Fig. 6.
1H-NMR analysis of wine RG-II and the in vitro formed dimer. a Wine RG-II monomer. b De-esterified RG-II monomer. c Native RG-II dimer. d Partially de-esterified RG-II dimer. e RG-II dimer formed from the de-esterified RG-II monomer in vitro. The 1D 1H-NMR spectrum of the 1D 1H-NMR spectrum of the RG-II monomer (a) contains signals that correspond to acetyl and methyl groups. After base treatment, the signals of acetyl and methyl-esters are not observed in the spectrum of the de-esterified monomer (b), while the signals for methyl-ether remain. The removal of acetyl peaks revealed the presence of the diagnostic resonances of Kdo and Dha. The base treatment of the native dimer (c) removes methyl-esters but only partially de-acetylated the dimer (d). During in vitro dimerization of de-esterified monomer (e) several signals change. The more distinctive are the diagnostic resonances of methyl-ether (shaded orange) and 3,4 Fuc (shaded in blue), which have chemical shifts comparable to their counterparts in native and partially de-acetylated RG-II dimer