Mass determination of human immunoglobulin IgM using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.
Monoclonal human immunoglobulin IgM has been analyzed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Using a matrix of sinapinic acid with a laser wavelength of 355 nm, positive ions with 2 to 6 charges were observed in the mass spectra. Two major molecular species were present. The molecular weights estimated from the multiply-charged signals were found to decrease systematically with decrease in the charge state of the ion. This effect was determined to stem from the non-linear influence of the initial kinetic energy of desorption on the final kinetic energy of the multiply-charged species. A method of successive approximations, with the molecular weights and desorption velocities of the analytes as variables, was used to correct for these non-linearities. Mean molecular weights for the two IgM species were found to be 939,000 +/- 2000 and 982,000 +/- 2000 Da. An initial desorption velocity of 565 +/- 10 ms/s was determined for both.
Nelson
R W
RW
Department of Chemistry and Biochemistry, Arizona State University, Tempe 85287-1604.
Dogruel
D
D
Williams
P
P
D006801:Humans; D007075:Immunoglobulin M / Q000032:analysis*; D007834:Lasers; D013058:Mass Spectrometry; D008970:Molecular Weight
D007075:Immunoglobulin M