熔融尿素法提取羊毛角蛋白机制

Mechanism of Extracting Wool Keratin by Molten Urea Method

为了探明羊毛角蛋白在熔融尿素中溶解的原理,首先采用SDS-PAGE电泳法测定了溶解羊毛角蛋白的分子质量。其次分别使用香草醛、香草醇、香草酸、乙酰香草醛、甲酰香草酸、4-乙酰-3-甲酰芥子酸、水杨酰苯胺、3,3-二羟基二苯二硫醚、苯胺、酪氨酸等标准化合物替代羊毛角蛋白中的官能团及化学键,与尿素在150℃下反应20 min,经乙酸乙酯分液3次,有机层脱水浓缩,丙酮溶解,GC-MS分析;水层冷冻干燥,乙酰化,浓缩,GC-MS分析。结果显示,溶解羊毛角蛋白的分子质量为75 ku,以较高分子状态存在。醛基脱离,酯键只脱离乙酰基,羧基脱离或者与尿素结合,醇羟基和氨基与尿素结合,肽键、二硫键不断裂。羊毛在熔融尿素中溶解是氢键的断裂、官能团的脱离、尿素向官能团结合等几个主要途径来完成的,羊毛角蛋白的一级结构没有被破坏,仍然以较高分子状态存在。酪氨酸的氨基和羧基均跟尿素反应形成环化结构,才能溶于有机溶剂中,并从GC-MS的分析中能检测。所有标准化合物与尿素反应产物的水层中,既没有原料转变的化合物,也没有原料本身,有必要改善试验方法进行进一步的研究。

In order to find out the principle of wool keratin dissolved in molten urea,SDS-PAGE method was used to determine the molecular weight of dissolved wool keratin firstly.Secondly,standard compounds such as vanillin,vanillyl alcohol,vanillic acid,acetyl vanillin,formyl vanillic acid,4-acetyl-3-formyl succinic acid,salicylanilide,3,3-dihydroxydiphenyl disulfide,aniline,tyramine acid were used to substitute the functional group and chemical bond in wool keratin,respectively,and react with urea at 150℃for 20 min,separated 3 times with ethyl acetate,dehydrated and concentrated for the organic layer,dissolved with acetone,and analyzed by GC-MS.Aqueous layer was freeze-dried,ethylationed,concentrated for GC-MS analysis.The result showed that,the wool keratin with high molecular weight,75 ku,still maintained a high molecular state.The aldehyde group was detached,the ester bond was only deacetylated,the carboxyl group was detached or bound to urea,the alcoholic hydroxyl group and the amino group were combined with urea,and the peptide bond and the disulfide bond were not broken.Main approaches of the dissolution mechanism of wool in molten urea were hydrogen bond cleavage,functional group detachment,urea bonding to functional group,etc.The primary structure of wool keratin was not destroyed and still maintained a high molecular state.The amino and carboxyl groups of tyrosine reacted with urea to form a cyclized structure,which could be dissolved in an organic solvent and could be detected from the analysis of GC-MS.There were neither compounds that were converted from raw materials,nor the raw materials themselves in the aqueous layer of all standard compounds and urea reaction products,so improvement of experimental method was needed for further research.