丝素接枝含酪氨酸多肽对其酶促改性的影响

丝素中含约10%酪氨酸残基,但其可及度较低,影响了丝素蛋白的反应性。借助利用天然生物交联剂京尼平,将含酪氨酸多肽与丝素蛋白交联,提升酪氨酸酶催化丝素与外源氨基化合物接枝改性的效果;借助SDS-PAGE、FTIR和TG分析丝素分子量、结构与性能的变化,并评价酶催化ε-聚赖氨酸(ε-PL)在丝素表面接枝效率。研究表明,经京尼平处理后丝素蛋白的分子量增加,含酪氨酸多肽与丝素交联后,不仅使丝素膜材料热稳定性提升,也一定程度上增加了丝素蛋白膜材料机械性能,借助甲基橙比色法验证了接枝多肽能促进酪氨酸酶催化ε-PL在丝素表面接枝。基于京尼平法接枝含酪氨酸多肽为提高丝素的反应性提供了有效途径。     

漆酶酶促丝素接枝壳聚糖及其膜材料的制备

为改善丝素膜的性能,采用漆酶将壳聚糖接枝到丝素上,制备成具有抗菌性能的复合丝素膜,探讨了壳聚糖质量分数和漆酶对丝素膜结构及其性能的影响。结果显示：酶促丝素接枝壳聚糖的反应溶液中大分子量的蛋白含量增多,证明丝素溶液在发生自交联时还可以接枝壳聚糖;当壳聚糖质量分数为4 g/L时,在酶促丝素接枝壳聚糖后,丝素膜材料在水中的溶失率最小,而溶胀率随着壳聚糖质量分数的增加而增加,且丝素膜材料的表面形貌没有发生明显变化;漆酶催化丝素接枝壳聚糖对丝素蛋白的结晶结构有一定影响;经漆酶催化丝素接枝壳聚糖后,丝素膜的力学性能提升,丝素膜具有了一定的抗菌性能。     

辣根过氧化物酶在纤维材料生物整理中的应用研究进展

针对化学法整理纤维材料存在能耗高、纤维损伤大的缺陷,提出借助酶法在温和条件下对纤维材料进行生物整理加工。介绍了辣根过氧化物酶/双氧水/β-二酮类引发剂乙酰丙酮(HRP/H₂O₂/ACAC)三元催化体系的氧化机制,综述了该体系在淀粉、黄麻和丝蛋白生物改性中的应用,包括:通过酶促反应使丙烯酸甲酯与淀粉接枝共聚,提高淀粉浆料对疏水性纤维的成膜性;通过催化黄麻与丙烯酰胺或甲基丙烯酸六氟丁酯接枝,实现黄麻亲水或疏水化整理;通过酶促反应使丝素与丙烯酸接枝共聚,提升丝素材料的仿生矿化效果;通过催化丝胶与甲基丙烯酸甲酯接枝共聚,改善丝胶基生物材料的成型性。指出HRP在纤维整理及生物材料制备中具有潜在的应用前景。     

高、低相对分子质量再生丝素蛋白改性丝素纤维人工血管材料的探究

采用高、低相对分子质量再生丝素蛋白对He低温等离子体处理的丝素纤维人工血管材料进行表面改性,研究其对丝素纤维人工血管材料生物相容性问题的改善状况.结果显示,接枝再生丝素蛋白可以有效地提升丝素纤维人工血管材料的拉伸断裂强度、初始模量及疏水性.综合考量接枝效果,确定优选质量分数为1％的高相对分子质量再生丝素蛋白溶液和质量分...     

蚕丝丝素的表面结构与活性染料染色性能的关系

应用FTIR(ATR)分析技术和二次微分谱图处理方法研究高温、日晒、蛋白酶处理对丝素微细结构和酪氨酸含量的影响；应用氨基酸分析技术研究上述外界因素对丝素蛋白中具有亲核基团的氨基酸剩基的影响。结果表明：蚕丝纤维经高温、日晒或蛋白酶处理后，活性染料的上染率、固着率、总固着效率有不同程度下降，染色物的表面颜色深度和得色的丰满性也均下降。酪氨酸含量的减少和丝蛋白微细结构的变化是导致活性染料染色性能下降的内在原因。     

