Field desorption mass spectra of tryptic peptides of human hemoglobin chains

Field desorption mass spectra of tryptic peptides of normal human hemoglobin α-, β-, γ-, δ-chains and abnormal β-chain of hemoglobin S were studied. Almost all mass peaks of the protonated molecular ions of tryptic peptides and many doubly charged ions were observed. The molecular weights of all tryptic peptides were estimated from the mass spectra, the heaviest mass being m/z 2955, and coincided with the values obtained from the known amino acid sequences. The different chains of hemoglobin can be distinguished by their field desorption mass spectra. The mass spectrum of abnormal β-chain of hemoglobin S (sickle-cell-anemia) showed a shift of the characteristic line due to the mutation of amino acid.