Glu-fibrinopeptide

Using Table 5.6 (see p. 156), propose a sequence for glu-fibrinopeptide B based on the product-ion MS-MS spectrum shown in Figure 4.20. 

Appropriate standard peptides for calibration with monoisotopic molecular masses covering, for example, the mass range 500-3000 Da (27). Glu-fibrinopeptide-B is also used as external calibrant for MS" experiments (28). 

Figure 5.12 Mass spectrum averaged on a 2min acquisition of the signal analysis of a 10 2gM Glu Fibrinopeptide B sample under 1.2 kV ionization voltage using the micro-nib source with an 8 pm slot dimension. The inset shows the corresponding TIC signal recorded for 2 min (RSD of 7.2%). (Adapted with permission from Ref. 13).

We finally validated the functioning of nib emitter tips with reduced section area (h x w = 25 pm x 6 pm) (see Figure 5.14A) using a Glu-Fibrinopeptide B sample at 1 pM. The required ionization voltage here was lower than 1 kV, as illustrated by the mass spectrum presented in Figure 5.14B and resulting from 1 min acquisition of the signal for the analysis of a 1 pM Glu-Fibrinopeptide B... 

Mass spectrometry tests were conducted as described before, with an ion trap mass spectrometer using the second setup whereby HV is directly applied onto the supporting silicon wafer. The same standard peptide as before was used, Glu-Fibrinopeptide B, at a concentration of 1 pM. For the first series of tests, we decided to investigate the range of FIV which would give an electrospray working with solutions of 50 50 MeOH-H20 acidified with 0.1% HCOOH. 

Figure 5.20 Mass spectra obtained using polySi-based nano-nibs and averaged over a period of lmin. (A) Reserpine sample at 200 pM in 50 50 H20- MeOH, 0.1% HCOOH, HV of 1.5 kV (B) Glu-Fibrinopeptide B sample at 10 pM in 50 50 H20 MeOH, 0.1% HCOOH, HV of 1.5 kV.

FIGURE 10.12 MALDI-TOF mass spectrum of the 14-residue [Glu ]fibrinopeptide following eight cycles of manual ladder-generating Edman chemistry. Reprinted with permission from reference 20. 

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