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Nucleotide binding to creatine kinase: an isothermal titration microcalorimetry study
Author(s) -
Forstner Michael,
Berger Christine,
Wallimann Theo
Publication year - 1999
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(99)01431-3
Subject(s) - isothermal microcalorimetry , dimer , creatine kinase , titration , chemistry , nucleotide , binding site , adenosine triphosphate , active site , biochemistry , enzyme , enthalpy , thermodynamics , inorganic chemistry , physics , organic chemistry , gene
We investigated the binding of ATP in the presence and absence of Mg 2+ to dimeric muscle creatine kinase (CK) by isothermal titration microcalorimetry as a function of pH and temperature. The thermodynamic parameters for these events show that (1) binding of nucleotide to the CK active site does not involve proton exchange with the buffer and (2) the active sites are the only nucleotide binding sites on CK. Interdependence of the active sites in the dimer could not be demonstrated. As CK undergoes major structural changes upon Mg‐nucleotide binding, a thermodynamic cycle was employed to calculate the contributions of domain movements to the observed enthalpies.