title: A quantitative analysis of the effects of 2,3-diphosphoglycerate, adenosine triphosphate and inositol hexaphosphate on the oxygen dissociation curve of human haemoglobin.
abstract: 1. Oxygen dissociation curves have been measured for human haemoglobin solutions with different concentrations of the allosteric effectors 2,3-diphosphoglycerate, adenosine triphosphate and inositol hexaphosphate. 2. Each effector produces a concentration dependent right shift of the oxygen dissociation curve, but a point is reached where the shift is maximal and increasing the effector concentration has no further effect. 3. Mathematical models based on the Monod, Wyman & Changeux (1965) treatment of allosteric proteins have been fitted to the data. For each compound the simple two-state model and its extension to take account of subunit inequivalence were shown to be inadequate, and a better fit was obtained by allowing the effector to lower the oxygen affinity of the deoxy conformational state as well as binding preferentially to this conformation.
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000494:Allosteric Regulation; D001665:Binding Sites / Q000187:drug effects; D004163:Diphosphoglyceric Acids / Q000494:pharmacology*; D006454:Hemoglobins / Q000378:metabolism*; D006801:Humans; D010100:Oxygen / Q000097:blood*; D010833:Phytic Acid / Q000494:pharmacology*
chemical_list: D004163:Diphosphoglyceric Acids; D006454:Hemoglobins; D010833:Phytic Acid; D000255:Adenosine Triphosphate; D010100:Oxygen