Comprehensive metalloprotein analysis from a single separation record
| Authors | |
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| Year of publication | 2013 |
| Type | Conference abstract |
| MU Faculty or unit | |
| Citation | |
| Description | Metals play a crucial role in physiology and pathology of biological systems. It has been estimated that the metalloproteins encompass about one third of all proteins; they are involved in the regulation of protein expression, metal transportation, homeostasis or detoxification process. A novel method for comprehensive multidimensional analysis of metalloproteins is presented here. This approach is based on an off-line coupling of a single micro-column separation run to both substrate-assisted laser desorption (SALD) inductively coupled plasma (ICP) mass spectrometry (MS) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI) MS. The effluent fractions are collected on a custom-designed Au-coated polyethylene terephthalate glycol (PETG) sample target that is compatible to both MS methods. The whole concept is demonstrated on successive analysis of rabbit-liver metallothionein (MT) isoform mixture: A single separation record analyzed consecutively by MALDI MS and SALD ICP MS provides information about both molecular mass of present proteins and metal distribution and quantity, respectively. To take full advantage of the off-line coupling potential, two different MALDI matrices in solutions of acidic and neutral pH were applied at the adjacent spots corresponding to MT peak. Thus additional information can be obtained: While under acidic condition the information about protein apoforms is revealed, the metal-protein complexes can be detected at neutral pH. The conditions of separation system as well as the performance of the designed sample target in comparison with commonly used MALDI targets or uncoated PETG sheets are investigated in detail. We believe the presented method can be a viable alternative to on-line coupling employing electrospray ionization and nebulizer ICP MS. |
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