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Updated: Jun 28, 2026
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Determination of the Gas-phase Acidities of Oligopeptides
Published on: June 24, 2013
Microscopic acid-base equilibria of arginine
1Department of Inorganic and Analytical Chemistry, L. Eötvös University, H-1518 Budapest 112, Pf. 32, Hungary.
Talanta
|December 1, 1991
Summary
This study quantifies protonation constants for arginine and citrulline, revealing exceptionally high basicity for arginine's guanidino group. These findings aid in understanding molecular interactions and complex formation.
Area of Science:
- Biochemistry
- Chemical Thermodynamics
- Analytical Chemistry
Background:
- Arginine and citrulline are crucial biomolecules with complex protonation behaviors.
- Accurate protonation constants are essential for understanding their roles in biological systems.
- Previous data on arginine's guanidino group basicity were limited.
Purpose of the Study:
- To determine macro- and microconstants for arginine and citrulline protonation.
- To establish reliable microscopic basicity values for the arginine guanidino group.
- To investigate protonation-dependent interactions and their implications.
Main Methods:
- Potentiometric titration combined with deductive analysis.
- Determination of macro- and microconstants.
- Calculation of interactivity parameters.
Main Results:
- Quantified three and two macroconstants for arginine and citrulline, respectively.
- Determined twelve and four microconstants for arginine and citrulline.
- Reported unprecedentedly high guanidino group basicity for arginine (14.7-15.0 log k).
- Calculated guanidino-amino (0.2 log k) and guanidino-carboxylate (0.1 log k) interactivity parameters.
Conclusions:
- Established a comprehensive understanding of arginine and citrulline protonation.
- Microspeciation diagrams provide insights into pH-dependent behavior.
- The findings are critical for predicting metal complex formation and bioligand associations.
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