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Why Are Proteins Charged? Networks of Charge–Charge Interactions in Proteins Measured by Charge Ladders and Capillary Electrophoresis
Author(s) -
Gitlin Irina,
Carbeck Jeffrey D.,
Whitesides George M.
Publication year - 2006
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.200502530
Subject(s) - charge (physics) , electrophoresis , chemistry , static electricity , capillary electrophoresis , chemical physics , surface charge , charge density , solubility , folding (dsp implementation) , electric charge , function (biology) , biophysics , chromatography , physics , organic chemistry , biology , electrical engineering , quantum mechanics , evolutionary biology , engineering
Almost all proteins contain charged amino acids. While the function in catalysis or binding of individual charges in the active site can often be identified, it is less clear how to assign function to charges beyond this region. Are they necessary for solubility? For reasons other than solubility? Can manipulating these charges change the properties of proteins? A combination of capillary electrophoresis (CE) and protein charge ladders makes it possible to study the roles of charged residues on the surface of proteins outside the active site. This method involves chemical modification of those residues to generate a large number of derivatives of the protein that differ in charge. CE separates those derivatives into groups with the same number of modified charged groups. By studying the influence of charge on the properties of proteins using charge ladders, it is possible to estimate the net charge and hydrodynamic radius and to infer the role of charged residues in ligand binding and protein folding.