Figure 9. Negative ion ESI mass spectrum of mannuronate octamer after treatment with AlgE6 epimerase and G-lyase.

Peak attributions: saturated tetramer, 721.1 [M−H⁺]⁻ and 743.0 [M+Na⁺−2H⁺]⁻; saturated (unchanged) octamer, 723.0 [M+Na⁺−3H⁺/2]²⁻ and 1424.9 [M−H⁺]⁻; saturated pentamer 897.0 [M−H⁺]⁻; saturated trimer, 545.1 [M−H⁺]⁻; unsaturated tetramer, 703.0 [M−H⁺]⁻; unsaturated trimer, 527.0 [M−H⁺]⁻; unsaturated pentamer, 879.0 [M−H⁺]⁻; saturated (unchanged) heptamer, 657.5 [M+3Na⁺–5H⁺/2]²⁻ and 1248.9 [M−H⁺]⁻; saturated (unchanged) hexamer, 1073.0 [M−H⁺]⁻; and saturated (unchanged) nonamer, 819.4 [M+Na⁺+NH₄⁺−4H⁺/2]²⁻. Capillary voltage: 3.5 kV; solvent: aq. 50% methanol containing 1% ammonia.