Abstract
A new approach for the speciation of metallothioneins (MT) in human brain cytosols is described. The analysis is performed by application of a newly developed coupling of capillary electrophoresis (CE) with inductively coupled plasma–sector field mass spectrometry (ICP–SFMS). Isoforms of metallothioneins are separated from 30–100 µL sample volumes by CE and the elements Cu, Zn, Cd, and S are detected by use of ICP–SFMS.
The extraction of cytosols is the first step in the analytical procedure. Tissue samples from human brain are homogenized in a buffer solution and submitted to ultra-centrifugation. The supernatant is defatted and the cytosol pre-treatment is optimized for CE separation by matrix reduction. The buffer concentration and pH used for capillary electrophoretic separation of metallothionein from rabbit liver were optimized. CE with ICP–MS detection is compared to UV detection. In the electropherograms obtained from the cytosols three peaks can be assigned to MT-1, MT-2, and MT-3. As an additional method, size-exclusion chromatography (SEC) is applied. Fractions from an SEC separation of the cytosol are collected, concentrated, and then injected into the CE.
The detection of sulfur by ICP–SFMS (medium resolution mode) and quantification by isotope dilution have also been investigated as a new method for the quantification of MT isoforms.
The analytical procedure developed has been used for the first time in comparative studies of the distributions of MT-1, MT-2, and MT-3 in brain samples taken from patients with Alzheimer’s disease and from a control group.
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Prange, A., Schaumlöffel, D., Brätter, P. et al. Species analysis of metallothionein isoforms in human brain cytosols by use of capillary electrophoresis hyphenated to inductively coupled plasma–sector field mass spectrometry. Fresenius J Anal Chem 371, 764–774 (2001). https://doi.org/10.1007/s002160101019
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DOI: https://doi.org/10.1007/s002160101019