【摘要】：生物聚合物復合材料具有良好的生物相容性、可降解性及低成本等優(yōu)點,近年來作為石油基塑料的替代品備受關注,大豆蛋白因其高蛋白含量和高營養(yǎng)價值脫穎而出。在大豆蛋白基材料中添加活性成分或與功能活性聚合物共混可顯著改善其性質。傅里葉變換紅外光譜是研究物質結構信息、分子相互作用及分子動力學的有效手段,但對蛋白而言,酰胺Ⅰ帶中不同的二級結構吸收峰嚴重重疊,因此普通的一維光譜很難觀測到其變化。二維相關光譜(two-dimensional correlation spectroscopy,2DCOS)將原始特征吸收譜帶光譜信號拓展到二維空間,顯著提高了光譜分辨率且有效地分離了重疊譜帶。此外,2DCOS可以判斷出擾動作用下譜帶強度變化的順序,這在分析分子結構變化及分子間相互作用等方面尤為重要。本文首先制備了不同SPI與甘油比例的蛋白基生物塑料膜,并采用衰減全反射/傅里葉變化紅外光譜(attenuated total reflectance/Fourier transform infrared,ATR/FTIR)結合2DCOS與擾動相關移動窗二維(perturbation-correlation moving-window two-dimensional,PCMW2D)技術研究了復合膜中氫鍵相互作用對蛋白質二級結構的影響并進一步研究增塑作用。ATR/FTIR表明,大豆分離蛋白(SPI)與甘油間存在的氫鍵相互作用導致酰胺譜帶吸收強度增加,并呈現(xiàn)出“S”型曲線,強度突躍發(fā)生在甘油濃度10-30%范圍內。PCMW2D將甘油濃度分為兩部分區(qū)間。對系列SPI膜的酰胺Ⅰ帶和Ⅱ帶進行2DCOS分析表明,甘油與SPI間的氫鍵相互作用導致了蛋白質二級結構發(fā)生變化。當甘油加入時,甘油小分子插入到蛋白的β片層間,SPI肽鏈骨架間氫鍵逐漸被甘油與SPI間新的氫鍵相互所代替。在0-20%濃度范圍內,平行β-折疊轉變?yōu)棣?轉角;20-35%范圍內,反平行β-折疊向β-轉角轉變;35-60%范圍內,β-折疊首先轉化為過渡態(tài)結構,隨后與β-轉角均向無規(guī)卷曲轉變。2DCOS結果表明,SPI膜中二級結構逐漸從有序結構向無序和較無序結構轉變,顯著提高了 SPI膜的塑性。本論文同樣采用了ATR/FTIR結合2DCOS與PCMW2D研究了 SPI/殼聚糖(CHT)復合膜間相互作用。首先,采用ATR/FTIR及SEM考察了共混材料的均勻性,并通過ATR/FTIR系列光譜圖中酰胺Ⅰ帶吸光度隨CHT濃度增加而增加確定二者間存在相互作用。其次,PCMW2D分析中,相互作用下酰胺Ⅰ帶中二級結構組分發(fā)生變化且以70%為界限將其變化過程分為兩部分。2DCOS分析表明CHT濃度50-70%范圍內,反平行β-折疊結構發(fā)生彎曲而向β-轉角結構轉變,但這種轉變趨勢很弱。在CHT濃度70-95%范圍內,較無序的β-轉角結構向有序的反平行β-折疊結構逐漸轉變,使SPI共混結構中有序結構增加。在70-95%范圍內復合膜中CHT為主要組分,CHT線性大分子鏈與SPI肽鏈結構并非無序排列,而更可能以規(guī)整的交叉網(wǎng)絡結構排列,因此形成的共混結構中SPI中規(guī)整的蛋白二級結構為主要成分。
[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，

本文編號：2497473