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投稿时间：2023-01-04
投稿时间：2023-01-04
中文摘要: 采用不同浓度的2，2′-盐酸脒基丙烷[2，2′-azobis（2-amidinopropane），AAPH]有氧热分解产生的过氧自由基氧化花生球蛋白，研究AAPH 氧化对花生球蛋白分子结构及聚集行为的影响。结果显示：随着AAPH 浓度的增加，花生球蛋白表示浊度的吸光度由0.20±0.01 增加至0.44±0.01，平均粒径从（153.94±3.31）nm 增加到（196.80±3.06）nm，而游离巯基含量从（14.62±0.08）μmol/g 下降到（7.77±0.25）μmol/g，Zeta 电位绝对值从（24.17±0.06）mV 下降到（15.93±0.05）mV。对荧光最大发射波长的研究表明，在AAPH 浓度为0～1 mmol/L 时，内源荧光最大荧光峰位红移，在AAPH 浓度为5～15 mmol/L 时，内源荧光最大荧光峰位蓝移。过氧自由基氧化导致花生球蛋白α-螺旋结构含量下降，β-折叠和无规则卷曲含量上升，呈现出α-螺旋向β-折叠和无规则卷曲转化的趋势。扫描电镜观察结果显示，花生球蛋白经过氧自由基氧化后，蛋白由聚集紧实逐渐变得发散，浓度从10 mmol/L 升高到15 mmol/L 时，花生球蛋白表面形态变疏松，孔隙显著增大。因此，AAPH 适度氧化可以通过改变花生球蛋白的结构影响其聚集行为，特别是浓度为5～10 mmol/L 时有利于花生球蛋白的聚集。
Abstract:Arachin was oxidized by peroxide free radicals derived from aerobic thermal decomposition of 2，2′-azobis（2-amidinopropane）（AAPH）at different concentrations，and the effects of AAPH oxidation on the molecular structure and aggregation behavior of arachin were investigated.The results showed that with the increase of AAPH concentration，the absorbance representing turbidity of arachin increased from 0.20±0.01 to 0.44±0.01，the average particle size increased from（153.94±3.31）nm to（196.80±3.06）nm，and the content of free sulfhydryl group decreased from（14.62±0.08）μmol/g to（7.77±0.25）μmol/g.The absolute value of Zeta potential decreased from（24.17±0.06）mV to (15.93±0.05）mV.The study on the maximum emission wavelength of fluorescence showed that when the AAPH concentration was 0-1 mmol/L，the maximum fluorescence peak of intrinsic fluorescence red-shifted，and when the AAPH concentration was 5-15 mmol/L，the maximum fluorescence peak of intrinsic fluorescence blue-shifted.Peroxide free radical oxidation resulted in the decrease of α-helix content of arachin but an increase of β-sheet and random coil，showing a trend of transformation from α-helix to β-sheet and random coil.The scanning electron microscopy results showed that after peroxide free radical oxidation，arachin gradually dispersed from a tightly aggregated state.Especially，when the concentration increased from 10 mmol/L to 15 mmol/L，the surface morphology of arachin became loose，and the pores increased significantly.Therefore，moderate oxidation by AAPH can affect the aggregation behavior of arachin by changing its structure，particularly at the concentrations of 5-10 mmol/L，which is conducive to the aggregation of arachin.
keywords: arachin peroxide radical oxidation secondary structure infrared spectrum aggregation behavior
文章编号：202407007 中图分类号： 文献标志码：
基金项目:国家自然科学基金项目（31901643）
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