酶分子修飾和改造

1、a a、胃蛋白酶原的激活、胃蛋白酶原的激活 HCl胃胃蛋蛋白白酶酶原原pH1.52（從從N N端端失失去去4 44 4個(gè)個(gè)氨氨基基酸酸殘殘基基）自自身身激激活活胃胃蛋蛋白白酶酶b b、胰蛋白酶原（、胰蛋白酶原（trypsinogentrypsinogen）的激活）的激活 c c、胰凝乳蛋白酶原（、胰凝乳蛋白酶原（chymotrypsinogenchymotrypsinogen）的激活）的激活 Sequence ASequence ASequence BSequence BSequence CSequence CSequence DSequence DNCBI-blast analysis of

2、 XynBThe analysis result of suitable point of introducing disulfide bridge of XynB351對(duì)二硫鍵的對(duì)二硫鍵的3容許扭容許扭轉(zhuǎn)角分布圖轉(zhuǎn)角分布圖706對(duì)已知二硫鍵的能量值分布圖對(duì)已知二硫鍵的能量值分布圖PropertiesWild typeMutant CX8Topt ()4550t1/2 (min)10180Specific activity (U/mg)2127.983.93330.9173.4Km (mg/ml)56.937.2Vmax (mmol/ml.min.mg)82.927.0 Properties

3、of the wild type and mutant xylanase Xingzhou Chen et al. Site-directed mutagenesis of an Aspergillus niger xylanase B and its expression, purification and enzymatic characterization in Pichia pastoris. Process Biochemistry. 2010. 45: 75-80. 酶修飾劑天然酶修飾酶/時(shí)間/時(shí)間殘留酶活%殘留酶活%-淀粉酶 右旋糖苷 37 / 100 min 70 37 / 1

4、00 min 70 -淀粉酶 右旋糖苷 60 / 5 min 50 60 / 175 min 50 細(xì)菌細(xì)菌誘發(fā)突變的誘發(fā)突變的因素因素5050 0 0C C培養(yǎng)培養(yǎng)突變體庫突變體庫選擇壓力選擇壓力（溫度）（溫度）溫度耐受型突溫度耐受型突變體變體最適生長溫度為最適生長溫度為37370 0C C最適生長溫度提高了！最適生長溫度提高了！DNA shuffling體體外外定定向向進(jìn)進(jìn)化化Increasing the ee-value of the lipase-Increasing the ee-value of the lipase-catalyed hydrolysis of the chiral estercatalyed hydrolysis of the chiral ester2%2%31%31%57%57%75%75%81%81%0%0%0 01 12 23 34 4mutant generationsmutant generations%ee%ee