Tripeptides, mass spectra

Figure 2. Threshold energy fluence for the appearance of the tripeptide mass spectrum with distinct chromophore R+ photoion as a function of the UV laser pulse duration (from Ref. 8).

Figure 6.2 ESI mass spectrum of an equimolar mixture of six tripeptides (Gly-Gly-X, where X is Gly (G), Ala (A), Val (V), Leu (L), Phe (F), or Tyr (Y)). The response increases as the non-polar character of the side-chain of the C-terminal amino acid increases. Reprinted from [49] with permission. 2000, American Chemical Society.

Figure 77. OH /NICI mass spectrum of tripeptide mixture [222].

Figure 2.7. A mass spectrum comparing the responses of the six tripeptides whose structures differ only by what R-group is attached to the C-terminal residue. Although the peptides are prepared at equimolar concentration, their responses differ signi ficantly. The additional small peaks in the mass spectrum represent peptide methanol clusters, whose response is insignificant with respect to that of the bare peptides. (Reprinted from Ref. 50, with permission.)...

Our experiments with tryptophan (Trp) and a tryptophan-containing tripeptide revealed some specific features that are especially evident from comparison between the mass spectra resulting from irradiation with femtosecond and nanosecond laser pulses in the UV (308 nm) and visible (620 nm) regions of the spectrum. The degree of fragmentation depends on both... 

Fig. 14 Top panel. Time-of-flight mass spectra illustrating formation of H2 adducts to ESI generated ions in a 10 K ion trap (a) the dipeptide (GlyGlyH ) and (b) the tripeptide indicated in the inset. Bottom panel. Vibrational predissociation spectrum of H2-tagged GlyGlyH (solid black line). The gray overlay in trace (c) is the previously reported IRMPD spectrum [146] of the bare ion at 300 K. Stars in top panel indicate presence of naturally occurring C isotopologues...

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