Ferris James P
Department of Chemistry, Rensselaer Polytechnic Institute, Troy, New York, 12180-3590, USA.
Orig Life Evol Biosph. 2002 Aug;32(4):311-32. doi: 10.1023/a:1020543312109.
Elongation of the primer 32pdA(pdA)8pA proceeds by the reaction of the 5'-phosphorimidazolides of adenosine and uridine in the presence of montmorillonite clay. Daily addition of the activated nucleotides for up to 14 days results in the formation of 40-50 mers using the 5'-phosphorimidazolide of adenosine (ImpA) and 25-30 mers using the 5'-phosphorimidazolide of uridine (ImpU). The limitation on the lengths of the chains formed is not due to the inhibitors formed since the same chain lengths were formed using 2-3 times the amount of montmorillonite catalyst. The shorter oligomers formed by the addition of U monomers is not due to its greater rate of decomposition since it was found that both the A and the U adducts decompose at about the same rates. Alkaline phosphatase hydrolysis studies revealed that some of the oligomers are capped at the 5'-end to form, with ImpA, Ap32pdA(pdA)8pA(pA)n. The extent of capping depends on the reaction time and the purine or pyrimidine base in the activated mononucleotide. Hydrolysis with ribonuclease T2 followed by alkaline phosphatase determined the sites of the 3', 5'- and 2', 5'-phosphodiester bonding to the primer. The potential significance of the mineral catalyzed formation of 50 mer oligonucleotides to the origin of life based on RNA (the RNA world scenario) is discussed.
引物32pdA(pdA)8pA的延伸是通过腺苷和尿苷的5'-磷酰咪唑化物在蒙脱石粘土存在下的反应进行的。每天添加活化核苷酸，持续14天，使用腺苷的5'-磷酰咪唑化物（ImpA）可形成40 - 50聚体，使用尿苷的5'-磷酰咪唑化物（ImpU）可形成25 - 30聚体。形成的链长度受限并非由于形成了抑制剂，因为使用2 - 3倍量的蒙脱石催化剂时形成了相同的链长度。添加U单体形成较短的寡聚物并非由于其分解速率更高，因为发现A和U加合物的分解速率大致相同。碱性磷酸酶水解研究表明，一些寡聚物在5'-末端被封端，与ImpA一起形成Ap32pdA(pdA)8pA(pA)n。封端程度取决于反应时间以及活化单核苷酸中的嘌呤或嘧啶碱基。用核糖核酸酶T2水解后再用碱性磷酸酶处理，确定了与引物形成3', 5'-和2', 5'-磷酸二酯键的位点。讨论了矿物催化形成50聚体寡核苷酸对基于RNA的生命起源（RNA世界假说）的潜在意义。
