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Three groups of exopolysaccharides (EPSs) (designated as Fr-I, Fr-II, and Fr-III) were isolated from the culture filtrates of Paecilomyces sinclairii by gel filtration chromatography on Sepharose CL-4B. Their molecular characteristics were examined by multi-angle laser light scattering (MALLS) connected online to a size exclusion chromatography (SEC) and refractive index (RI) detector system. The weight-average molar mass of Fr-I, Fr-II, and Fr- III of EPSs were determined to be 1.540×106, 6.302×104, and 9.389×104 g/mol, respectively. All three EPSs showed a fairly low polydispersity indice, ranging from 1.008 to 1.059 (nearly monodisperse behavior), and showed different carbohydrates and amino acids compositions; all fractions of EPSs consisted of mainly cystine, valine, and arginine in the protein moiety, and mainly ribose, galactose, and glucose in the carbohydrate moiety. The determination of gyration radii of the EPSs in SEC/MALLS analysis revealed the molecular shape of the Fr- I to be a rod-like structure, whereas the Fr-II and Fr-III had a random-coil structure in an aqueous solution.
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