Electrospray ionization mass analysis of normal and genetic variants of human serum albumin
Brennan, S.O.
Clinical Chemistry 44(11): 2264-2269
1998
ISSN/ISBN: 0009-9147 PMID: 9799752 Document Number: 486511
Both normal albumin (Al A) and genetically modified forms were isolated from six heterozygous subjects. Albumins from each individual were analyzed by electrospray ionization mass spectrometry (ESI MS), and the mass was compared with that predicted from the protein sequence. In all cases, the Al A was heterogeneous, with components of mass (+- SE) 66 463 +- 4, 66 586 +- 3, and 66 718 +- 5 Da. Each genetic variant showed similar heterogeneity. The mass increase in Al Casebrook (2214 Da) was very close to that predicted (2205 Da) from protein and carbohydrate sequence analysis, whereas the increase in Al Redhill (2378 Da) was close to that expected (2392 Da) for an Arg-albumin with a disialylated N-linked biantennary oligosaccharide and an Ala fwdarw Thr mutation. The circulating proalbumins, Christchurch and Blenheim, had mass increases of 748 and 736 Da. respectively, over Al A; in excellent agreement with theoretical values of 744 and 756. Clear shifts in mass were also detected for the point substitutions 177CysfwdarwPhe (44 Da), 1AspfwdarwVal (20 Da), and Arg-albumin (160 Da).