Biomaterial Database

Tension in haemoglobin revealed by Fe-His(F8) bond rupture in the fully liganded T-state. 1997

M Paoli, and G Dodson, and R C Liddington, and A J Wilkinson

Department of Chemistry, University of York, York, YO1 5DD, UK.

In 1972, Perutz proposed that the low affinity of T-state haemoglobin is caused by tension in the bond between the iron and the proximal histidine, restraining the Fe from moving into the porphyrin plane on binding oxygen. This proposal has often been disputed. If such tension does exist, it will be manifest in the liganded T-state. Here we describe the structure of the fully liganded T-state cyanide complex of haemoglobin, in which the Fe-proximal histidine bond in the alpha-subunits, but not in the beta-subunits, is ruptured. This rupture uncouples the structural changes at the alpha-haem from those in the globin and the beta-haem, and demonstrates unequivocally the existence of tension and its transmission through this bond.

UI	MeSH Term	Description	Entries
D007501	Iron	A metallic element with atomic symbol Fe, atomic number 26, and atomic weight 55.85. It is an essential constituent of HEMOGLOBINS; CYTOCHROMES; and IRON-BINDING PROTEINS. It plays a role in cellular redox reactions and in the transport of OXYGEN.	Iron-56,Iron 56
D008958	Models, Molecular	Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.	Molecular Models,Model, Molecular,Molecular Model
D010108	Oxyhemoglobins	A compound formed by the combination of hemoglobin and oxygen. It is a complex in which the oxygen is bound directly to the iron without causing a change from the ferrous to the ferric state.	Oxycobalt Hemoglobin,Oxycobalthemoglobin,Oxyhemoglobin,Hemoglobin, Oxycobalt
D011166	Porphyrins	A group of compounds containing the porphin structure, four pyrrole rings connected by methine bridges in a cyclic configuration to which a variety of side chains are attached. The nature of the side chain is indicated by a prefix, as uroporphyrin, hematoporphyrin, etc. The porphyrins, in combination with iron, form the heme component in biologically significant compounds such as hemoglobin and myoglobin.	Porphyrin
D011487	Protein Conformation	The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).	Conformation, Protein,Conformations, Protein,Protein Conformations
D006418	Heme	The color-furnishing portion of hemoglobin. It is found free in tissues and as the prosthetic group in many hemeproteins.	Ferroprotoporphyrin,Protoheme,Haem,Heme b,Protoheme IX
D006441	Hemoglobin A	Normal adult human hemoglobin. The globin moiety consists of two alpha and two beta chains.
D006454	Hemoglobins	The oxygen-carrying proteins of ERYTHROCYTES. They are found in all vertebrates and some invertebrates. The number of globin subunits in the hemoglobin quaternary structure differs between species. Structures range from monomeric to a variety of multimeric arrangements.	Eryhem,Ferrous Hemoglobin,Hemoglobin,Hemoglobin, Ferrous
D006639	Histidine	An essential amino acid that is required for the production of HISTAMINE.	Histidine, L-isomer,L-Histidine,Histidine, L isomer,L-isomer Histidine
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man