Detection of intact hemoglobin from aqueous solution with laser desorption mass spectrometry

Laser induced liquid beam ionization/desorption mass spectrometry (LILBID-MS) is a new desorption method recently developed in our laboratory. This method allows ions to be desorbed directly from the liquid phase into the high-vacuum region of a mass spectrometer. This method has now been applied to the detection of noncovalent protein-protein complexes. The example given in this paper is the quartenary complex of human hemoglobin. For the first time, the intact hemoglobin could be detected by laser desorption mass spectrometry. Furthermore, evidence for the specificity of the complex is given.