The combination of capillary electrophoresis (CE) with electrospray ionization (ESI) mass spectrometry has proven to be broadly applicable to a wide range of biologically important compounds. When combined with Fourier transform ion cyclotron resonance (FIICR) mass spectrometry, the combined method, in addition to highresolution separations, affords high-resolution precision mass measurements for analytes separated from complex mixtures. Direct chemical analysis of single cells has received considerable attention in recent years; the single cell approach provides a major step toward answering important questions in the field of cellular biochemistry. In this work we present preliminary results which demonstrate the feasibility of using the CE-ESI-F1ICR combination as a high-performance detection scheme for the analysis of cellular proteins acquired directly from small populations (i.e., 5-10) of intact living cells. The human erythrocyte was chosen as a model system owing to its availability, relatively homogeneous composition, and thorough documentation of contents by previous researchers. In this work we demonstrate the on-line acquisition of high-resolution mass spectra (average resolution ≥ 45 000 fwhm) of both the α and the β chains of hemoglobin acquired from the injection of 10 human erythrocytes (corresponding to 4.5 finol of hemoglobin). Given the extremely small volume of the human erythrocyte (typically 87 fL/cell), the techniques implemented here should also be adaptable to the study of larger mammalian cell systems.
All Science Journal Classification (ASJC) codes
- Analytical Chemistry