Tsavdaridis I K, Triantafillidou D C, Kyriakidis D A
Laboratory of Biochemistry, Faculty of Chemistry, Aristotelian University of Thessaloniki, Greece.
Biochem Mol Biol Int. 1994 Jan;32(1):67-77.
In T. thermophila two forms of L-asparaginase (EC 3.5.1.1) were extracted and purified to near homogeneity which are associated with membranes. These two forms of L-asparaginase, I or II, act optimally at pH 8.6 and do not present any glutaminase or kinase activity. Both activities reach maximal values at the stationary phase of growth of T. thermophila. L-Asparaginases are solubilized by treatment of the particulates with 2% w/v Triton X-100 and then by sodium phosphate buffer pH 8.0. Both forms cross reacted with antibodies raised against T. pyriformis L-asparaginase and show isoelectric points 7.4 and 8.2. Among the metals tested, Ca2+ is the most effective in activating L-asparaginase I or II activity. Sorbitol alone up to 30% w/v in the assay mixture activates more than 10 x fold the activity of L-asparaginase II. Incubation of L-asparaginase I or II with increasing concentration of phospholipase C results in gradually loss of their activities. The relative effectiveness of a variety of phospholipids to reconstitute enzyme activity is presented as well.
在嗜热栖热菌中，两种与膜相关的L-天冬酰胺酶（EC 3.5.1.1）被提取并纯化至接近均一状态。这两种形式的L-天冬酰胺酶，即I型或II型，在pH 8.6时活性最佳，且不具有任何谷氨酰胺酶或激酶活性。两种活性在嗜热栖热菌生长的稳定期达到最大值。通过用2% w/v Triton X-100处理颗粒，然后用pH 8.0的磷酸钠缓冲液处理，可使L-天冬酰胺酶溶解。两种形式均与针对梨形四膜虫L-天冬酰胺酶产生的抗体发生交叉反应，其等电点分别为7.4和8.2。在所测试的金属中，Ca2+对激活L-天冬酰胺酶I或II的活性最为有效。在测定混合物中，单独高达30% w/v的山梨醇可使L-天冬酰胺酶II的活性激活超过10倍。将L-天冬酰胺酶I或II与浓度不断增加的磷脂酶C一起孵育，会导致其活性逐渐丧失。还展示了多种磷脂对恢复酶活性的相对有效性。
