期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1972
卷号：69
期号：7
页码：1887-1891
DOI：10.1073/pnas.69.7.1887
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：19F-Nuclear magnetic resonance studies of specifically fluorinated hemoglobin derivatives have been used to determine the apparent pKa of the histidine {beta}146 imidazole in deoxyhemoglobin. The titration of this residue was found to be abnormally sharp, particularly in the presence of diphosphoglyceric acid. The explanation advanced for this unusual titration curve may have implications for the mechanism of cooperative ligand binding. The possible role of such ionizations is discussed in light of some chemical evidence that the cooperative binding process is governed to a greater extent by internal nonpolar forces than by electrostatic interactions of exposed groups.
