Wolska-Mitaszko Barbara, Jaroszuk-Sciseł Jolanta, Pszeniczna Katarzyna
Department of Molecular Biology, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland.
Mycol Res. 2007 Apr;111(Pt 4):456-65. doi: 10.1016/j.mycres.2007.01.018. Epub 2007 Feb 21.
Enzymatic assays and native PAGE were used to study trehalase and invertase activities, depending on culture age and different sugar conditions, in cell-free extracts, culture filtrates and ribosomal wash of Fusarium oxysporum. The activity of invertase preceded that of trehalase; in the exponential phase of growth, mainly invertase activity was produced, whereas trehalase activity was high in the stationary phase. In this last phase of growth, the activity of intracellular trehalase was repressed by monosaccharides, whereas disaccharides, especially lactose and starch, enhanced the activity of intracellular and extracellular trehalase. However, invertase activity was not repressed under these conditions and had the maximal activity in the presence of saccharose. Intracellular trehalase appeared in a single, high-molecular weight (120 kDa) form, whereas the extracellular enzyme appeared in a single, low-molecular weight (60 kDa) form. The activity pattern of invertase isoforms indicated the occurrence of three forms of intracellular enzyme with the main activity band at 120 kDa and two isoforms of extracellular enzyme. In the ribosomal wash, high-molecular weight isoforms of both trehalase and invertase were identified. A possible role of trehalase and invertase in carbohydrate metabolism of fungal pathogens is also discussed.
采用酶活性测定和非变性聚丙烯酰胺凝胶电泳（native PAGE），研究了尖孢镰刀菌无细胞提取物、培养滤液和核糖体洗脱液中，海藻糖酶和转化酶活性随培养时间及不同糖类条件的变化情况。转化酶的活性先于海藻糖酶；在生长指数期，主要产生转化酶活性，而在稳定期海藻糖酶活性较高。在生长的最后阶段，单糖可抑制细胞内海藻糖酶的活性，而双糖，尤其是乳糖和淀粉，则可增强细胞内和细胞外海藻糖酶的活性。然而，在这些条件下转化酶活性并未受到抑制，且在蔗糖存在时活性最高。细胞内海藻糖酶以单一的高分子量（120 kDa）形式出现，而细胞外酶则以单一的低分子量（60 kDa）形式出现。转化酶同工酶的活性模式表明，细胞内酶存在三种形式，主要活性带位于120 kDa，细胞外酶存在两种同工酶。在核糖体洗脱液中，鉴定出了海藻糖酶和转化酶的高分子量同工酶。还讨论了海藻糖酶和转化酶在真菌病原体碳水化合物代谢中的可能作用。
