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Biochemistry, Biophysics, and Structural Biology Commons

Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics

2003

Chemical activation

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Full-Text Articles in Biochemistry, Biophysics, and Structural Biology

Interaction Of Tl+ With Product Complexes Of Fructose-1,6-Bisphosphatase, Jun-Yong Choe, Scott W. Nelson, Herbert J. Fromm, Richard B. Honzatko May 2003

Interaction Of Tl+ With Product Complexes Of Fructose-1,6-Bisphosphatase, Jun-Yong Choe, Scott W. Nelson, Herbert J. Fromm, Richard B. Honzatko

Biochemistry, Biophysics and Molecular Biology Publications

The dissociation equilibrium constant for heparin binding to antithrombin III (ATIII) is a measure of the cofactor's binding to and activation of the proteinase inhibitor, and its salt dependence indicates that ionic and non-ionic interactions contribute ∼40 and ∼60% of the binding free energy, respectively. We now report that phenylalanines 121 and 122 (Phe-121 and Phe-122) together contribute 43% of the total binding free energy and 77% of the energy of non-ionic binding interactions. The large contribution of these hydrophobic residues to the binding energy is mediated not by direct interactions with heparin, but indirectly, through contacts between their ...