Freist W, Cramer F
Eur J Biochem. 1980;107(1):47-50. doi: 10.1111/j.1432-1033.1980.tb04622.x.
The analogs of ATP have been tested in the ATP/PPi exchange reaction of phenylalanyl-tRNA, lysyl-tRNA, isoleucyl-tRNA and arginyl-tRNA synthetases from baker's yeast. Three compounds are substrates for phenylalanyl-tRNA, seven for lysyl-tRNA, two for isoleucyl-tRNA and five for arginyl-tRNA synthetase. Their Km and V values have been determined. No analog was an inhibitor. (3'-dATP), 3'-Deoxyadenosine 5'-triphosphate which is an inhibitor of the four enzymes in the aminoacylation reaction, becomes a good substrate in the PPi exchange. Additionally lysyl-tRNA synthetase accepts two analogs with modifications at position 6 of the purine and three analogs modified at the ribose moiety as substrates in the PPi exchange, whereas these compounds are inactive or inhibitors in the aminoacylation reaction. In general the enzymes are less specific in the ATP/PPi exchange and the results indicate a more sophisticated proof of the nucleotide moiety upon aminoacylation. This could occur with the aminoacyladenylate intermediate as well as with any other intermediate.
已在来自面包酵母的苯丙氨酰 - tRNA、赖氨酰 - tRNA、异亮氨酰 - tRNA和精氨酰 - tRNA合成酶的ATP/焦磷酸交换反应中测试了ATP的类似物。三种化合物是苯丙氨酰 - tRNA合成酶的底物，七种是赖氨酰 - tRNA合成酶的底物，两种是异亮氨酰 - tRNA合成酶的底物，五种是精氨酰 - tRNA合成酶的底物。已测定了它们的Km和V值。没有类似物是抑制剂。（3'-dATP），即3'-脱氧腺苷5'-三磷酸，它在氨酰化反应中是这四种酶的抑制剂，但在焦磷酸交换反应中成为良好的底物。此外，赖氨酰 - tRNA合成酶在焦磷酸交换反应中接受嘌呤第6位有修饰的两种类似物和核糖部分有修饰的三种类似物作为底物，而这些化合物在氨酰化反应中无活性或为抑制剂。一般来说，这些酶在ATP/焦磷酸交换反应中的特异性较低，结果表明在氨酰化过程中对核苷酸部分的验证更为复杂。这可能发生在氨酰腺苷酸中间体以及任何其他中间体上。
