Showing papers on "Cooperative binding published in 1967"

Relation of protein subunit interactions to the molecular species observed during cooperative binding of ligands.

Abstract: To understand cooperative effects in proteins and regulatory enzymes it is necessary to correlate the changes in apparent affinity of the ligand with the changes in the protein structure. A model based on sequential changes in the conformations of subunits of the protein can explain ligand binding and enzyme activity in hemoglobin and regulatory proteins.1-3 In Figure 1, a schematic illustration of the molecular species potentially present in a tetrameric protein in which the ligand can bind to only one of two subunit conformations is shown. Not all of these molecular species are necessarily present in appreciable concentrations, and models with fewer species can, for example, rationalize the 02 binding curve of hemoglobin. ' 4 The actual molecular species present under different experimental conditions can clarify the nature of the subunit interactions and give clues as to the evolutionary significance of cooperative properties. Some analyses of these relationships are discussed in this paper. In Figure 2, the conformational changes of an isolated subunit or a monomeric