Brugger R, Simões Nunes C, Hug D, Vogel K, Guggenbuhl P, Mascarello F, Augem S, Wyss M, van Loon A P G M, Pasamontes L
Biotechnology Department, Roche Vitamins Ltd, Building 203/17B, 4070 Basel, Switzerland.
Appl Microbiol Biotechnol. 2004 Jan;63(4):383-9. doi: 10.1007/s00253-003-1337-0. Epub 2003 Jun 12.
Aspergillus fumigatus phytase has previously been identified as a phytase with a series of favourable properties that may be relevant in animal and human nutrition, both for maximising phytic acid degradation and for increasing mineral and amino acid availability. To study the natural variability in amino acid sequence and its impact on the catalytic properties of the enzyme, we cloned and overexpressed the phytase genes and proteins from six new purported A. fumigatus isolates. Five of these phytases displayed < or= 2 amino acid substitutions and had virtually identical stability and catalytic properties when compared with the previously described A. fumigatus ATCC 13073 phytase. In contrast, the phytase from isolate ATCC 32239 ( Sartorya fumigata, the anamorph of which was identified as A. fumigatus) was more divergent (only 86% amino acid sequence identity), had a higher specific activity with phytic acid, and displayed distinct differences in substrate specificity and pH-activity profile. Finally, comparative experiments confirmed the favourable stability and catalytic properties of A. fumigatus phytase.
烟曲霉植酸酶先前已被鉴定为一种具有一系列有利特性的植酸酶，这些特性在动物和人类营养中可能具有相关性，既有利于最大限度地降解植酸，也有利于提高矿物质和氨基酸的利用率。为了研究氨基酸序列的自然变异性及其对酶催化特性的影响，我们克隆并过表达了来自六个新的所谓烟曲霉分离株的植酸酶基因和蛋白质。其中五种植酸酶显示出≤2个氨基酸替换，与先前描述的烟曲霉ATCC 13073植酸酶相比，其稳定性和催化特性几乎相同。相比之下，来自分离株ATCC 32239（烟曲霉变种，其无性型被鉴定为烟曲霉）的植酸酶差异更大（氨基酸序列同一性仅为86%），对植酸具有更高的比活性，并且在底物特异性和pH活性曲线方面表现出明显差异。最后，比较实验证实了烟曲霉植酸酶具有良好的稳定性和催化特性。
