2CMM

STRUCTURAL ANALYSIS OF THE MYOGLOBIN RECONSTITUTED WITH IRON PORPHINE

Summary for 2CMM

• Entry DOI: 10.2210/pdb2cmm/pdb
• Descriptor: MYOGLOBIN, CYANIDE ION, PORPHYRIN FE(III), ... (4 entities in total)
• Functional Keywords: oxygen transport
• Biological source: Physeter catodon (sperm whale)
• Total number of polymer chains: 1
• Total formula weight: 17625.15

Authors

Sato, T.,Tanaka, N.,Moriyama, H.,Igarashi, N.,Neya, S.,Funasaki, N.,Iizuka, T.,Shiro, Y. (deposition date: 1993-12-24, release date: 1994-01-31, Last modification date: 2024-02-14)

Primary citation

Neya, S.,Funasaki, N.,Sato, T.,Igarashi, N.,Tanaka, N.
Structural analysis of the myoglobin reconstituted with iron porphine.
J.Biol.Chem., 268:8935-8942, 1993

PubMed Abstract: Sperm whale apomyoglobin was complexed with iron porphine to examine the influence of completely removed heme side chains on the entire molecular structure. Paramagnetic NMR peak from the proximal histidine of the deoxy protein ensured formation of the iron-histidine bond. Porphine pyrrole-proton NMR signals of the cyanmet and deoxy derivatives are unusually sharp single lines manifesting rapid heme rotation about the iron-histidine bond. X-ray crystallographic structure of the cyanmet derivative, determined with a final R factor of 0.21 for 11,808 independent reflections ranging from 7 to 1.8 A, was resolved at 1.8 A resolution. The result confirmed 1:1 coupling between apomyoglobin and iron porphine. The cyano ligand adopts a bent configuration with an Fe-C-N angle of 127 degrees and a Fe-CN distance of 1.89 A. The overall globin structure and side chain conformations are remarkably similar to those of native myoglobin despite intensive disruption of the original heme-globin interactions. The native apoprotein structure unexpectedly conserved even after iron porphine insertion demonstrates that the complex polypeptide fold of holomyoglobin is more inherent in the amino acid sequence than is generally believed.

PubMed: 8473336

Experimental method

X-RAY DIFFRACTION (1.8 Å)