【作者】 董绍伟；

【导师】 陆大年；

【作者基本信息】 东华大学 ， 纺织化学与染整工程， 2009， 博士

【摘要】 生物酶的高效性、专一性和环境友好等特性使其受到人们的关注,应用也越来越广泛。但由于大多数酶是蛋白质,在高温时不可避免发生失活行为,生物酶的热稳定性差已经成为限制其高温应用的重要瓶颈,因此研究生物酶的热稳定性及探索提高酶耐热性的方法具有极为重要的意义。本论文首先研究了α-淀粉酶在溶液中的热稳定性,探讨了各种添加剂对α-淀粉酶耐热性的影响,并研究了酶在失活前后的粒径和荧光变化情况,分析了引起α-淀粉酶热失活的原因。结果表明,中温α-淀粉酶在溶液中的热失活符合一级动力学,其热稳定性很差,醋酸钙、乳酸钠、L-组氨酸和低分子量壳聚糖(LWCS)能够明显提高α-淀粉酶的耐热性。其中,LWCS的效果最好。醋酸钙和乳酸钠的复合物对α-淀粉酶A的热稳定性具有促进作用,这种作用效果比单独使用两种添加剂要好得多,但对α-淀粉酶B却没有这种效果。α-淀粉酶在高温下,粒径增大,发生聚集,而热稳定剂能通过抑制酶的聚集延缓酶的失活。而荧光光谱分析表明,热稳定剂的加入也改变了酶的构象,使其处于更完美的状态,从而提高了酶的耐热性。在退浆时,酶的失活行为发生在织物上,本论文也研究了α-淀粉酶在棉织物上的热稳定性。结果表明,中温α-淀粉酶在棉织物上的热失活同样符合一级动力学,但失活速率相对其在溶液中明显变慢,这说明棉织物也是α-淀粉酶很好的热稳定剂。加入各种添加剂后,酶的耐热性进一步得到改善,尤其是LWCS的加入,能够使α-淀粉酶在100℃以上保持较好的热稳定性。在此基础上,通过单因素和正交实验,确定了各种因素对棉织物α-淀粉酶退浆效果的影响,得到了最佳的处理工艺为:α-淀粉酶B浓度为0.5 g/L,LWCS浓度为15 mmol/L,汽蒸时间为15 min,汽蒸温度为100℃,溶液pH值为6,在此工艺条件下对棉织物进行退浆处理后,测定退浆率为98.6%。果胶酶在纺织上,尤其是在棉织物精练中的应用,越来越广泛,但果胶酶的性能研究却不够深入。本论文详细探索了精练用果胶酶酶活的测定方法,结果发现,果胶酶A由于能够水解苹果果胶,而且产物在紫外区236 nm处出现特征吸收峰,所以可以采用紫外法测定其活性。但果胶酶A无法作用于棉织物上的果胶,所以不能用于棉织物精练;果胶酶B由于无法水解苹果果胶,不能采用紫外法测定其活性,但果胶酶B能水解棉织物上的果胶,因此可以以棉织物上的果胶为底物,通过研究果胶酶B对果胶的去除情况,测定其酶活。本论文也研究了果胶酶B的酶学性质和热稳定性,当果胶酶B的浓度为0.16 g/L时,果胶酶B的最适温度为70℃,最适pH值范围为7～9。果胶酶B在低于70℃具有较好的热稳定性,在70℃时失活半衰期为131.2 min。棉织物上的果胶和蜡质都会影响其润湿性能,而且蜡质的影响效果要远远大于果胶物质。因此,在精练时需要结合果胶酶和表面活性剂的作用,同时去除果胶和蜡质。通过单因素实验和正交分析,确定果胶酶棉织物精练的最佳工艺为:预处理(沸水煮5 min)→处理液(果胶酶B溶液2 g/L,pH=7)→两浸两轧(轧液率100%)→90℃处理30 min→2 g/L平平加O溶液中100℃煮20 min→充分水洗。处理后,果胶去除率为93.8%,毛效为18.4 cm。本论文采用一浴法对棉织物进行退浆、精练,确定最佳的处理工艺为:处理液(α-淀粉酶0.5 g/L,果胶酶B 1g/L)→两浸两轧(轧液率100%)→90℃处理20 min→2 g/L平平加O溶液中100℃处理20 min→充分水洗。在此工艺条件下测得织物的前处理效果为:退浆率96.4%,果胶去除率90.4%,毛效18.6 cm。更多还原

