Figure 5. ¹H-NMR (400 MHz) spectra of the void (A) and major low-molecular-mass fraction (B) from SEC of the lyase digest of AlgE1-epimerized polyMG (F_G=0.55).

The void and the low-molecular-mass fraction are denoted I (E1) and III (E1) respectively in the SEC chromatogram in Figure 4. Δ-4G and Δ-1G signals are produced upon lyase degradation. Δ denotes a 4-deoxy-L-erythro-hex-4-enepyranosyl uronate residue. Resonance signals from G residues (G-1_red, G-5_redα and G-5_redβ) are dominating at the reducing end (B). The void fraction in (A) has F_G≥0.97. The low-molecular-mass fraction has F_G=0.5 and an alternating structure, determined as Δ-G-M-G with additional ESI-MS analysis confirming the molecular mass of DP4Δ (Table 1).