Harms E, Wehner A, Aung H P, Röhm K H
Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907.
FEBS Lett. 1991 Jul 8;285(1):55-8. doi: 10.1016/0014-5793(91)80723-g.
A threonine-12 to alanine mutant of E. coli asparaginase II (EC 3.5.1.1) has less than 0.01% of the activity of wild-type enzyme. Both tertiary and quaternary structure of the enzyme are essentially unaffected by the mutation; thus the activity loss seems to be the result of a direct impairment of catalytic function. As aspartate is still bound by the mutant enzyme, Thr-12 appears not be involved in substrate binding.
大肠杆菌天冬酰胺酶II（EC 3.5.1.1）的苏氨酸-12突变为丙氨酸的突变体，其活性不到野生型酶的0.01%。该酶的三级和四级结构基本上不受突变影响；因此，活性丧失似乎是催化功能直接受损的结果。由于天冬氨酸仍与突变酶结合，苏氨酸-12似乎不参与底物结合。
