Freist W, Sternbach H, von der Haar F, Cramer F
Eur J Biochem. 1978 Mar 15;84(2):499-502. doi: 10.1111/j.1432-1033.1978.tb12192.x.
Sixteen analogues of ATP have been tested in the aminoacylation reaction of threonyl-tRNA, lysyl-tRNA, and arginyl-tRNA synthetases from baker's yeast. Two compounds are substrates for threonyl-tRNA and for lysyl-tRNA synthetases and five compounds for arginyl-tRNA synthetase. There are six inhibitors for threonyl-tRNA, nine for lysyl-tRNA, and six for arginyl-tRNA synthetase. Their Km and Ki values have been determined. Thus positions 2, 6, 7, 8 and 9 of the purine moiety and 2' and 3' of the sugar moiety of the ATP molecule are important for catalytic action of these aminoacyl-tRNA synthetases. Remarkably arginyl-tRNA synthetase is the first aminoacyl-tRNA synthetase which tolerates bulky substituents at the sugar moiety of ATP. These data fit with the idea that synthetases of subunit structure need magnesium-ion-ATP complexes with an anti conformation as substrates whereas single-chain enzymes accept this substrate in the syn conformation.
已对16种ATP类似物在面包酵母的苏氨酰 - tRNA、赖氨酰 - tRNA和精氨酰 - tRNA合成酶的氨酰化反应中进行了测试。有两种化合物是苏氨酰 - tRNA和赖氨酰 - tRNA合成酶的底物，有五种化合物是精氨酰 - tRNA合成酶的底物。有六种是苏氨酰 - tRNA合成酶的抑制剂，九种是赖氨酰 - tRNA合成酶的抑制剂，六种是精氨酰 - tRNA合成酶的抑制剂。已经测定了它们的Km和Ki值。因此，ATP分子嘌呤部分的第2、6、7、8和9位以及糖部分的2'和3'位对于这些氨酰 - tRNA合成酶的催化作用很重要。值得注意的是，精氨酰 - tRNA合成酶是第一个能耐受ATP糖部分存在大体积取代基的氨酰 - tRNA合成酶。这些数据符合这样的观点，即亚基结构的合成酶需要反式构象的镁离子 - ATP复合物作为底物，而单链酶则接受顺式构象的这种底物。
