Structure and chain conformation of a neutral intracellular heteropolysaccharide from mycelium of Paecilomyces cicadae

摘要

A neutral heteropolysaccharide (PCIPS2) was isolated and purified from mycelium ofPaecilomyces cicadae which was investigated to be mainly composed of D-mannose, L-rhamnose, 3-O-methyl-D-galactose, D-glucose and ID-galactose with a molar ratio of 47.9:3.1: 6.4:0.9:0.8. It had a backbone of 1A-linked alpha-L-Rhap residues and 1,6-linked alpha-D-Manp residues with branches at O-3 of alpha-D-Manp residues. Its side chain was comprised of minor terminal beta-D-glucose and 1A-linked alpha-3-O-Me-D Galp residues terminated by alpha-D-galactose. Furthermore, its chain information on the values of weight-average molar mass (M-w), root mean square radius (< S >)(z)(1/2)), hydrodynamic radius (R-h) and intrinsic viscosity ([eta]) for PCIPS2 were analyzed to be 3.09 x 10(4) g/mol, 7.8 nm, 3.6 nm and 8.5 mL/g, respectively. The structural exponent alpha of 0.57 indicated that PCIPS2 existed as a flexible chain conformation with a coil-like structure in 0.1 M NaNO3 at 25 degrees C. In terms of known theory for worm-like chains, the model parameters for PCIPS2 were as following: molar mass per unit contour length (M-L) = 379 nm(-1), persistence length (q) = 0.74 nm and hydrodynamic diameter of cylinder (d) = 0.82 nm, which were further evidenced by atomic force microscopy (AFM). (C) 2015 Elsevier Ltd. All rights reserved.