Figure 3.

Proposed structures of reaction products of GBG after incubation with laccase and LMS. The dotted lines represent the proposed fragmentation pattern, resulting in the MS² fragments reported in Table 1. The fragmentation pattern of GBG and GBG-ABTS CPI_ox originate from the parent ions [M+Na]⁺ and [M–3H]^2–, respectively. All other patterns originate from the parent ion [M–H]⁻. In the coupling products and oligomers, the positions of coupling could not be identified based on MS² spectra and are therefore based on the literature.^31,34,35 The position of the second interunit bond in the GBG trimer is not specified, as there is no experimental evidence for either C–C or C–O linkage. Fragmentations with an * (in GBG-ABTS CPIox and ABTS CLP) are suggested to be radical fragmentations.