Analysis of metallothioneins by means of capillary electrophoresis coupledto electrospray mass spectrometry with sheathless interfacing

Capillary electrophoresis (CE) coupled to electrospray mass spectrometry vi a sheathless interfacing has been applied to the analysis of mammalian meta llothionein (MT) extracts. In a rabbit-liver extract, four (MT-2C, MT-2A, M T-2D and MT-2E) out of six known MT sub-Isoforms were unambiguously identif ied under three CE-resolved peaks. A fourth peak was found to contain MT-1A and/or MT-2B, whose molecular masses differ by only 1 Da. Traces of non-N- acetylated MT-2D and MT-2E were observed in a fifth, minor peak In a rat-li ver extract, both MT-1 and MT-2 were resolved and identified. Non-N-acetyla ted MT-2 was also identified in a resolved, minor peak. Minimum detectable amounts of MTs have been estimated to be approximately 0.6 fmol per sub-iso form. Copyright (C) 1999 John Wiley & Sons, Ltd.