Enzymatic degradation of hybrid ι-/ν-carrageenan by Alteromonas fortis ι-carrageenase

Hybrid iota-/nu-carrageenan was water-extracted from Eucheuma denticulatum and incubated with Alteromonas fortis 1-carrageenase. The degradation products were then separated by anion-exchange chromatography. The three most abundant fractions of hybrid iota-/nu-carrageenan oligosaccharides were purified and their structures were analyzed by NMR. The smallest hybrid was an octasaccharide with a t-t-v-t structure. The second fraction was composed of two decasaccharides with t-t-t-v-t and t-lt/vi-t-t structures. The third fraction was a mixture of dodecasaccharides which contained at least a 1-1-1-t-v-t oligosaccharide. The carbon and proton NMR spectra of the octasaccharides were completely assigned, thereby completely attributing the v-carrabiose moiety for the first time. (C) 2010 Elsevier Ltd. All rights reserved.