不同直链/支链比的玉米淀粉分子质量及其构象

Molecular Mass and Conformation of Corn Starches with Ddifferent Amylose/Amylopectin Ratios

采用凝胶渗透色谱(GPC)和十八角度激光光散射(MALLS)技术,以二甲基亚砜为流动相测定蜡质玉米淀粉、普通玉米淀粉、直链/支链比1:1的高直链玉米淀粉(G50)、直链/支链比4:1的高直链玉米淀粉(G80)的分子质量及其分布以及在二甲基亚砜(DMSO)溶液中的均方根旋转半径和构象。结果表明:分子质量最大的是蜡质玉米淀粉,其重均分子质量达到了1.416×108g/mol,其次是普通玉米淀粉2.744×107g/mol与G501.026×107g/mol,最小的是G80的3.992×106g/mol;均方根旋转半径也是随着直链淀粉含量的增加依次减小;蜡质玉米淀粉在DMSO溶液中的构象是较为紧密的无规则卷曲型,其他3种玉米淀粉的构象均为球型。

The determination of molecular mass,molecular mass distribution,mean square radius of gyration and conformation using gel permeation chromatography coupled with multi-angle laser light scattering （GPC-MALLS） with refractive index detector with DMSO as the mobile phase was carried out for waxy,common,G50 （with 50% amylase content） and G80 （with 80% amylase content） corn starches. The results showed that the weight-average molecular masses （Mw） of waxy,normal,G50 and G80 corn starches were 1.416 × 108,2.744 × 107,1.026 × 107,3.992 × 106 g/mol,respectively. Similarly,higher-amylose corn starch had smaller mean square radius of gyration. The conformation of waxy corn starch was compact random coil and the three others were compact globular structure in DMSO.