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Anion binding to a protein–protein complex lacks dependence on net charge
Author(s) -
Waldron Travis T.,
Modestou Modestos A.,
Murphy Kenneth P.
Publication year - 2003
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.0230703
Subject(s) - isothermal titration calorimetry , chemistry , energetics , ion , crystallography , calorimetry , hydrogen bond , titration , binding site , plasma protein binding , inorganic chemistry , biochemistry , molecule , thermodynamics , organic chemistry , physics
The binding of anions to proteins occurs in numerous physiological and metabolic processes. In an effort to understand the factors important in these interactions, we have studied the weak binding of phosphate and sulfate to a protein–protein complex using isothermal titration calorimetry. To our knowledge, this is the first system in which the thermodynamics of anion binding have been determined calorimetrically. By studying both phosphate and sulfate binding and using a range of pH values, the charge on the anion was varied from ∼ −1 to −2. Surprisingly, no dependence of the binding energetics on the charge of the anion was observed. This result indicates that charge–charge interactions are not the dominant factor in binding and suggests the importance of hydrogen bonding in specifically recognizing and coordinating anions.