不同分子质量葡聚糖对玉米醇溶蛋白糖基化产物结构和功能性的影响

采用湿热法将玉米醇溶蛋白（Zein）与不同分子质量（6、20、40、70 kDa）的葡聚糖（dextran，DX）制备成Zein-DX糖基化产物，探讨不同分子质量DX对Zein糖基化产物结构和功能性的影响。随着DX分子质量的增加，Zein-DX糖基化产物的接枝度和褐变强度降低，说明低分子质量DX更容易与Zein发生糖基化反应，且糖基化产物具有更高的溶解度和更低的表面疏水性。糖基化反应能够提高Zein的乳化活性（emulsifying activity index，EAI）和乳化稳定性（emulsifying stability index，ESI），随着DX分子质量的增加，Zein-DX糖基化产物的EAI逐渐降低，ESI逐渐增加。此外，高分子质量DX的共价结合能够使Zein的二级结构由有序的α-螺旋结构转变为无序的β-折叠和无规则卷曲结构，导致蛋白质构象变得更加灵活和松散。

Effect of Dextran with Different Molecular Masses on Structure and Functional Properties of Zein Glycosylation Products

Zein and dextran (DX) with different molecular masses (6, 20, 40 and 70 kDa) were prepared into zein-DX glycosylation products by a wet heating method in the present research. The purpose was to examine the effect of DX with different molecular masses on structural and functional properties of zein glycosylation products. As molecular mass of DX increased, the degree of graft and the browning intensity reduced, which indicated that DX with lower molecular mass was easier to react with zein to form glycosylation products with higher solubility and lower surface hydrophobicity. Glycosylation could improve the emulsifying activity index (EAI) and emulsifying stability index (ESI) of zein. With the increase in the molecular mass of DX, the EAI of zein-DX glycosylation products gradually decreased and the ESI gradually increased. Moreover, the covalent binding affinity of DX with high molecular mass could lead to the transformation of the ordered α-helix structure to the unordered β-sheet and random coil structure, which resulted in more flexible and looser protein conformation.