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Observation of cooperative ionizations in hemoglobin

Huestis, Wray H. and Raftery, Michael A. (1972) Observation of cooperative ionizations in hemoglobin. Proceedings of the National Academy of Sciences of the United States of America, 69 (7). pp. 1887-1891. ISSN 0027-8424.

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19F-Nuclear magnetic resonance studies of specifically fluorinated hemoglobin derivatives have been used to determine the apparent pKa of the histidine β146 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.

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Additional Information:© 1972 by the National Academy of Sciences. Communicated by Jerome Vinograd, May 8, 1972. We thank D.L. Huestis for assistance in calculation of titration curves for interacting ionizations. This work was supported by a National Science Foundation Predoctoral Fellowship to W.H. Huestis, by USPHS Grants GM 16424 and GM 14452, and by a National Institutes of Health Career Development Award (GM 46414) to M.A. Raftery. Contribution No. 4447 from the Church Laboratory of Chemical Biology.
Subject Keywords:19F-NMR; specifically labeled proteins; molecular regulation mechanisms; hydrophobic interactions
Issue or Number:7
Record Number:CaltechAUTHORS:HUEpnas72
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9672
Deposited By: Tony Diaz
Deposited On:27 Feb 2008
Last Modified:03 Oct 2019 00:02

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