Abstract
Recently, we showed that the signal intensity of intact protein by matrix-assisted laser desorption/ionisation (MALDI) mass spectrometry measurement can be enhanced at least an order of magnitude by the addition of Tween80 to the analyte solution. We did not ascertain whether this effect was limited to Tween80 or if it was more universal of biological detergents. This paper discusses our investigations into this question. A variety of chemically diverse detergents were added to analyte solutions containing bovine serum albumin (BSA) to determine whether there was significant signal enhancement. The addition of Tween20, Tween80, Triton X-100 and Triton X-114 improved the attainable sensitivity of intact protein MALDI mass spectrometry compared to spectra acquired without detergent. In some cases there was considerable improvement in signal—for example, with Triton X-100 two charge states (the +1 and +2) of BSA (3.9 fmol) could easily be observed. Another advantage of this process is that the detergent can be added directly to the matrix solution reducing sample handling and preparation time. We propose this phenomenon results from the ability of these detergents to increase the solubility of the protein via hydrophobic and hydrophilic interactions between the detergent and protein. The increased solubility allows for more uniform deposition of the analyte/matrix mixtures producing an evenly distributed layer of analyte especially useful for data acquisition using an automated laser firing sequence.
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