一种耐热性植酸酶的分离纯化及其酶学性质研究

采用半固态发酵方式培养泡盛曲霉(Aspergillus awamori)AS3.324,通过有机膜超滤、阴离子交换层析、凝胶层析后,得到纯化的植酸酶。酶学性质表明,其反应最适温度为50-55℃,最适pH为5.5,在37℃下以植酸钠为底物的Km值为1.03 nmol/L,Vmax为2.13μmol/(L.min)。EDTA基本不影响植酸酶活性;Ca2+,Mg2+,Mn2+对植酸酶活性有轻微的抑制作用;Fe2+,Zn2+对酶促反应有显著的抑制作用。对该酶的耐热性研究表明,经较高温度条件处理后,仍有较高残余酶活性,与当今商品化的植酸酶相比,有较强的耐热性。泡盛曲霉植酸酶作为动物饲料添加剂具有广泛的应用前景。

Purification and Characterization of Thermostable Phytase from Aspergillus awamori

Extracellular phytase produced by Aspergillus awamori 3.324 using technique of semi-solid cultivation was purified to homogeneity by employing an initial ultrafiltration step,followed by chromatography using ion exchange,gel filtration and chromatofocusing steps.The purified enzyme was a 118 ku protein including 31% glycosylation.It possessed a temperature optimum of 50～55℃,and pH optimum of 5.5.The Km values of the phytase for dodecasodium phytate at 37℃ was 1.03 nmol/L with a Vmax 2.13 μmol/(L·min).Phytase activity was not significantly affected by EDTA.Activity was moderately inhibited by Ca(2+),Mg(2+),Mn(2+) and was evidently inhibited by Fe(2+),Zn(2+).The enzyme displayed higher thermostability at the high temperature than the commercial phytase product.Initial characterization of the purified enzyme suggested that it could be a potential candidate for use as an animal feed supplement.