Pratt E A, Ho C
Biochemistry. 1975 Jul;14(13):3035-40. doi: 10.1021/bi00684a037.
A tryptophan-requiring strain of Escherichia coli can go through two doublings of optical density after L-tryptophan is replaced in the medium by 4-fluorotryptophan, during which the fluoro analog displaces approximately 75% of the L-tryptophan in cell protein. One doubling occurs in the presence of 5- or 6-fluorotryptophan, with 50-60% replacement of L-tryptophan by analog. When beta-galactosidase is induced at the time of addition of analog, it reaches 60% of the control specific activity in the presence of 4-fluorotryptophan, 10% of normal in the presence of 5- or 6-fluorotryptophan. Lactose permease activity is 35% of the control in the presence of 4- and 6-fluorotryptophan, less than 10% in the presence of 5-fluorotryptophan. D-Lactate dehydrogenase shows a specific activity twice that of the control in the presence of 4-fluorotryptophan, one-half with 5- or 6-fluorotryptophan. Thus fluorotryptophan can be incorporated into proteins and affect their activities, although the nature and magnitude of the effect cannot be predicted for any given enzyme. Such substituted proteins should be useful for the study of protein structure and function by 19F nuclear magnetic resonance and other techniques.
一种对色氨酸有需求的大肠杆菌菌株，在培养基中的L-色氨酸被4-氟色氨酸取代后，其光密度可经历两次翻倍，在此期间，这种氟代类似物在细胞蛋白质中取代了约75%的L-色氨酸。在5-或6-氟色氨酸存在的情况下会发生一次翻倍，其中类似物取代了50-60%的L-色氨酸。当在添加类似物时诱导β-半乳糖苷酶，在4-氟色氨酸存在的情况下，它达到对照比活性的60%，在5-或6-氟色氨酸存在的情况下为正常的10%。在4-和6-氟色氨酸存在的情况下，乳糖通透酶活性为对照的35%，在5-氟色氨酸存在的情况下小于10%。D-乳酸脱氢酶在4-氟色氨酸存在的情况下比活性是对照的两倍，在5-或6-氟色氨酸存在的情况下为对照的二分之一。因此，氟色氨酸可以掺入蛋白质并影响其活性，尽管对于任何给定的酶，其影响的性质和程度无法预测。这种被取代的蛋白质对于通过19F核磁共振和其他技术研究蛋白质结构和功能应该是有用的。
