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Capillary electrophoresis investigation of a partially unfolded conformation of β 2 ‐microglobulin
Author(s) -
Lorenzi Ersilia De,
Grossi Silvia,
Massolini Gabriella,
Giorgetti Sofia,
Mangione Palma,
Andreola Alessia,
Chiti Fabrizio,
Bellotti Vittorio,
Caccialanza Gabriele
Publication year - 2002
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/1522-2683(200203)23:6<918::aid-elps918>3.0.co;2-f
Subject(s) - capillary electrophoresis , chemistry , conformational isomerism , beta 2 microglobulin , circular dichroism , fibrillogenesis , protein folding , affinity electrophoresis , amyloid (mycology) , crystallography , biophysics , chromatography , fibril , biochemistry , affinity chromatography , biology , molecule , inorganic chemistry , enzyme , organic chemistry , immunology
Dialysis‐related amyloidosis is a disease in which partial unfolding of β 2 ‐microglobulin plays a key pathogenetic role in the formation of the amyloid fibrils. We have recently demonstrated that a partially unfolded conformer of β 2 ‐microglobulin is involved in fibrillogenesis and that this species is significantly populated under physiological conditions. In this work capillary electrophoresis has been used to measure the equilibrium between the native protein and this conformer in samples known to have a higher or lower amyloidogenic potential, namely full‐length β 2 ‐microglobulin, two truncated species and a mutant, created by replacing histidine in position 31 with thyrosine. In addition, for all protein species folding stability experiments have been carried out by monitoring the secondary structure by circular dichroism at increasing concentrations of guanidinium chloride. The values of free energy of unfolding in the absence of denaturant, obtained by elaboration of these experiments, were found to be inversely correlated to the area percent of the partially unfolded conformer, as measured by capillary electrophoresis. Affinity capillary electrophoresis experiments have been also carried out under nondenaturing conditions to assess the affinity of copper and suramin to either the native form or the conformational intermediate of full‐length β 2 ‐microglobulin.