二维相关红外光谱研究大豆分离蛋白复合物的相互作用
发布时间：2019-06-11 21:47
【摘要】：生物聚合物复合材料具有良好的生物相容性、可降解性及低成本等优点,近年来作为石油基塑料的替代品备受关注,大豆蛋白因其高蛋白含量和高营养价值脱颖而出。在大豆蛋白基材料中添加活性成分或与功能活性聚合物共混可显著改善其性质。傅里叶变换红外光谱是研究物质结构信息、分子相互作用及分子动力学的有效手段,但对蛋白而言,酰胺Ⅰ带中不同的二级结构吸收峰严重重叠,因此普通的一维光谱很难观测到其变化。二维相关光谱(two-dimensional correlation spectroscopy,2DCOS)将原始特征吸收谱带光谱信号拓展到二维空间,显著提高了光谱分辨率且有效地分离了重叠谱带。此外,2DCOS可以判断出扰动作用下谱带强度变化的顺序,这在分析分子结构变化及分子间相互作用等方面尤为重要。本文首先制备了不同SPI与甘油比例的蛋白基生物塑料膜,并采用衰减全反射/傅里叶变化红外光谱(attenuated total reflectance/Fourier transform infrared,ATR/FTIR)结合2DCOS与扰动相关移动窗二维(perturbation-correlation moving-window two-dimensional,PCMW2D)技术研究了复合膜中氢键相互作用对蛋白质二级结构的影响并进一步研究增塑作用。ATR/FTIR表明,大豆分离蛋白(SPI)与甘油间存在的氢键相互作用导致酰胺谱带吸收强度增加,并呈现出“S”型曲线,强度突跃发生在甘油浓度10-30%范围内。PCMW2D将甘油浓度分为两部分区间。对系列SPI膜的酰胺Ⅰ带和Ⅱ带进行2DCOS分析表明,甘油与SPI间的氢键相互作用导致了蛋白质二级结构发生变化。当甘油加入时,甘油小分子插入到蛋白的β片层间,SPI肽链骨架间氢键逐渐被甘油与SPI间新的氢键相互所代替。在0-20%浓度范围内,平行β-折叠转变为β-转角;20-35%范围内,反平行β-折叠向β-转角转变;35-60%范围内,β-折叠首先转化为过渡态结构,随后与β-转角均向无规卷曲转变。2DCOS结果表明,SPI膜中二级结构逐渐从有序结构向无序和较无序结构转变,显著提高了 SPI膜的塑性。本论文同样采用了ATR/FTIR结合2DCOS与PCMW2D研究了 SPI/壳聚糖(CHT)复合膜间相互作用。首先,采用ATR/FTIR及SEM考察了共混材料的均匀性,并通过ATR/FTIR系列光谱图中酰胺Ⅰ带吸光度随CHT浓度增加而增加确定二者间存在相互作用。其次,PCMW2D分析中,相互作用下酰胺Ⅰ带中二级结构组分发生变化且以70%为界限将其变化过程分为两部分。2DCOS分析表明CHT浓度50-70%范围内,反平行β-折叠结构发生弯曲而向β-转角结构转变,但这种转变趋势很弱。在CHT浓度70-95%范围内,较无序的β-转角结构向有序的反平行β-折叠结构逐渐转变,使SPI共混结构中有序结构增加。在70-95%范围内复合膜中CHT为主要组分,CHT线性大分子链与SPI肽链结构并非无序排列,而更可能以规整的交叉网络结构排列,因此形成的共混结构中SPI中规整的蛋白二级结构为主要成分。
[Abstract]:Biopolymer composites have many advantages, such as good biocompatibility, degradability and low cost. In recent years, soybean protein has attracted much attention as a substitute for petroleum-based plastics. Soybean protein stands out because of its high protein content and high nutritional value. The properties of soybean protein based materials can be significantly improved by adding active components or blending with functional active polymers. Fourier transform infrared spectroscopy (FTIR) is an effective method to study material structure information, molecular interaction and molecular dynamics, but for proteins, different secondary structure absorption peaks in amide I band overlap seriously, so it is difficult to observe its change in ordinary one-dimensional spectrum. Two-dimensional correlation spectroscopy (two-dimensional correlation spectroscopy,2DCOS) extends the spectral signal of the original characteristic absorption band to two-dimensional space, which significantly improves the spectral resolution and effectively separates the overlapping bands. In addition, 2DCOS can judge the order of spectral band intensity change under disturbance, which is particularly important in the analysis of molecular structure change and intermolecular interaction. In this paper, protein based biomaterials with different ratio of SPI to glycerol were prepared, and the effect of hydrogen bond interaction on protein secondary structure was studied by attenuated total reflection / Fourier transform infrared spectroscopy (attenuated total reflectance/Fourier transform infrared,ATR/FTIR) combined with 2DCOS and disturbance dependent moving window two dimensional (perturbation-correlation moving-window two-dimensional,PCMW2D) technique. ATR / FTIR showed that The hydrogen bond interaction between soybean protein isolate (SPI) and glycerol resulted in an increase in the absorption intensity of amide band, and showed an "S" curve. The intensity jump occurred in the range of 10 鈮，
本文编号：2497473
[Abstract]:Biopolymer composites have many advantages, such as good biocompatibility, degradability and low cost. In recent years, soybean protein has attracted much attention as a substitute for petroleum-based plastics. Soybean protein stands out because of its high protein content and high nutritional value. The properties of soybean protein based materials can be significantly improved by adding active components or blending with functional active polymers. Fourier transform infrared spectroscopy (FTIR) is an effective method to study material structure information, molecular interaction and molecular dynamics, but for proteins, different secondary structure absorption peaks in amide I band overlap seriously, so it is difficult to observe its change in ordinary one-dimensional spectrum. Two-dimensional correlation spectroscopy (two-dimensional correlation spectroscopy,2DCOS) extends the spectral signal of the original characteristic absorption band to two-dimensional space, which significantly improves the spectral resolution and effectively separates the overlapping bands. In addition, 2DCOS can judge the order of spectral band intensity change under disturbance, which is particularly important in the analysis of molecular structure change and intermolecular interaction. In this paper, protein based biomaterials with different ratio of SPI to glycerol were prepared, and the effect of hydrogen bond interaction on protein secondary structure was studied by attenuated total reflection / Fourier transform infrared spectroscopy (attenuated total reflectance/Fourier transform infrared,ATR/FTIR) combined with 2DCOS and disturbance dependent moving window two dimensional (perturbation-correlation moving-window two-dimensional,PCMW2D) technique. ATR / FTIR showed that The hydrogen bond interaction between soybean protein isolate (SPI) and glycerol resulted in an increase in the absorption intensity of amide band, and showed an "S" curve. The intensity jump occurred in the range of 10 鈮，
本文编号：2497473
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