Michele Müller, A. Haeberli
Feb 28, 1994
Citations
0
Influential Citations
7
Citations
Journal
FEBS Letters
Abstract
Pure ethylenediaminetetraacetic acid tetrasodium salt (EDTA · Na4) in water showed a pH‐dependent change of optical density detected in the ultraviolet region. The most important change was found between pH 4 and 8, corresponding to the deprotonation of the third ionizable group having a pK of 6.2. The absorbance change was reversible and depended on the addition/removal of only 1 proton equivalent. The presence of supramolecular aggregates was suggested by size‐exclusion chromatography, dialysis and cryo‐electronmicroscopy. The molecular weight of EDTA supramolecular aggregates was 10–15,000 and 8–14,000, as determined by gel chromatography and dialysis, respectively. Cryo‐electronmicroscopy revealed structures of 2–4 nm in diameter.