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A proposed solution for the determination of the ionization constants of sets of ionizing groups in proteins
Author(s) -
Marini Mario A.,
Martin Charles J.,
Berger Robert L.,
Forlani Luciano
Publication year - 1974
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1974.360130505
Subject(s) - glycylglycine , chemistry , imidazole , ionization , acid dissociation constant , ionic bonding , potentiometric titration , pyridine , titration , zwitterion , analytical chemistry (journal) , amino acid , chromatography , stereochemistry , medicinal chemistry , ion , organic chemistry , aqueous solution , molecule , glycine , biochemistry
A mixture of acids with known p K ′ and in a known concentration was dissolved to simulate the ionic character of hemoglobin. The titration curves of the mixture were obtained in water and 3.6 M KCl at 20°C. These curves were subjected to analysis by a reiterative curve‐fitting procedure to determine if one could evaluate both the group ionization constants and the numbers of groups. This approach was successful in that the calculated parameters were within the experimental error encountered in obtaining these constants on each of the model compounds. However, analysis for the electrostatic interaction parameter w indicated that there was a possible effect on the ionization of formic acid, pyridine, imidazole, and the α‐amino group of glycylglycine in water and on imidazole and the α‐amino group of glycylglycine in 3.6 M KCl.