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The characteristics of protein-bound polysaccharides (PBP) which were isolated and purified from the sawdust mycelia of Agrocybe cylindracea were investigated. The yield of crude protein-bound polysaccharides (Fr.CB) extracted with boiling water and precipitated with 95% ethanol, was 0.74% based on the original sawdust mycelia. The Fr.CB was purified by the membrane filtration, ion exchange chromatography and gel filtration. The Fr.B fraction of which the molecular weight is over 300 KDa, was isolated from the Fr.CB using membrane filtration, and the yield was 38.6% based on the Fr.CB. This result indicates that high molecular protein-bound polysaccharides are the dominent components of the Fr.CB. Two fractions (Fr.B-1, Fr.B-2) were also isolated from the Fr.B using ion exchange chromatography, and the yields were 17.3% (Fr.B-1) and 10.3% (Fr.B-2), respectively. The Fr.B-1 was concentrated and gel-filtrated, and the single peak, thought to be nearly pure protein-bound polysaccharides, was obtained. The yield of final fraction (Fr.B-1-β) was 42.5% based on the Fr.B-1. The molecular weight of Fr.B-1-β was nearly 710 KDa. The monosaccharides´ composition of Fr.B-1-β was analized by HPLC, and glucose was the dominent component, and fucose and galactose were also detected. The result of amino acid analysis was that glutamic acid and alanine were detected to a significant level, and cysteine was not detected.
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