蔗糖酶的固定化及其条件的优化

通过比较各种固定方法确定固定化蔗糖酶的最佳载体,并优化反应条件,确定明胶包埋法为固定化蔗糖酶的适宜载体,并结合交联法,采用戊二醛为交联剂.按此法制备的固定化蔗糖酶在较高pH及较高温度下都保持活力,且其储存稳定性及操作稳定性比游离酶都有显著的提高.

Abstract：

The methods of immobilized sucrase and the optimized conditions were studied in this paper. The results indicated that the best sorbent is the glutin with glutaraldehyde as crosslinking agent. The optimal conditions for immobilization of sucrase were: ratio of 20% glutin to sucrase 2 : 1, 2% CaCl2 solution for 1 hour, 5 % glutaraldehyde for 1 hour. The optimal pH and temperature for immobilized enzyme were 5.0 and 55 ℃. the reserve stability and reusing stability have prominent improved after immobilization.     

青鱼胰蛋白酶的分离纯化及部分性质研究

[目的]为青鱼的养殖和综合利用提供试验依据。[方法]对青鱼胰蛋白酶进行分离纯化,测定青鱼胰蛋白酶的分子量、热稳定性和酸碱稳定性,探讨pH值、温度、金属离子和EDTA对青鱼胰蛋白酶活力的影响。[结果]经SDS-PAGE和凝胶过滤,测得青鱼胰蛋白酶的分子量分别为44和43.5 kD。青鱼胰蛋白酶具有一定碱性耐受性,在pH值为8～10时活性较高,其最适pH值约为9,最适反应温度为50℃。以酪蛋白为底物,在pH值8.5、37℃时测得该酶Km值为4.6×103 mg/L。Mg2+对该酶有明显促进作用,而Cu2+、Mn2+、Pb2+和EDTA对青鱼胰蛋白酶的抑制作用很大。[结论]EDTA能抑制青鱼胰蛋白酶的作用,说明该酶可能为金属蛋白酶。     

柳树叶的原花青素的抗氧化性研究

用化学比色法分别测定柳树叶原花青素的总抗氧化力、还原力、对O2-·,·OH,H2O2和屡NO2-的清除作用,并与发Vc相比较,结果表明,在这一系列抗氧试验中,原花青素的抗氧化性均较Vc强,要相同浓度下,二者对O2-·和H2O2的清除作用相差不大,在总抗氧化力和还原力测定和对NO2-清除作用约为Vc的2倍,在对·OH的清除上,原花青素浓度为3 μg/mL时,清除率达8.9%,而Vc浓度为4.8 mg/mL时清除率为10.5%.

Abstract：

The total antioxidative activity and reductive activity of procyanidins(PC) from the leaves of willow and their scavenging of the free radicals O2- · , · OH, H2 O2 and NO2- were studied by spectrophotometry, and the results were compared with the effects of vitamin C (Vc). Procyanidins were shown to have stronger antioxidative activity than Vc, and PC and Vc were not significantly different in their scavenging rate for O2- · and H2O2. The total antioxidative activity, reductive activity and scavenging of NO2- of PC were approximately twice those of Vc. The scavenging rate of PC for · OH was 8. 9% with a PC concentration of 3 μg/mL and that of Vc for · OH was 10.5 % with a Vc concentration of 4.8 mg/mL.