1bcf
From Proteopedia
THE STRUCTURE OF A UNIQUE, TWO-FOLD SYMMETRIC, HAEM-BINDING SITE
Overview
Bacterioferritin of Escherichia coli, also known as cytochrome b1, is a hollow, nearly spherical shell made up of 24 identical protein subunits and 12 haems. We have solved this structure in a tetragonal crystal form at 2.9 A resolution. We find that each haem is bound in a pocket formed by the interface between a pair of symmetry-related subunits. The quasi-twofold axis of the haem is closely aligned with the local twofold axis relating these subunits. The axial ligands of the haem are sulphurs of two equivalent methionyl residues (Met 52) from the symmetry-related subunits. A cluster of four water molecules is trapped in the gap between the upper edge of the haem and two extended protein loops which close off the haem from the outer aqueous environment. This is the first structure of a bis-methionine ligated haem-binding site and the first case of a twofold symmetric haem-binding site.
About this Structure
1BCF is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
Reference
Structure of a unique twofold symmetric haem-binding site., Frolow F, Kalb AJ, Yariv J, Nat Struct Biol. 1994 Jul;1(7):453-60. PMID:7664064 Page seeded by OCA on Fri May 2 11:20:14 2008