马铃薯酪氨酸酶对羊毛的抗菌整理

为了研究生物法对羊毛的改性,文章运用简易方法从马铃薯中提取酪氨酸酶,并以酪氨酸为底物,测试了自制酪氨酸酶的活性,并用它来处理羊毛,以接枝乳铁蛋白,然后利用电镜、红外光谱检测羊毛,并对羊毛进行抗菌整理研究。结果表明,自制的马铃薯酪氨酸酶具有一定活力,通过电镜和红外光谱证明了乳铁蛋白被成功接枝,并具有一定的抗菌性能,对金黄色葡萄球菌的抑菌率达76.32%。     

酶处理后丝素结构变化的拉曼光谱研究

用拉曼光谱研究各种酶对丝素的催化反应，如蛋白质水解酶对柞蚕丝素膜的降解作用、酪氨酸酶对桑蚕丝的氧化反应和壳聚糖对氧化丝素的接枝顺序。 柞蚕丝素膜置入蛋白质水解酶中不同时间后的光谱显示无定形富谷氨酸区的活泼肽链的断裂，使各种氨基酸单元减少。降解没有影响β-折叠链分子构象。 桑蚕丝素经酪氨酸酶氧化后，酪氨酸基团的光谱强度降低，但没有消失。I852／I820强度比值增大表明在强疏水区不易接触到酶的酪氨酸基团。1646cm^-1处亚胺基团的特征谱带证明壳聚糖能高效的接枝到氧化丝素上，可能是经过席夫碱反应。壳聚糖接枝丝素接枝产物的蛋白质组成由β-折叠构象向无规卷曲构象转变。     

紫外光催化法制备丝胶蛋白改性抗静电涤纶织物

涤纶纤维因缺乏亲水性基团易产生静电,文章由此提出借助丝胶蛋白改善涤纶纤维易产生静电的缺陷。研究中以甲基丙烯酸酐乙烯基化改性的丝胶蛋白和涤纶织物为原料,在紫外光辐照下进行基于自由基反应的催化接枝改性,探究了借助丝胶蛋白整理后涤纶纤维中的双键与甲基丙烯酸酐质量浓度关系及接枝改性效果。结果表明：涤纶织物经2.5 g/L十六烷基三甲基溴化铵和1 g/L氢氧化钠质量浓度预处理能促进其表面乙烯化改性,借助红外光谱和碘液着色法验证了涤纶及丝胶中引入了双键,试样强力损失较退浆织物略有降低;经紫外催化丝胶蛋白接枝后,涤纶表面氮元素含量升至2.41%,织物静电半衰期从33.47 s缩减到8.81s,表明抗静电性有明显提升。紫外光催化丝胶蛋白为涤纶织物抗静电整理提供了新方法。     

丝素蛋白溶液对棉织物的改性研究

探讨丝素蛋白溶液对棉织物的改性效果。选用不同浓度的NaOH溶液对棉织物处理后用不同浓度丝素蛋白溶液对织物进行整理。结果表明:织物经碱液处理后纤维表面出现沟槽;失重率有不同程度的增加直至趋于稳定;低浓度的碱液处理有助于织物断裂强力的提高,但织物的强力会随碱液浓度的继续增加而降低;随着丝素蛋白溶液浓度的增加,织物芯吸高度增加,吸湿性提高,但浓度过高会影响织物的吸湿效果;丝素蛋白溶液整理提高了织物的断裂强力和断裂伸长率。认为:不同浓度的丝素蛋白溶液对棉织物改性效果不同,可根据不同要求进行设定。     

丝素蛋白溶液涂层及其在涤纶织物改性中的应用研究

利用蚕丝纤维制备丝素蛋白溶液并对涤纶织物进行涂层处理，然后采用高温乙醇对织物进行后整理以提高丝素涂层牢度。整理后织物表面形态发生改变，呈现出真丝织物的特性。研究结果表明，丝素蛋白溶液涂层处理后织物的厚度基本不变，吸湿性、透气性等服用性能大幅提高，仿真丝效果优良。此外，在丝素蛋白溶液涂层处理过程中添加天竺葵精油，可赋予织物更多的功能。     

Enhancement reactivity of Bombyx mori silk fibroins via genipin-mediated grafting of a tyrosine-rich polypeptide

