發(fā)布時(shí)間：2019-06-11 21:47

【摘要】：生物聚合物復(fù)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(diǎn),近年來(lái)作為石油基塑料的替代品備受關(guān)注,大豆蛋白因其高蛋白含量和高營(yíng)養(yǎng)價(jià)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(zhì)。傅里葉變換紅外光譜是研究物質(zhì)結(jié)構(gòu)信息、分子相互作用及分子動(dòng)力學(xué)的有效手段,但對(duì)蛋白而言,酰胺Ⅰ帶中不同的二級(jí)結(jié)構(gòu)吸收峰嚴(yán)重重疊,因此普通的一維光譜很難觀測(cè)到其變化。二維相關(guān)光譜(two-dimensional correlation spectroscopy,2DCOS)將原始特征吸收譜帶光譜信號(hào)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(dòng)作用下譜帶強(qiáng)度變化的順序,這在分析分子結(jié)構(gòu)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(jié)合2DCOS與擾動(dòng)相關(guān)移動(dòng)窗二維(perturbation-correlation moving-window two-dimensional,PCMW2D)技術(shù)研究了復(fù)合膜中氫鍵相互作用對(duì)蛋白質(zhì)二級(jí)結(jié)構(gòu)的影響并進(jìn)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(dǎo)致酰胺譜帶吸收強(qiáng)度增加,并呈現(xiàn)出“S”型曲線,強(qiáng)度突躍發(fā)生在甘油濃度10-30%范圍內(nèi)。PCMW2D將甘油濃度分為兩部分區(qū)間。對(duì)系列SPI膜的酰胺Ⅰ帶和Ⅱ帶進(jìn)行2DCOS分析表明,甘油與SPI間的氫鍵相互作用導(dǎo)致了蛋白質(zhì)二級(jí)結(jié)構(gòu)發(fā)生變化。當(dāng)甘油加入時(shí),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(nèi),平行β-折疊轉(zhuǎn)變?yōu)棣?轉(zhuǎn)角;20-35%范圍內(nèi),反平行β-折疊向β-轉(zhuǎn)角轉(zhuǎn)變;35-60%范圍內(nèi),β-折疊首先轉(zhuǎn)化為過(guò)渡態(tài)結(jié)構(gòu),隨后與β-轉(zhuǎn)角均向無(wú)規(guī)卷曲轉(zhuǎn)變。2DCOS結(jié)果表明,SPI膜中二級(jí)結(jié)構(gòu)逐漸從有序結(jié)構(gòu)向無(wú)序和較無(wú)序結(jié)構(gòu)轉(zhuǎn)變,顯著提高了 SPI膜的塑性。本論文同樣采用了ATR/FTIR結(jié)合2DCOS與PCMW2D研究了 SPI/殼聚糖(CHT)復(fù)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(guò)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(jí)結(jié)構(gòu)組分發(fā)生變化且以70%為界限將其變化過(guò)程分為兩部分。2DCOS分析表明CHT濃度50-70%范圍內(nèi),反平行β-折疊結(jié)構(gòu)發(fā)生彎曲而向β-轉(zhuǎn)角結(jié)構(gòu)轉(zhuǎn)變,但這種轉(zhuǎn)變趨勢(shì)很弱。在CHT濃度70-95%范圍內(nèi),較無(wú)序的β-轉(zhuǎn)角結(jié)構(gòu)向有序的反平行β-折疊結(jié)構(gòu)逐漸轉(zhuǎn)變,使SPI共混結(jié)構(gòu)中有序結(jié)構(gòu)增加。在70-95%范圍內(nèi)復(fù)合膜中CHT為主要組分,CHT線性大分子鏈與SPI肽鏈結(jié)構(gòu)并非無(wú)序排列,而更可能以規(guī)整的交叉網(wǎng)絡(luò)結(jié)構(gòu)排列,因此形成的共混結(jié)構(gòu)中SPI中規(guī)整的蛋白二級(jí)結(jié)構(gòu)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(hào)：2497473