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. Author manuscript; available in PMC: 2014 Jan 22.
Published in final edited form as: Biochemistry. 2013 Jan 11;52(3):520–536. doi: 10.1021/bi301074r

Figure 5. Analysis of the phosphorylated and unphosphorylated SLBP RNA Binding and Processing domains (RPD) by mass spectrometry.

Figure 5

(A) The MALDI-TOF mass spectrum of the bacterially expressed unphosphorylated hSLBP RPD is shown. The ratio of the masses obtained for the monomer: dimer: trimer: tretramer: hexamer obtained from the peak intensities was 32:7: 35.3: 9.9: 12.4: 9.7.

(B) The electrospray mass spectrum (ES-MS) of the phosphorylated hSLBP RBD obtained on a Qtof-Micro mass analyzer is shown. The mass obtained was 11,783.00 Da, corresponding to a single phosphate at Thr230, cleavage of the N-terminal Met, and acetylation of the N-terminal serine. On the basis of peak heights, the monomer: dimer: trimer: tetramer ratio was 86.6: 5.6: 3.9: 3.8.