Bombyx mori silk fibroin has potential applications in the biomedical field owing to its satisfactory biocompatibility. In the present work, a tyrosine-rich polypeptide (P) with the sequence of GKGYGGYGK was grafted onto fibroin molecules using a natural cross-linking agent of genipin (GP), aiming at improving the reactivity of the fibroin-based materials. Incubation of the polypeptide-grafted fibroin membrane was subsequently carried out, with a mushroom tyrosinase (MT) and a model functional macromolecule of ε-poly-l-lysine (ε-PL). The changes in the structure and composition of the silk fibroin before and after polypeptide grafting were examined by means of size exclusion chromatography and amino acid analysis. The results indicated that the polypeptide was covalently bonded to fibroin chains and evidently promoted the succeeding enzymatic coupling of ε-PL with fibroins, resulting in a higher content of ε-PL compared to the control. The obtained antibacterial activities against S. aureus and E. coli for the fibroin membrane treated with GP/P and MT/ε-PL was more satisfactory than others. Cytotoxicity testing reveals that polypeptide grafting did less impact on the biocompatibility of silk fibroins. The present work provides a novel method to improve the reactivity of silk fibroins and it can be utilized for bio-functionalization of silk fibroin.     

蚕丝丝素酪氨酸与活性染料染色性能的关系

对蚕丝织物进行高温、日晒、蛋白酶处理，测定织物处理前后丝素对活性染料上染率、固着率和总固着效率的影响。试验结果表明，蚕丝经处理后对活性染料的染色性能有所下降。通过红外光谱分析和氨基酸组分分析发现，处理后蚕丝表面的酪氨酸含量降低。本文还对丝素氨基酸含量与活性染料染色性能的关系进行了探讨。     

丙三醇缩水甘油醚和壳聚糖对蚕丝织物的复合整理

为了改善蚕丝织物的服用性能,提高其抗皱和抗菌性能,用丙三醇缩水甘油醚和壳聚糖对蚕丝织物进行后整理。采用微波辐照方法接枝丙三醇缩水甘油醚,再用壳聚糖醋酸溶液进行二浸二轧后整理。对整理后的蚕丝织物进行力学性能和白度测试。用正交分析法对整理工艺进行优化,得出最佳处理工艺。结果表明,经整理后,蚕丝织物的抗皱性有较大提高;织物的急弹性回复角提高50°左右,缓弹性回复角提高30°左右,断裂强力和白度略有下降。     

棉织带丝素蛋白丝质化后处理工艺

为进一步提高传统棉织物产品高端化应用,以桑蚕丝下脚料为原料来提取丝素蛋白,并配制成混合水溶液,再以浸轧的方式将其附着在棉织带表面。采用正交试验方法对浸轧工艺参数进行优化设计,并通过扫描电镜(SEM)和能谱仪(EDS)对丝素在棉织带的表面及截面形貌进行分析,考察丝素附着形态。结果表明,最佳浸轧工艺参数为:丝素蛋白溶液质量分数7%,浸轧温度80℃,浸轧压力0.2 MPa。丝素蛋白通过浸轧方式附着于织带表面及部分渗入棉织带内部。     

Studies on photoyellowing of silk fibroin and alteration of its tyrosine content

The photoyellowing progress of silk fibroin and its influence factors under ultraviolet irradiation have been studied, which was conducted by combining different ultraviolet wavelengths, different ultraviolet irradiancies, and different irradiation times. The blue-ray whiteness after ultraviolet irradiation was tested to characterize the course of photoyellowing of silk fibroin. The result shows that the photoyellowing degree of silk fibroin varies significantly under ultraviolet irradiation of different wavelengths and with the increasing in ultraviolet irradiancy at 313-nm wavelength, the photoyellowing degree aggravates correspondingly, while the ultraviolet irradiancy at 340-nm wavelength has little obvious impact. Additionally, the photoyellowing degree of silk fibroin is positively correlated to ultraviolet irradiancy and irradiation time. To quantitatively analyze the alteration of tyrosine content during the photoyellowing of the silk fibroin, l-tyrosine standard curve Y = 8.14666X ? 0.88951 was established using HPLC with linear coefficient r = 0.99991 and precision degree coefficient of tyrosine analyses RSD₁ = 0.21%. Meanwhile, the tyrosine content of silk fibroin after acid hydrolysis was quantitatively analyzed by HPLC with precision degree coefficient RSD₂ = 1.12%. It can be seen that the change rate of the blue-ray whiteness of silk fibroin is positively proportional to the photodegradation rate of tyrosine, but the photodegradation rate of tyrosine ingredient is lower than the change rate of the blue-ray whiteness of silk fibroin.     

