Our program is directed towards enlarging the understanding of macromolecular processes involved in control and regulation. We are concerned wtih the broad theoretical formulation of allosteric models and the precise experimental description of ligand linked allosteric phenomena. The respiratory proteins exhibit these properties in diverse ways and their study should lead to an understanding of their function in terms of structure and model processes. The primary approach is to perform precise thermodynamic measurements on ligand binding reactions and to analyze the results in terms of allosteric models. We are interested in linked reaction processes which involve multiple ligand (O2, CO, H+, DPG, electron) in terms of shifts in macromolecular conformations and states of aggregation. Precise binding and energetics reaction results form the basis of detailed characterization of such cooperative processes. The methods therefore involve a combination of specially developed experimental techniques now available (thin-layer spectrophotometric binding procedures, solution titration and gas reaction microcalorimetry, and small volume pH titrations), as well as techniques in development (spectrophotometric thin layer electron binding, steady-state photochemical ligand pumping, ligand binding in crystals). Specific problems include energetic of oxygen binding to heme proteins and hemocyanins, heats of sickle cell hemoglobin aggregation, and oxygen ligation in hemoglobin crystals. The interpretation of the concerned linkage processes is facilitated by formulation of appropriate partition functions in terms of allosteric and aggregated states of the system. Detailed computer simulation and data fitting procedures are employed in the analysis of results for specific systems. Interpretation of the thermodynamic results is enhanced by use of structural information through computer graphic display. Theoretical investigation of the mathematical properties of partition functions for simplified models provides general tests for their applicability to real systems.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL022325-11
Application #
3336838
Study Section
Biophysics and Biophysical Chemistry A Study Section (BBCA)
Project Start
1978-05-01
Project End
1991-06-30
Budget Start
1988-07-01
Budget End
1989-06-30
Support Year
11
Fiscal Year
1988
Total Cost
Indirect Cost
Name
University of Colorado at Boulder
Department
Type
Schools of Arts and Sciences
DUNS #
City
Boulder
State
CO
Country
United States
Zip Code
80309
Johnson, C R; Gill, S J (1993) A thin-layer gas-solution microcalorimeter for the determination of heat binding curves. Anal Biochem 209:150-5
Johnson, C R; Gill, S J; Peters, K S (1992) Thin-layer microcalorimetric studies of oxygen and carbon monoxide binding to hemoglobin and myoglobin. Biophys Chem 45:7-15
Johnson, C R; Ownby, D W; Gill, S J et al. (1992) Oxygen binding constants and stepwise enthalpies for human and bovine hemoglobin at pH 7.6. Biochemistry 31:10074-82
Vinogradov, S N; Sharma, P K; Qabar, A N et al. (1991) A dodecamer of globin chains is the principal functional subunit of the extracellular hemoglobin of Lumbricus terrestris. J Biol Chem 266:13091-6
Doyle, M L; Simmons, J H; Gill, S J (1990) Analysis of parameter resolution from derivatives of binding isotherms. Biopolymers 29:1129-35
Arp, A J; Doyle, M L; Di Cera, E et al. (1990) Oxygenation properties of the two co-occurring hemoglobins of the tube worm Riftia pachyptila. Respir Physiol 80:323-34
Ownby, D W; Gill, S J (1990) Nonlinear optical effects in oxygen-binding reactions of hemoglobin A0. Biophys Chem 37:395-406
Gill, S J; Doyle, M L; Simmons, J H (1989) Stabilization of the T-state of hemoglobin. Biochem Biophys Res Commun 165:226-33
Robert, C H; Colosimo, A; Gill, S J (1989) Allosteric formulation of thermal transitions in macromolecules, including effects of ligand binding and oligomerization. Biopolymers 28:1705-29
Di Cera, E; Bassi, F A; Gill, S J (1989) Information theory and the analysis of ligand-binding data. Biophys Chem 34:19-28

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