Greene P J, Yu P L, Zhao J, Schiffer C A, Santi D
Department of Biochemistry, University of California, San Francisco 94143.
Protein Sci. 1994 Jul;3(7):1114-6. doi: 10.1002/pro.5560030715.
The thymidylate synthase (TS) gene from Lactococcus lactis has been highly expressed in Escherichia coli. The TS protein was purified by sequential chromatography on Q-Sepharose and phenyl-Sepharose. Six grams of cell pellet yielded 140 mg of homogeneous TS. TS is a highly conserved enzyme, and several of the conserved amino acid residues that have been implicated in catalytic function are altered in L. lactis TS. By use of a 3-dimensional homology model, we have predicted covariant changes that might compensate for these differences. With the large amounts of L. lactis TS now available, studies can be pursued to understand the structure-function relationships of this enzyme compared to other TSs and to confirm the presumed roles of the compensatory changes predicted in the homology model.
乳酸乳球菌的胸苷酸合成酶（TS）基因已在大肠杆菌中得到高效表达。TS蛋白通过先后在Q-琼脂糖和苯基琼脂糖上进行层析纯化。6克细胞沉淀可产生140毫克纯的TS。TS是一种高度保守的酶，在催化功能中涉及的几个保守氨基酸残基在乳酸乳球菌TS中发生了改变。通过使用三维同源性模型，我们预测了可能补偿这些差异的协变变化。由于现在有大量的乳酸乳球菌TS可用，因此可以开展研究以了解该酶与其他TS相比的结构-功能关系，并确认同源性模型中预测的补偿性变化的假定作用。
