The overall thesis of this Program is that hemoglobin (Hb) provides a well-defined, tractable """"""""molecular workbench"""""""" which can be used to develop the rules by which oligomeric protein complexes undergo allosteric regulation. A central goal is to test and further develop a predictive stereochemical model that was formulated during the last funding period. The model describes how specific residues propagate ligation-induced changes in heme structure to the subunit-subunit interfaces and thereby promote the transitions from a low affinity T structure to higher affinity T-like structures, and finally to a range of R quaternary structures.
The specific aims of this Project are to capitalize on advances in electron-nuclear double resonance (ENDOR) spectroscopy to address two basic issues. i) How are the critical interfaces coupled to ligand binding events at the hemes: What structural perturbations are induced at the liganded and liganded hemes of Hb ligation intermediates, and how do they function to modulate ligand affinity. ii) By measuring the actual distances between the heme-iron and critical heme-pocket residues, we will be able for the first time to accurately probe the tertiary-structure switch points of the Hb ligation pathway, and in so doing will suggest ways to test and refine the stereochemical allosteric model.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Program Projects (P01)
Project #
5P01GM058890-04
Application #
6564616
Study Section
Project Start
2002-01-01
Project End
2002-12-31
Budget Start
1998-10-01
Budget End
1999-09-30
Support Year
4
Fiscal Year
2002
Total Cost
$176,978
Indirect Cost
Name
University of Iowa
Department
Type
DUNS #
041294109
City
Iowa City
State
IA
Country
United States
Zip Code
52242
Kwiatkowski, Laura D; Hui, Hilda L; Karasik, Ellen et al. (2007) Mutations of the betaN102 residue of HbA not only inhibit the ligand-linked T to Re state transition, but also profoundly affect the properties of the T state itself. Biochemistry 46:2037-49
Das, Tapan K; Dewilde, Sylvia; Friedman, Joel M et al. (2006) Multiple active site conformers in the carbon monoxide complexes of trematode hemoglobins. J Biol Chem 281:11471-9
Samuni, Uri; Roche, Camille J; Dantsker, David et al. (2006) Modulation of reactivity and conformation within the T-quaternary state of human hemoglobin: the combined use of mutagenesis and sol-gel encapsulation. Biochemistry 45:2820-35
Dantsker, David; Roche, Camille; Samuni, Uri et al. (2005) The position 68(E11) side chain in myoglobin regulates ligand capture, bond formation with heme iron, and internal movement into the xenon cavities. J Biol Chem 280:38740-55
Kavanaugh, Jeffrey S; Rogers, Paul H; Arnone, Arthur et al. (2005) Intersubunit interactions associated with Tyr42 alpha stabilize the quaternary-T tetramer but are not major quaternary constraints in deoxyhemoglobin. Biochemistry 44:3806-20
Kavanaugh, Jeffrey S; Rogers, Paul H; Arnone, Arthur (2005) Crystallographic evidence for a new ensemble of ligand-induced allosteric transitions in hemoglobin: the T-to-T(high) quaternary transitions. Biochemistry 44:6101-21
Viappiani, Cristiano; Bettati, Stefano; Bruno, Stefano et al. (2004) New insights into allosteric mechanisms from trapping unstable protein conformations in silica gels. Proc Natl Acad Sci U S A 101:14414-9
Samuni, Uri; Dantsker, David; Juszczak, Laura J et al. (2004) Spectroscopic and functional characterization of T state hemoglobin conformations encapsulated in silica gels. Biochemistry 43:13674-82
Peterson, Eric S; Shinder, Roman; Khan, Imran et al. (2004) Domain-specific effector interactions within the central cavity of human adult hemoglobin in solution and in porous sol-gel matrices: evidence for long-range communication pathways. Biochemistry 43:4832-43
Hui, Hilda L; Kwiatkowski, Laura D; Karasik, Ellen et al. (2004) Ligand binding to symmetrical FeZn hybrids of variants of human HbA with modifications in the alpha1-beta2 interface. Biochemistry 43:7843-50

Showing the most recent 10 out of 37 publications