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Potentiometric titration studies on globular proteins
Author(s) -
Nitta Katsutoshi,
Sugai Shintaro
Publication year - 1972
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.1972.360110909
Subject(s) - potentiometric titration , chemistry , globular protein , ionic strength , counterion , polyelectrolyte , radius , intramolecular force , poisson–boltzmann equation , analytical chemistry (journal) , computational chemistry , crystallography , chromatography , ion , aqueous solution , stereochemistry , organic chemistry , computer security , electrode , computer science , polymer
A power series method was applied to solve the Poisson‐Boltzmann equation for the spherical polyelectrolyte model and numerical calculation with an electronic computer was performed to obtain surface electric potential on rigid globular proteins. Deviation from the ideal linear relationship in Linderstrom‐Lang's plot was found to become noticeable as the surface charge density and the radius of protein increases and ionic strength decreases. The calculated surface potential was compared with potentiometric titration data of several proteins whose radii have been analyzed. Assuming the radius of the counterions to be equal to about 1.0 Å, the data for phenolic groups in ribonuclease and for carboxyl groups in conalbumin were interpreted. Reversible intramolecular transformation was found for α‐lactalbumin by comparing the present results with the potentiometric titration data for carboxyl groups. The molecular size of each protein was discussed.