不同分子质量丝素蛋白的分离与表征

为获得不同分子质量且分布相对集中的丝素蛋白,采用葡聚糖凝胶层析技术对再生丝素蛋白溶液进行梯度纯化、分离。通过使用合适的葡聚糖凝胶并控制层析流速,有效分离出不同分子质量的丝素蛋白,并进一步对获得的4组不同分子质量的丝素蛋白的黏度、电负性、氨基酸组成和分子构象进行分析。结果表明:丝素蛋白溶液的黏度和等电点随其分子质量的减小而减小,其电负性的提高主要源自于丝素重链被切断,且富含非重复区域的较小分子质量的肽链;4组不同分子质量的丝素蛋白均可自组装形成一定的β-折叠结构,分子质量越高的丝素蛋白越易形成稳定的分子构象。     

Mechanical Properties of Silk Yarn Degummed with Several Proteases

Abstract

The silk filament spun by the silkworm (Bombyx mori) is composed of two fibroin filaments held together by a cementing layer of sericin. Fibroin and sericin account for about 75 wt% and 25 wt% of the raw silk, respectively. The degumming process consists in removing the sericin layer prior to dyeing using a solution of soap, synthetic detergents, or proteolytic enzymes. Silk yarn was degummed with different commercially available enzymes, two alkaline, a neutral, and an acidic proteases and the results were compared in terms of physical and mechanical properties. Proteases were used under optimum conditions of pH and temperature. The treatments were carried out with three different enzyme dosages, that is, 0.2, 1, and 5 U/g yarn. Soap was taken as the standard method of degumming and enzymatic treatments were compared with this method. The degree of polymerization of silk fibroin was assessed by measuring the intrinsic viscosity of the treated samples.     

可溶性丝素蛋白的流变性质和胶凝性质

研究了可溶性丝素蛋白的流变性质和胶凝性质。丝素蛋白溶液的黏度随质量浓度的增加而增加;随着温度的升高,丝素蛋白溶液的黏度不断的降低;在剪切速率为0～30S-1的范围内,丝素蛋白溶液是剪切变稀的假塑性流体,剪切速率大于30S-1时,丝素蛋白溶液是牛顿流体;动态流变性质的研究表明,丝素蛋白溶液是典型的粘性流体;随着丝素蛋白质量浓度的增大,凝胶强度增大;丝素蛋白溶液的质量浓度大于100g/L时,丝素蛋白溶液在加热后的冷却过程中会形成凝胶,丝素蛋白溶液的质量浓度越高,则其胶凝点也越高。     

Effect of silk degumming on the structure and properties of silk fibroin

Two different silk fibroin samples were obtained by the Na₂CO₃ and urea degumming methods of silk fibers in the same fiber dissolution system, respectively. The molecular weight and viscosity of the fibroin samples were analyzed by the methods of SDS-PAGE, rheological, and etc. Then, different silk fibroin membranes (SFMs) and blank microspheres were prepared, and the effects of degumming methods on the silk fibroin were studied via analyzing the differences of SFMs and blank microspheres of the two samples. The experimental results showed that the viscosity of fibroin solution was positively correlated with its molecular weight. The fibroin prepared by the Na₂CO₃ degumming was lower than the one prepared by the urea degumming in the viscosity of the fibroin solution under the same mass concentration. Degumming with Na₂CO₃ exhibited the obvious effects on the thermal stability and mechanical properties of SFM, tensile strength decreased almost 10% and breaking elongation reduced more than 50%. Blank microspheres prepared from silk fibroin degummed with the different methods showed different particle sizes and its distribution. The microspheres prepared from silk fibroin degummed with the Na₂CO₃ had the smaller particle sizes and more concentrated distribution compared with those with the urea.