Unperturbed dimensions of Carrageenans in different salt solutions

被引:22
作者
Marcelo, G [1 ]
Saiz, E [1 ]
Tarazona, MP [1 ]
机构
[1] Univ Alcala de Henares, Dept Quim Fis, E-28871 Alcala De Henares, Madrid, Spain
关键词
unperturbed dimensions; SEC-MALS; Carrageenan;
D O I
10.1016/j.bpc.2004.09.005
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Commercial samples of kappa-, iota -, and lambda-carrageenans were studied by means of Size Exclusion Chromatography with dual detection, i.e. employing a Refractive Index (concentration sensitive) and Multiangle Light Scattering (size sensitive) detectors. The eluent was water containing 0.1 M concentration of different ionic salts, namely LiCl, NaCl, KCl and NaI, with the exception of kappa-carrageenan that aggregates in presence of KCl. Molecular weight distributions and averages, coefficients of the scaling law of molecular dimensions and unperturbed dimensions were thus obtained from a single polydisperse sample of each polymer. Measurements were performed at 25 degreesC and all the systems were above theta conditions with values of the q exponent of the scaling law ranging from 0.51 to 0.59. Extrapolation to unperturbed conditions provides values of the characteristic ratio C-N=56+/-1 and 40+/-5 respectively for lambda- and iota-carrageenans regardless of the ionic salt employed. However, kappa-carrageenan gives C-N=31, 35 and 59, respectively, in presence of LiCl, NaCl and NaI, which clearly indicates that this polymer behaves on a different way in presence of NaI than with the other two salts. A tentative explanation of this difference is provided. (C) 2004 Elsevier B.V. All rights reserved.
引用
收藏
页码:201 / 208
页数:8
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