Acid dissociation constants of substituted methanediphosphonic acids. Correlation with phosphorus-31 magnetic resonance chemical shift and with Taft σ*

1967 ◽  
Vol 71 (13) ◽  
pp. 4194-4202 ◽  
Author(s):  
Robert J. Grabenstetter ◽  
Oscar T. Quimby ◽  
Thomas J. Flautt
Keyword(s):  
Magnetic Resonance ◽  
Chemical Shift ◽  
Dissociation Constants ◽  
Acid Dissociation ◽  
Acid Dissociation Constants

Theoretical calculations of acid-dissociation constants of proteins

1998 ◽  
Vol 76 (2-3) ◽  
pp. 198-209 ◽  
Author(s):  
André H Juffer
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Dissociation Constants ◽  
Theoretical Calculations ◽  
Acid Dissociation ◽  
Continuum Electrostatics ◽  
Acid Dissociation Constants ◽  
Computational Procedures ◽  
Nuclear Magnetic

The purpose of this review is to introduce several computational procedures for the determination of acid-dissociation constants (pKa) of titratable groups in proteins. Several concepts, such as continuum electrostatics and the exact meaning of intrinsic and apparent pKas, will be explained in some detail. Each of the methods will be judged on its merits, and some comparisons between the methods will be presented. While the emphasis of this review will be on theoretical formulations, the experimental determination by means of nuclear magnetic resonance will be briefly explained. The determination of individual pKa values by nuclear magnetic resonance in combination with computationally determined pKas can provide unique information about the pH-dependent properties of proteins and their complexes with peptides, DNA, and ligands.Key words: acid-dissociation constants, NMR, continuum electrostatics, dielectric constant of proteins, Monte Carlo, molecular dynamics.

Nuclear magnetic resonance studies of the acid–base chemistry of amino acids and peptides. III. Determination of the microscopic and macroscopic acid dissociation constants of α,ω-diaminocarboxylic acids

1976 ◽  
Vol 54 (21) ◽  
pp. 3392-3400 ◽  
Author(s):  
Thomas L. Sayer ◽  
Dallas L. Rabenstein
Keyword(s):  
Chemical Shift ◽  
Dissociation Constants ◽  
Nonlinear Least Squares ◽  
Acid Dissociation ◽  
Acid Base ◽  
Acid Dissociation Constants ◽  
Ammonium Group ◽  
Titration Curves ◽  
Chemical Shift Titration ◽  
The Difference

The acid–base chemistry of 2,3-diaminopropionic acid (dap), 2,4-diaminobutyric acid (dab), ornithine (orn), and lysine (lys) has been studied by 13C and proton nmr spectroscopy. Macroscopic acid dissociation constants for titration of the two ammonium groups of each molecule have been calculated from the 13C chemical shift titration curves for the alkyl carbon atoms by nonlinear least squares curve fitting methods. Microscopic acid dissociation constants for the simultaneous titration of the two ammonium groups of protonated orn and lys have been obtained from their proton chemical shift titration curves and from the 13C titration curves for orn and dap. The results indicate that the α-ammonium group of each of these α,ω-diaminocarboxylic acids is more acidic than its ω-ammonium group, but that the difference decreases as the number of carbons separating the ammonium groups decreases so that the acidities of the two ammonium groups of dap are almost identical. Results of pmr studies of the acid–base chemistry of glycyl-L-lysine and L-lysylglycine also are reported.

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