Structural analysis of protein variants by mass spectrometry: characterization of haemoglobin providence using a grand-scale mass spectrometer.

A grand-scale mass spectrometer with high mass resolution and high transmission was employed for the analysis of haemoglobin variant. Two variants were isolated from a haemolysate by chromatography. Secondary ion mass spectrometry of complex peptide mixtures derived from these variants precisely determined the molecular weight of abnormal peptides. The molecular weight, 2857.4 and 2858.4, indicated the amino acid substitutions of asparagine and aspartic acid, respectively, for lysine at position 82 of beta globin chain. The mutations had been reported in haemoglobin Providence.