Aĭvazashvili V A, Mikhaĭlov S N, Padiukova N Sh, Bibilashvili R Sh, Karpeĭskiĭ M Ia
Mol Biol (Mosk). 1987 Jul-Aug;21(4):1080-91.
It was shown that RNA-polymerase is able to discriminate diastereoisomers of 5'-methyl-substituted analogs of ribonucleoside triphosphates (rNTP). Under conditions of soil substrate reactions when the analog is added to the presynthesized ternary complexes, D-allo- and L-talo-stereoisomers incorporate into RNA 100 and 1000 times, respectively, less effectively, then the natural rNTP. The effectivities of incorporation of other 2'- and 3'-substituted analogs of rNTP were measured under the same conditions and compared with that for 5'-Me-rNTP. It was shown also that RNA-polymerase does not support long-chain RNA synthesis from 5'-Me-rNTP in the absence of natural rNTP. No more then two analog residues can be attached to the 3'-end of the presynthesized RNA under such conditions. Addition of one natural rNTP to this reaction mixture results in the synthesis of long alternating RNA containing D-allo-stereoisomer and natural rNTP residues. In the case of L-talo-stereoisomer RNA elongation is not inhibited, if the distance between the analog residues in the RNA chain is not shorter then five nucleotide residues. The rate of pyrophosphorolysis from the RNA of the analogs studied was the same as for the natural rNTP residues.
结果表明，RNA聚合酶能够区分核糖核苷三磷酸（rNTP）的5'-甲基取代类似物的非对映异构体。在土壤底物反应条件下，当将类似物添加到预先合成的三元复合物中时，D-别-和L-塔罗-立体异构体分别以低100倍和1000倍的效率掺入RNA，低于天然rNTP。在相同条件下测量了rNTP的其他2'-和3'-取代类似物的掺入效率，并与5'-Me-rNTP的掺入效率进行了比较。还表明，在没有天然rNTP的情况下，RNA聚合酶不支持由5'-Me-rNTP进行长链RNA合成。在这种条件下，预先合成的RNA的3'-末端连接的类似物残基不超过两个。向该反应混合物中加入一种天然rNTP会导致合成包含D-别-立体异构体和天然rNTP残基的长交替RNA。对于L-塔罗-立体异构体，如果RNA链中类似物残基之间的距离不短于五个核苷酸残基，则RNA延伸不会受到抑制。所研究的类似物从RNA上的焦磷酸解速率与天然rNTP残基相同。
