Location of the Sulfate Groups in κ-Carrageenan from Gigartina Tenella

Abstract

Abstract Location of the sulfate groups in κ carrageenan from G. tenella has been re-investigated by adapting the method, which was devised by Bouveng for locating the acetyl groups in hemicellulose. In this method, the sulfate groups were replaced by methyl groups through a series of reactions consisting of blocking the free hydroxyl groups with phenylcarbamoyl groups, removing the sulfate groups and methylating the newly formed hydroxyl groups. The blocking substituents were then removed, and the positions of the methoxyl groups were investigated by the standard method. The results have shown, in accordance with the conclusion based on the methylation data, that one forth of the 1,4-linked 3,6-anhydro-d-galactose residues are 2-sulfated and that the 1,3-linked d-galactose residues are 4-sulfated. No evidence was obtained to indicate the presence of d-galactose 2,6-disulfate, which had been presumed by other workers. The problem concerning the acyl migration of the blocking groups during the process has also been discussed.