酶分子修饰和改造

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（从从N N端端失失去去4 44 4个个氨氨基基酸酸残残基基）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对二硫键的对二硫键的3容许扭容许扭转角分布图转角分布图706对已知二硫键的能量值分布图对已知二硫键的能量值分布图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. 酶修饰剂天然酶修饰酶/时间/时间残留酶活%残留酶活%-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 细菌细菌诱发突变的诱发突变的因素因素5050 0 0C C培养培养突变体库突变体库选择压力选择压力（温度）（温度）温度耐受型突温度耐受型突变体变体最适生长温度为最适生长温度为37370 0C C最适生长温度提高了！最适生长温度提高了！DNA shuffling体体外外定定向向进进化化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