Abstract: In this study, ESP-1A, an exopolysaccharide isolated and purified from the fermentation broth of cultured Cordyceps sinensis fungus Cs-HK1 was used to study the effects of temperature, metal ion (Ca2+), denaturing agent (urea) and chemical modifier (congo red) on its confirmation by means of ultraviolet (UV) spectroscopy and circular dichroism (CD) spectroscopy. The results indicated that congo red reaction revealed that EPS-1A was a random coil chain conformation. External conditions could not alter the random coil chain conformation of EPS-1A in aqueous solutions, but influence the inter- and intra-molecular hydrogen bond interactions of polysaccharide molecules in some extent so that EPS-1A became more loose and disordered.

Key words: Cordyceps sinensis, exopolysaccharides, conformation, ultraviolet spectroscopy, circular dichrosim spectroscopy