A Sulfated Polysaccharide Produced by an Arthrobacter Species

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Abstract
A new sulfated polysaccharide was isolated from the culture supernatant of a strain of Arthrobacter sp. The polysaccharide purified with quaternary ammonium salts consists of D-galactose, D-glucose, sulfate, phosphorus, glucosamine, muramic acid, alanine, glutamic acid, glycine, and LL-diaminopimelic acid in a molar ratio of 56 : 9.0 : 68 : 6.4 : 2.0 : 1.1 : 2.1 : 1.0 : 1.2 : 1.2. The presence of the two amino sugars and four amino acids suggests that the polysaccharide, which is principally a galactan sulfate, contains small amounts of so-called peptidoglycan and that it is derived from the bacterial cell-wall polysaccharide. Gel filtration indicates the heterogeneity of the purified polysaccharide in its peptidoglycan content and molecular size. The molecular weight of its major portion was estimated to be 2.3 × 104 by gel filtration. The fractions GS-I and GS-II, and GS-4M and GS-5M, which were obtained by fractionation of the polysaccharide on Sephacryl S-200 and Dowex 1-X2 (Cl− form), respectively, gave almost the same chemical composition as the original polysaccharide, except in the peptidoglycan content, indicating that this polysaccharide is a series of complexes composed of essentially equal, sulfated polysaccharide chains and peptidoglycan fragments in their various ratios. The polysaccharide has [a]D −36° and is composed predominantly of β-glycosidic linkages, as judged from its specific optical rotation (−37°) and the infrared absorption (885 cm−1) of its desulfated material. It exhibits a potent antithrombin activity (ID50, 0.82 μg/ml). A possible partial structure of the polysaccharide is also discussed, based on the results of periodate oxidation, Smith degradation, and alkali treatment.