毕赤酵母表达重组植酸酶酶学性质的比较研究

Comparative studies on the enzymology properties of severval phytases expressed by Pichia pastoris

通过酶学性质比较毕赤酵母GS115表达的E.coli K12植酸酶（appA）及其突变体植酸酶（appANR）和黑曲霉植酸酶（phyA）的最适pH、温度、热稳定性及对胃蛋白酶和胰蛋白酶的耐受性.结果表明,在95℃,加热10 min,appA NR可残余90%左右的活力,而其他两种只残余20%~50%的活力;appA NR和phyA具有两个最适pH值,而appA只有一个;相对phyA,appA及其突变体appA NR都具有良好的胃蛋白酶和胰蛋白酶耐受性.因此appA NR无论是热稳定性还是pH耐受性及对胃、胰蛋白酶的耐受性都比野生型appA和phyA更具备工业饲料要求的酶学特性.

The enzymology properties of three crude recombinate phytase preparations were compared.The encoding genes of the enzyme were E.coli K12 appA wild type,appA mutation appA NR,and Aspergillus niger phyA,and heterogenous expressed in Pichia pastoris.The enzymes were studied for their pH behaviour,temperature optimum,thermostability and resistance to protease inactivation and found to exhibit different properties depending on source of the phytase gene.The results showed that appA NR were more thermostable,pH tolerance,and trypsinase and pepsin resistant than compared to other enzymes.So,appA NR with properties of high temperature stability,broad pH range and high proteolytic stability is favourable for future applications as feed additives.