Characterization of pH titration shifts for all the nonlabile proton resonances in a protein by two-dimensional NMR: The case of mouse epidermal growth factor
- Tokyo Metropolitan Inst. of Medical Science (Japan)
The pH titration shifts for all the nonlabile proton resonances in a 53-residue protein (mouse epidermal growth factor) were measured in the p{sup 2}H range 1.5-9 with two-dimensional (2D) {sup 1}H NMR. The 2D NMR pH titration experiment made it possible to determine the pK values for all the ionizable group which were titrated in the pH range 1.5-9 in the protein. The pK values of the nine ionizable groups ({alpha}-amino group, four Asp, two Glu, one His, and {alpha}-carboxyl group) were found to be near their normal values. The 2D titration experiment also provided a detailed description of the pH-dependent behavior of the proton chemical shifts and enabled us to characterize the pH-dependent changes of protein conformation. Analysis of the pH-dependent shifts of ca. 200 proton resonances offered evidence of conformational changes in slightly basic pH solution: The deprotonation of the N-terminal {alpha}-amino group induced a widespread conformational change over the {beta}-sheet structure in the protein, while the effects of deprotonation of the His22 imidazole group were relatively localized. The authors found that the 2D NMR pH titration experiment is a powerful tool for investigating the structural and dynamic properties of proteins.
- OSTI ID:
- 5014451
- Journal Information:
- Biochemistry; (United States), Vol. 30:20; ISSN 0006-2960
- Country of Publication:
- United States
- Language:
- English
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550601* - Medicine- Unsealed Radionuclides in Diagnostics