A novel highly acidic polysaccharide with inhibitory activity on calcification from the calcified scale "coccolith" of a coccolithophorid alga, Pleurochrysis haptonemofera.

Coccolith, a calcified scale with species-specific fine structure produced by marine unicellular coccolithophorid algae, consists of calcium carbonate (CaCO(3)) crystals and a small amount of organic matrices. A novel polysaccharide named coccolith matrix acidic polysaccharide (CMAP) was isolated from the coccolith of a coccolithophorid alga, Pleurochrysis haptonemofera. The structure of CMAP was determined by chemical analysis and NMR spectroscopy including COSY, TOCSY, HMQC, and HMBC to be a polysaccharide composed of the following unit: -->4) l-iduronic acid (alpha1-->2) meso-tartaric acid (3-->1) glyoxylic acid (1-->. It has four carboxyl groups per a disaccharide unit as observed in another polysaccharide PS-2 characterized previously in Pleurochrysis carterae. CMAP showed a strong inhibitory activity on CaCO(3) precipitation. These results suggest that CMAP serves as a regulator in the calcification of the coccolith.