Figure 11.

Proposed positions of the modifications of the novel derivatives of Ybt: 1 ([M+H]⁺: C₂₁H₂₈N₃O₅S₃⁺, calculated: m/z 498.1186, measured: m/z 498.1188, Δm 0.5 ppm), 2 ([M+H]⁺: C₂₄H₃₃N₄O₆S₄⁺, calculated: m/z 601.1277, measured: m/z 601.1282, Δm 0.8 ppm), 3 ([M+H]⁺: C₂₅H₃₅N₄O₆S₄⁺, calculated: m/z 615.1434, measured: m/z 615.1433, Δm −0.2 ppm), 4 ([M+H]⁺: C₂₄H₃₃N₄O₆S₅⁺, calculated: m/z 633.0998, measured: m/z 633.1003, Δm −0.8 ppm), 5 ([M+H]⁺: C₂₃H₃₁N₄O₆S₄⁺, calculated: m/z 587.1121, measured: m/z 587.1127, Δm 1.0 ppm), 6 ([M+H]⁺: C₂₁H₂₈N₃O₅S₄⁺, calculated: m/z 530.0906, measured: m/z 530.0911, Δm 0.9 ppm).