title: Effects of excluded volume and polydispersity on solution properties of lentinan in 0.1 M NaOH solution.
abstract: Seven lentinan fractions of various weight-average molecular weights (M(w)), ranging from 1.45 x 10(5) to 1.13 x 10(6) g mol(-1) were investigated by static light scattering and viscometry in 0.1M NaOH solution at 25 degrees C. The intrinsic viscosity [eta] - M(w) and radius of gyration s(2)(z) (1/2) - M(w) relationships for lentinan in 0.1M NaOH solution were found to be represented by [eta] = 5.1 x 10(-3)M(w) (0.81) cm(3) g(-1) and s(2)(z) (1/2) = 2.3 x 10(-1)M(w) (0.58) nm, respectively. Focusing on the effects of the M(w) polydispersity with the Schulz-Zimm distribution function, the data of M(w), s(2)(z) (1/2), and [eta] was analyzed on the basis of the Yoshizaki-Nitta-Yamakawa theory for the unperturbed helical wormlike chain combined with the quasi-two-parameter (QTP) theory for excluded-volume effects. The persistence length, molecular weight per unit contour length, and the excluded-volume strength were determined roughly to be 6.2 nm, 980 nm(-1), and 0.1, respectively. Compared with the theoretical value calculated by the Monte Carlo model, the persistence length is longer than that of the single (1 --> 3)-beta-(D)-glucan chain. The results revealed that lentinan exists as single-stranded flexible chains in 0.1M NaOH solution with a certain degree of expansion due to the electrostatic repulsion from the interaction between the OH(-) anions and lentinan molecules.
authors.affiliation: Department of Chemistry, Wuhan University, Wuhan 430072, China.
authors.forename: Xufeng
authors.initials: X
authors.lastname: Zhang
authors.forename: Juan
authors.initials: J
authors.lastname: Xu
authors.forename: Lina
authors.initials: L
authors.lastname: Zhang
mesh_terms: D002236:Carbohydrate Conformation; D003956:Dialysis; D005936:Glucans / Q000737:chemistry; D007700:Kinetics; D007912:Lentinan / Q000737:chemistry* / Q000302:isolation & purification; D008027:Light; D008956:Models, Chemical; D008968:Molecular Conformation; D008970:Molecular Weight; D009010:Monte Carlo Method; D012542:Scattering, Radiation; D012972:Sodium Hydroxide / Q000494:pharmacology*; D012996:Solutions; D013010:Sonication; D055672:Static Electricity; D014783:Viscosity / Q000187:drug effects; D014867:Water / Q000737:chemistry
chemical_list: D005936:Glucans; D012996:Solutions; D014867:Water; D007912:Lentinan; D012972:Sodium Hydroxide