文摘
The storage β-polyglucan and catabolic enzyme activities of the haptophyte Pleurochrysis haptonemofera were characterized. The storage β-polyglucan was prepared by the dimethylsulfoxide-extraction method. 13C- and 1H-NMR spectroscopy revealed that the polyglucan consists of β-(1?)- and β-(1?)-linked glucose polymers, with a β-(1?)- to β-(1?)-linkage ratio of 1.5. Gel permeation chromatography showed that the molecular weight of the polyglucan is 1.1-.4?×?104?Da, with a peak at 3.4?×?104?Da. The degree of polymerization, which was estimated from the amounts of total carbohydrate and reduced ends, was 203, corresponding to 3.3?×?104?Da. A method for measurement of the β-polyglucan in a small amount of liquid culture involving a mixture of β-glucanases, Westase, was established. The β-polyglucan was localized in the soluble fraction of cells. The amount of β-polyglucan per cell increased at the stationary phase under continuous illumination and decreased in the dark, like those of storage α-polyglucans, starch of green algae and glycogen of cyanobacteria. The activities of β-1,3- and β-1,6-glucanases involved in the degradation of the storage β-polyglucan were assayed in vitro, both being optimal at pH 5.0. The β-1,3-glucanase activity, which was detected on active staining after native polyacrylamide gel electrophoresis, was partially purified by ammonium sulfate precipitation and anion exchange chromatography.