Structural analysis of laminarans by MALDI and FAB mass spectrometry

MALDI and FAB mass spectrometry were applied to eight samples of laminarans from different algal species. The existence of both M-chains (mannitol-containing) and G-chains (mannitol-free) was confirmed for six of them, as well as the absence of M-chains for laminarans from two Cystoseira sp. It was found that Cystoseira barbata and C. crinita glucans contain a small percentage of N-acetylhexosamine-terminated chains. This is the first observation of nitrogen-containing sugars in laminarans. The presence of cyclic structures in some laminaran samples is suggested by the MALDI and FAB data. This study demonstrates the power of modern mass spectrometry for defining d.p. profiles in complex mixtures of polysaccharides and for rapidly and sensitively revealing the presence of novel components.