【作者】 程海涛；

【导师】 李军生；

【作者基本信息】 广西工学院 ， 生物化工， 2010， 硕士

【摘要】 蛋白质同时含有亲水性和疏水性基团,理论上应该具有理想的表面活性性能。然而,由于极性或非极性氨基酸在每一种蛋白质肽链中分布的不规则性或特异性,以及蛋白质空间结构和空间结构作用力如二硫键的影响,绝大多数天然蛋白质因疏水性基团被包裹在致密稳固的蛋白质分子内部而无法表现出其表面活性性能。另外由于蚕丝蛋白结构中结晶区与非结晶区的影响,蚕丝蛋白根本不能溶于水。为了研究蚕丝蛋白表面活性性能,本文首先利用超声波、盐溶方法制得水溶性蚕丝蛋白,使蚕丝蛋白表面活性性能研究成为可能。研究了另一种使蚕丝蛋白溶于水的方法:利用物理(温度压力)与化学(催化剂硫酸)结合的手段,溶解废茧、废丝,研究了溶解创新工艺与溶解液的表面活性。为了进一步优化蚕丝蛋白表面活性性能,我们利用化学修饰的手段在蚕丝蛋白氨基酸残基化学活性位点上引入长碳链基团,进行了酰化修饰。得出以下结论:1、建立了新的水溶性丝胶蛋白和丝素蛋白制备工艺,研究了其表面活性性能。废茧、废丝在除杂精选的基础上,利用90倍体积水、超声波协同作用15min,在95℃作用25min,经过冷冻干燥,制备了丝胶蛋白。制备丝胶蛋白后的废茧、废丝在沸腾的5mol/L氯化钙溶液中溶解,盐溶时间15min、液固比8:1,再经过6小时加压脱盐,利用冷冻干燥,制备了丝素蛋白。SDS-PAGE电泳表明制备的丝胶蛋白分子量具有连续性,丝素蛋白的分子量相对集中。丝胶、丝素表现出了不同程度的表面活性。2、以废丝、废茧为原料,在一定温度、压力等外力作用下,硫酸做催化使废茧、废丝溶解,创新了蚕丝溶解工艺,研究了溶解产物(多肽)溶液的表面活性性能。溶解工艺:硫酸浓度26%,时间20min,温度(压力)120℃(0.2MPa),液固比110。在最优条件下进行验证性实验,测得的溶解度为99.99 %。3、蚕丝水解液表面活性性能:CMC=0.6g/L,此时表面张力为29.5 mN/m;蚕丝水解液的乳化性接近90%;蚕丝水解液乳化稳定性随浓度变化比较平缓;有一定的发泡力和泡沫稳定性,且在硬水与软水中的发泡力和泡沫稳定性相当,因此具有一定的抗硬水的能力;HLB值为11时乳化性能最好,说明蚕丝水解液是具有一定亲油性的表面活性剂;润湿时间为74.5秒;去污力达到55%。4、利用化学修饰的手段对水解产物进行酰化修饰,引入了长链基团,在此基础上研究了修饰产物的表面活性性能。化学修饰最佳工艺:多肽15 mL,椰子油酰氯3 mL,pH为12,温度为55℃,丙酮为7 mL。在此条件下的平均转化率92.5%。表面活性性能:CMC=0.8g/L,此时表面张力为27.6 mN/m;修饰产品在CMC浓度下的乳化性接近100%;修饰产物乳化稳定性随浓度变化很小;有很好的发泡力和泡沫稳定性,且在硬水与软水中的发泡力和泡沫稳定性相当。5、在测定溶液表面张力的基础上,研究了N-椰油酰基多肽的胶束形成的标准热力学函数、分子吸附动力学及其影响因素。以期待对学术、实际应用提供参考价值。利用盐溶的方法得到的水溶性蚕丝蛋白,其表面活性性能表现的不是十分良好。利用高温、高压物理条件以及硫酸作为催化剂得到的水溶性蚕丝蛋白,在表面活性性能方面有一定提高但是还存在很多缺陷。经过化学修饰后的产物表现出良好而全面的表面活性性能,有效改善了蚕丝蛋白的表面活性。为有效利用废茧、废丝,制备安全无毒、绿色的蛋白质表面活性剂提供了有效途径。更多还原

【Abstract】 Proteins composed of polar and nonpolar amino acid connected by peptide bonds, should be a kind of ideal surfactants. However, because of particular structure of protein and coiling fold of polypeptide chain, most of proteins can’t show their surface active properties as the nonpolar groups of proteins are covered in the compact and steady protein molecules. We use salt dissolving, hydrolysis, chemical modification method to study the surface properties of silk protein. Conclusion is listed below :1.This paper established the preparation technology of the sericin and silk fibroin. The best optimized conditions of the sericin: V(water):V(silk waste)=90:1, ultrasonic time 15min, Temperature 95℃, temperature time 25min. The silk sericin protein was prepared using the freeze-drying technology. The best optimized conditions of the silk fibroin protein: V(CaCl2, 5mol/L):V(silk waste)=8:1, the salt dissolve time 15min, desalting time(pressure) 6h. The silk fibroin protein was prepared using the freeze-drying technology. SDS-PAGE gel electrophoresis showed that the molecular weight of the silk sericin protein is continuous and the molecular weight of the silk fibroin protein is single. silk sericin protein and the silk fibroin protein showed different degree of surface activity.2.Silk protein hydrolysis was studied in this paper under the condition of external force. The best technological conditions: hydrolysis temperature 120℃(0.2MPa), the concentration of sulphuric acid 26%, time 20min, the liquid-solid ratio110:1, yield 99.99%.3 . Silk hydrolysate active surface properties:CMC0.6g/L,γ29.5 mN/m, the emulsification 90%, emulsion stability 85%, foam ability 81%, foam stability 85%, HLB 11, Wetting time 74.5s, detergency 55%.4.Silk protein chemical modification process: dodecanoyl chloride 3mL, composite amino acids15mL, acetone 7mL, pH12,reaction temperature55℃, reaction time 4h. The average production of N- dodecanoyl composite amino acids is 92.5% under the optimum synthesis conditions. It shows good surfactant properties. CMC0.8g/L,γ27.6.5mN/m, the emulsification 90%, emulsion stability 85%, foam ability 81%, foam stability 85%, HLB 11, Wetting time 74.5s, detergency 55%.5.We study the formation of molecular thermodynamic functions, standard of adsorption dynamics and its influencing factors.The silk protein that is prepared using the method of salt soluble is not very good in active surface properties. And the silk protein that is prepared using the method of hydrolysis has a certain increase in surface properties, but also has many defects. The silk proteins after chemical modification shows good and overall surface properties, effectively improves the surface properties of silk protein. This method provides an effective way of effectively using waste cocoons, discard silk, non-toxic, and preparing of green protein surfactant.更多还原