The commercial agar from New Zealand Pterocladia species

Abstract

The compositions of a laboratory extracted agar and commercial agar prepared from a mixture of New Zealand Pterocladia species (P. lucida and P. pinnata) are reported. The structure of the commercial agar has been studied by using methylation analysis, and the results, when considered along with the 13C n.m.r. spectrum, show that the polysaccharide has a structure which is close to that of agarose. Less than 1% of the agar is made up of 1,3-linked 6-O-methyl-D-galactopyranosyl residues. After complete acid hydrolysis, only 2% of the total galactose obtained was the L-enan-tiomer. Reaction of the Pterocladia agarose in the presence of the enzyme D-galactose oxidase showed that the 1,3-linked D-galactosyl residues are oxidized even if they occur in an ordered situation within the molecule.