干热法及大分子拥挤体系制备的共价复合物的物化性质

Physicochemical Properties of Covalent Conjugates Prepared in Macromolecular Crowding Environment or via Dry-Heating Method

通过干热法和大分子拥挤体系分别制备大豆7S球蛋白-葡聚糖共价复合物,讨论不同反应体系制备的产物的物化性质差异.根据糖基化产物在7S等电点(p H=4.8)和中性条件(p H=6.5)下的溶解性将其分成两组分,对其接枝度、蛋白质二级结构、内置荧光和浊度进行分析.结果表明:在大分子拥挤环境下,7S在液相环境中发生了一定程度的水解,生成小分子的肽链,有利于多糖的共价接入;MC48(p H=4.8时制得,大分子拥挤体系)中主要是接枝程度较高的糖基化产物,MC65(p H=6.5时制得,大分子拥挤体系)中含有的糖基化产物接枝度较低,且程度不均匀;干热法制备得到的DH48(p H=4.8时制得)和DH65(p H=6.5时制得)接枝度较低,差异性不及大分子拥挤环境显著.SDSPAGE、圆二色光谱、内置荧光分析结果表明,大分子拥挤环境下制得的MC48和MC65物化性质差异显著,而干热法制得的DH48和DH65的物化性质差异不明显.

Two kinds of β-conglycinin-dextran conjugates were prepared respectively in the macromolecular crowding environment or via the dry-heating method,and then a comparison was made in their physicochemical property. On the basis of the solubility of glycation products at the isoelectric point of β-conglycinin( p H = 4. 8) or under the neutral condition( p H = 6. 5),the products were separated into two components,and then a discussion was conducted about the graft degree,secondary structure,internal fluorescence and turbidity of the two components.The results show that( 1) β-conglycinin in the macromolecular crowding and liquid phase environment is hydrolyzed to a certain degree,with small peptide chains being produced,which is beneficial to the covalent access of polysaccharide;( 2) MC48 obtained at p H4. 8 in the macromolecular crowding environment,is mainly the glycation product of high graft degree,while MC65 obtained at p H6. 5 in the macromolecular crowding environment,contains the glycation products of both low and uneven graft degree; and( 3) DH48 and DH65 obtained respectively at p H4. 8 and p H6. 5 via the dry-heating method,are of low graft degree,and their difference is less significant than that in the macromolecular crowding environment. Moreover,it is found from SDA-PAGE,CD and intrinsic fluorescence emission spectra that there exists a significant difference in physicochemical property between MC48 and MC65,while an insignificant difference between DH48 and DH65.