【Abstract】 The enzymes have got more attention and applications for their efficiency, specificity and mild action conditions. However, because most enzymes are proteins, inactivation behavior will take place inevitably at high temperatures. Poor thermostability has become the limitation of applications of enzymes at high temperatures. Therefore, it is very important to study the enzymatic thermostability and explore the methods of improving the thermal resistance of enzymes.Firstly, the thermostability ofα-amylase in solution was studied. The influence of several additives on the thermostability ofα-amylase was discussed. The varieties of particle sizes and fluorescence spectrum in the inactivation process were investigated. The results showed that inactivation of mesophilicα-amylases in solution followed first order kinetics. Calcium acetate, sodium lactate, L-histidine and low molecular weight chitosan (LWCS) could improve the thermostability of the enzymes remarkably. Among these additives, LWCS had best stabilizing effect. The composite of calcium acetate and sodium lactate had positive action on the thermostability ofα-amylase A, which was better than that when the additives was used individually. But the composite did not have such effect on the thermostability ofα-amylase B.α-Amylase aggregated and the particle size was increased at high temperatures. The thermal stabilizers postponed the inactivation through restrained the aggregation of the enzyme. The results from fluorescence spectroscopy measurements showed that the addition of stabilizers changed the conformation of the enzyme and made the enzyme in more ideal status, which was favorable to the thermostability of the enzyme.The inactivation of enzymes occurred on the fabrics in desizing process. The thermostability ofα-amylase on the fabrics was studied. The results showed that the inactivation of the enzyme on the fabrics also followed first order kinetics. But the inactivation rate ofα-amylase on the fabric was much slower than that in solution, which demonstrated that the fabrics were also good thermal stabilizers of the enzyme. After several stabilizers were added, the thermostability was further improved. Especially the addition of LWCS could make theα-amylase obtain preferable thermostability at temperatures higher than 100℃.Influences of various factors on the desizing effect of cotton fabrics were studied by "change-one-factor-at-a-time" method and orthogonal design. The optimal process conditions were set as follows: steaming temperature 100℃, steaming time 15 min,α-amylase B concentration 0.5 g/L, pH=6, LWCS concentration 15 mmol/L. The cotton was desized under this condition and the desizing ratio was 98.6%.The pectinase has obtained more and more application on the scouring of cotton fabric. But the study of the enzyme property is not intensive enough. In this paper, the activity of pectinase for scouring was explored in detail. It could be observed that pectinase A could hydrolyze apple pectin and the product had a characteristic absorption peak at 236 nm in ultraviolet region. Therefore, ultraviolet spectrophotometry method could be used to measure the activity of pectinase A. However, pectinase A had no effect on the pectin in cotton fabrics and this enzyme was not suitable for the souring of cotton fabrics. Pectinase B could not hydrolyze apple pectin and ultraviolet spectrophotometry method could not be applied to measuring its activity. But because pectinase B was able to hydrolyze the pectin in cotton fabrics, its activity could be characterized via the removing ability of pectin of cotton fabrics.The enzymology property and thermostability of pectinase B was investigated. When the concentration of pectinase B was 0.16 g/L, the optimal temperature was 70℃, the optimal pH value was 7-9. Pectinase B had good thermostability at temperatures lower than 70℃, and the half life time at 70℃was 131.2 min.Both the pectin and wax in cotton fabrics had effects on the wettability. And the effect of wax was much deeper than that of the pectin. Therefore, the pectinase and surfactant should be combined to remove pectin and wax at the same time in scouring process. Through "change-one-factor-at-a-time" method and orthogonal design, the optimal souring process conditions were determined as follows: pretreatment (5 min)→2 dip-squeeze (pectinase B 2 g/L, pH=7)→treatming for 30min at 90℃→treating for 20 min in 2 g/L paregal O solution at 100℃→washing thoroughly. After the treatment, the removing ratio of pectin was 93.8%, the capillary effect was 18.4 cm.Lastly, the cotton fabrics were treated by one-bath desizing-scouring method withα-amylase and pectinase and the conditions were optimized and adjusted, which was as follows. Solution (α-amylase B 0.5g/L, pectinase B 1g/L)→2 dip-squeeze (Liquid pickup 100%)→treatming for 20min at 90℃→treating for 20 min in 2 g/L paregal O solution at 100℃→washing thoroughly. Under this condition, the desizing ratio was 96.4%, the removing ratio was 90.4%, and the capillary effect was 18.6 cm.更多还原