Analysis of metallothionein by capillary electrophoresis

Metallothioneins (MTs) belong to proteins playing a key role in metal ion homeostasis, maintenance of the redox pool and free radical scavenging in both prokaryotic and eukaryotic cells. Strong interactions of the MTs with essential and non-essential metal ions as well as unique MT structure and behavior under various conditions are subjects of numerous studies. Among other analytical techniques, capillary electrophoresis (CE) has been proven to be an effective tool not only for determination of MT in biological samples, but also for the identification of its isoforms and sub-isoforms in various types of samples. Moreover, CE has a great potential to investigate MT–metal and MT–protein interactions, which has not been fully utilized yet. Thus, it is not surprising that numerous studies devoted to the optimization of CE conditions such as background electrolyte composition, electrolyte modifiers and/or capillary surface modifications have been carried out since MT's discovery in 1957. From the MTs’ detection point of view, optical detectors including absorbance, laser-induced fluorescence have been employed. Also mass spectrometric detection coupled to the various ionization techniques including inductively coupled plasma (ICP) and electrospray ionization (ESI) has been utilized for detail MT characterization and sensitive determination. In this paper, articles published from eighties to 2011 are reviewed, presenting both optimization of key parameters of CE method for MT determination as well as utilization of CE as a routine analytical technique for further investigation of complex biological and biochemical processes where MT is a key component.