1mbc

From Proteopedia

proteopedia linkproteopedia link

spinqualitylabelsall models 1mbc, resolution 1.5Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

X-RAY STRUCTURE AND REFINEMENT OF CARBON-MONOXY (FE II)-MYOGLOBIN AT 1.5 ANGSTROMS RESOLUTION

Overview

The structure of carbon-monoxy (Fe II) myoglobin at 260 K has been solved, at a resolution of 1.5 A by X-ray diffraction and a model refined against, the X-ray data by restrained least-squares. The CO ligand is disordered, and distorted from the linear conformation seen in model compounds. At, least two conformations, with Fe--C--O angles of 140 degrees and 120, degrees, are required to model the system. The heme pocket is, significantly larger than in deoxy-myoglobin because the distal residues, have relaxed around the ligand; the largest displacement occurs for the, distal histidine side-chain, which moves more than 1.4 A on ligand, binding. The side-chain of Arg45 (CD3) is disordered and apparently exists, in two equally populated conformations. One of these does not block the, motion of the distal histidine out of the binding pocket, suggesting a, mechanism for ligand entry. The heme group is planar (root-mean-square, deviation from planarity is 0.08 A) with no doming of the pyrrole groups., The Fe--N epsilon 2 (His93) bond length is 2.2 A and the Fe--C bond length, in the CO complex is 1.9 A. The iron is the least-squares plane of the, heme, and this leads to the proximal histidine moving by 0.4 A relative to, its position in deoxy-myoglobin. This shift correlates with a global, structural change, with the proximal part of the molecule translated, towards the heme plane.

About this Structure

1MBC is a Single protein structure of sequence from Physeter catodon with SO4, HEM and CMO as ligands. Full crystallographic information is available from OCA.

Reference

X-ray structure and refinement of carbon-monoxy (Fe II)-myoglobin at 1.5 A resolution., Kuriyan J, Wilz S, Karplus M, Petsko GA, J Mol Biol. 1986 Nov 5;192(1):133-54. PMID:3820301

Page seeded by OCA on Tue Nov 20 21:17:52 2007