STRUCTURAL-ANALYSIS OF CARRAGEENANS FROM THE TETRASPORIC STAGES OF THE RED ALGAE, GIGARTINA-LANCEATA AND GIGARTINA-CHAPMANII (GIGARTINACEAE, RHODOPHYTA)

The use of modern analytical techniques has facilitated the identifica tion of the polysaccharides from tetrasporophytic Gigartina lanceata a nd Gigartina chapmanii. The G. lanceata polysaccharide corresponds, ve ry closely, to the idealised structure of lambda-carrageenan ([G2S-D2S ,6S](n)). That from G. chapmanii contains predominantly xi-carrageenan ([G2S-D2S](n)), but with about one in seven of the 3-linked units als o has a pyruvate acetal group at the 4- and 6-positions, one in four o f the 4-linked units is also sulfated at the 6-position, and a small b ut significant number of 4-1inked 3,6-anhydrogalactosyl 2-sulfate unit s are present. (C) 1998 Elsevier Science Ltd. All rights reserved.