis aries

Seq: 355 a.a.

Struc: 320 a.a.*

* PDB and UniProt seqs differ at 18 residue positions (black crosses)

Enzyme reactions

• Enzyme class: E.C.2.1.3.3 - ornithine carbamoyltransferase.
• Pathway: Urea Cycle and Arginine Biosynthesis
• Reaction: carbamoyl phosphate + L-ornithine = L-citrulline + phosphate + H⁺

carbamoyl phosphate + L-ornithine (Bound ligand (Het Group name = NVA) matches with 88.89% similarity) = L-citrulline + phosphate + H(+)

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

reference

Org Biomol Chem 1:3178-3185 (2003)

PubMed id: 14527149

Functional and structural characterization of ovine ornithine transcarbamoylase.

A.De Gregorio, R.Battistutta, N.Arena, M.Panzalorto, P.Francescato, G.Valentini, G.Bruno, G.Zanotti.

ABSTRACT

Ornithine transcarbamoylase from ovine liver has been purified to homogeneity. Like all anabolic OTCs, the ovine enzyme is a trimer, constituted by identical subunits of 34 kDa. Sequence analysis of the 54 N-terminal residues of ovine OTC shows a high degree of homology with the human enzyme. The optimum pH and the Michaelis constants for the catalytic reaction were determined. The ovine enzyme is the most thermostable one among mammals OTCs, its critical temperature being 6 degrees C higher than those measured for the other enzymes. The enzyme has been crystallised and the structure determined at 3.5 A resolution. Crystals belong to the cubic P4(3)32 space group, with a = b = c = 184.7 A and a solvent content of about 80%. There is no evidence of any ligand in the active site cavity, indicating that the crystals contain an unliganded or T state of the enzyme. The unliganded OTCase enzyme adopts a trimeric structure which, in the crystal, presents a three-fold axis coincident with the crystallographic one. The conformation of each monomer in the trimer is quite similar to that of the liganded human protein, with the exception of a few loops, directly interacting with the substrate(s), which are able to induce a rearrangement of the quaternary organisation of the trimer, that accounts for the cooperative behaviour of the enzyme following the binding of the substrates.