Publication details

Off-line MALDI and ICP MS detection of a single record of metallothionein separation

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Year of publication 2013
Type Conference abstract
MU Faculty or unit

Central European Institute of Technology

Description It is estimated that one third of all proteins require metals to carry out their functions. Therefore, the analyses of native metal-protein and metal-metabolite complexes by hyphenated techniques that combine separation with a specific detection is of growing importance. A new concept of an off-line multidetection platform for metalloprotein/metallopeptide analysis of fractions collected from a single run of capillary electrophoresis (CE) or liquid chromatography (LC) is presented. The separation record, i.e. fractions collected on a target, are analyzed sequentially with MALDI MS and SALD ICP MS. Thus, a single separation can yield both proteomic and metallomic information. Moreover, the off-line nature of the analysis provides further possibilities, such as laser-induced fluorescence detection or on target digestion. Here, the approach is demonstrated on the successful reverse phase HPLC-ESI/MALDI/SALD ICP MS analysis of purified rabbit liver metallothionein (MT) isoforms: The MT1a, MT2d and MT2e were eluted out of a C18 column with ammonium acetate buffer (pH 7.5)/ammonium acetate buffer (pH 7.5) in 60% methanol at 27.8, 29.0 and 33.4 min, respectively. Using a flow splitter, the MT isoforms were detected by on-line ESI–TOF MS and the fractions of the separation were simultaneously collected on a suitable target for successive off-line detection by MALDI and SALD ICP MS. CE was successfully coupled to both MALDI and SALD ICP MS. It can offer enhancement of separation efficiency, modified separation selectivity and high sensitivity. On the other hand, low amount of injected samples poses a challenge for both MALDI and SALD ICP MS detection modes. Initial results of CE as a prospective method for separation of MT isoforms will be presented. The influence of liquid junction interface, fraction collector and MALDI-TOF MS settings and other analysis parameters is discussed in detail.
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