1GLI

DEOXYHEMOGLOBIN T38W (ALPHA CHAINS), V1G (ALPHA AND BETA CHAINS)

Summary for 1GLI

• Entry DOI: 10.2210/pdb1gli/pdb
• Related: 2HHB 3HHB 4HHB
• Descriptor: DEOXYHEMOGLOBIN, PROTOPORPHYRIN IX CONTAINING FE, PHOSPHATE ION, ... (5 entities in total)
• Functional Keywords: mutant, engineered mutant, site directed mutant, oxygen transport
• Biological source: Homo sapiens (human); More
• Total number of polymer chains: 4
• Total formula weight: 64940.50

Authors

Fermi, G.,Vallone, B. (deposition date: 1996-02-22, release date: 1996-08-01, Last modification date: 2024-05-22)

Primary citation

Vallone, B.,Bellelli, A.,Miele, A.E.,Brunori, M.,Fermi, G.
Probing the alpha 1 beta 2 interface of human hemoglobin by mutagenesis. Role of the FG-C contact regions.
J.Biol.Chem., 271:12472-12480, 1996

PubMed Abstract: The allosteric transition of hemoglobin involves an extensive reorganization of the alpha 1 beta 2 interface, in which two contact regions have been identified. This paper concerns at the effect of two mutations located in the "switch" (alpha C3 Thr --> Trp) and the "flexible joint" (beta C3 Trp --> Thr). We have expressed and characterized one double and two single mutants: Hb alpha T38W/beta W37T, Hb beta W37T, and Hb alpha T38W, whose structure has been determined by crystallography. We present data on: (i) the interface structure in the contact regions, (ii) oxygen and CO binding kinetics and cooperativity, (iii) dissociation rates of deoxy tetramers and association rates of deoxy dimers, and (iv) the effect of NaI on deoxy tetramer dissociation rate constant. All the mutants are tetrameric and T-state in the deoxygenated derivative. Reassociation of deoxygenated dimers is not modified by interface mutations. DeoxyHb alpha T38W/beta W37T dissociate much faster. We propose a binding site for I- at the switch region. The single mutants binds O2 cooperatively; the double one is almost non-cooperative, a feature confirmed by CO binding. The functional data, analyzed with the two-state model, indicate that these mutations reduce the value of the allosteric constant LO.

PubMed: 8647854
DOI: 10.1074/jbc.271.21.12472

Experimental method

X-RAY DIFFRACTION (2.5 Å)