卵转铁蛋白和乳铁蛋白的热处理稳定性的比较研究

黎庆; 景浩

doi:10.13386/j.issn1002-0306.2016.19.011

卵转铁蛋白和乳铁蛋白的热处理稳定性的比较研究

黎庆,
景浩

Comparison of thermal stability of ovotransferrin and lactoferrin

LI Qing,
JING Hao

摘要

摘要: 卵转铁蛋白（Ovotransferrin,OVT）和乳铁蛋白（Lactoferrin,LF）经不同温度（50⁹0℃）处理后,通过圆二色性分析比较其二级结构的变化,紫外吸收和表面疏水性分析比较其空间构象的变化,SDS-PAGE分析比较其分子的聚集,溶解度分析比较其功能的变化。结果表明,50⁶0℃时,OVT和LF的理化特性均无明显变化。70℃时,OVT和LF的紫外吸光值均明显增大;80⁹0℃时,OVT的紫外吸光值不再进一步增大,而LF的进一步逐渐增大。70⁹0℃时,OVT和LF的表面疏水性指数均明显增大;LF的表面疏水性指数远大于OVT的,但OVT的增大程度较LF的更大。70⁹0℃时,OVT和LF的α-螺旋含量均明显降低,β-折叠和无规卷曲含量均明显升高,且OVT的二级结构组分的变化程度较LF的更大。70⁹0℃时,OVT和LF的SDS-PAGE图谱中的主要蛋白条带密度均明显降低;相同温度下,OVT的降低程度较LF的更大。70⁹0℃时,OVT和LF的溶解度均明显降低;相同温度下,OVT的降低程度较LF的更大。总之,OVT和LF的结构和功能在加热时均发生改变,但OVT的变化程度较LF的更大。

Abstract: OVT and LF were heated at different temperatures of 50 ~ 90 ℃,and changes of their secondary structures,spatial conformation,and solubility were analyzed by circular dichroism( CD),UV absorbance,surface hydrophobicity,and turbidity / solubility tests,respectively. Protein aggregation was assessed by SDS- PAGE.Results showed that no change was observed for physicochemical properties of OVT and LF at 50 ~ 60 ℃.Significant increase of UV absorbance was observed for both LF and OVT at 70 ℃; further increase was observed for LF but not for OVT at 80 ~90 ℃. Significant increase of surface hydrophobicity index was observed for LF and OVT at 70~90 ℃.The surface hydrophobicity index of LF was higher than that of OVT,while the extents of increase were higher for OVT than LF. Decreased percentages of α- helix and increased percentages of β- sheet and random coil were observed for both LF and OVT at 70~90 ℃,but the extents of change were higher for OVT than LF.The band densities and solubility of OVT and LF were decreased at 70~90 ℃,but the extents of decrease were higher for OVT than LF at the same temperatures. In conclusion,changes were observed of structures and functional characteristic for OVT and LF after heating treatment,while the extents of change were higher for OVT than LF.