Figure 4.

The product ion mass spectra of CP962 [Thr+Arg+Ahp+Phe+MePhe+Val]Asp+BA with precursor ion [M + H]+ at m/z 963. The spectra were recorded with application of a hybride quadrupole/time-of-flight mass spectrometer (QTOF) (A) and a hybride triple quadrupole/linear ion trap mass spectrometer (QTRAP) (B). The mass signals were assigned to the following fragments: 945 [M + H − H₂O]⁺, 917 [M + H − H₂O − CO]⁺, 846 [M + H − Val − H₂O]⁺, 828 [M + H − Val − 2H₂O]⁺, 778 [M + 2H − (BA + Asp)]⁺, 760 [M + 2H − (BA + Asp) − H₂O]⁺, 742 [M + 2H − (BA + Asp) − 2H₂O]⁺, 685 [M + H − (Val + MePhe) − H₂O]⁺, 425 [BA + Asp + Thr + Arg + H − H₂O]⁺, 404 [Ahp + Phe + MePhe + H − H₂O]⁺, 297 [Asp + Thr + Val + H − H₂O]⁺, 243 [Ahp + Phe + H − H₂O]⁺, 215 [Ahp + Phe + H − H₂O − CO]⁺, 134 MePhe immonium ion, 120 Phe immonium ion, 70-Arg.