May Jonathan P, Ting Richard, Lermer Leonard, Thomas Jason M, Roupioz Yoann, Perrin David M
Department of Chemistry, The University of British Columbia, Vancouver, B.C., V6T-1Z1 Canada.
J Am Chem Soc. 2004 Apr 7;126(13):4145-56. doi: 10.1021/ja037625s.
A DNAzyme, synthetically modified with both primary amines and imidazoles, is found to act as a M2+ -independent AP lyase-endonuclease. In the course of the cleavage reaction, this DNAzyme forms a covalent Schiff base intermediate with an abasic site on a complementary oligodeoxyribonucleotide. This intermediate, which is inferred from NaCNBH3 trapping as well as cyanide inhibition, does not evidently accumulate because the second step, dehydrophosphorylative elimination, is fast compared to Schiff base formation. The 5'-product that remains linked to the catalyst hydrolyzes slowly to regenerate free catalyst. The use of duly modified DNAzymes to perform Schiff base catalysis demonstrates the value of modified nucleotides for enhancing the catalytic repertoire of nucleic acids. This work suggests that DNAzymes will be capable of catalyzing aldol condensation reactions.
一种同时用伯胺和咪唑进行合成修饰的脱氧核酶，被发现可作为一种不依赖M2+的碱性磷酸酶-内切核酸酶。在切割反应过程中，这种脱氧核酶与互补寡脱氧核糖核苷酸上的无碱基位点形成共价席夫碱中间体。该中间体是通过NaCNBH3捕获以及氰化物抑制推断出来的，由于第二步脱氢磷酸化消除反应与席夫碱形成相比很快，所以它不会明显积累。与催化剂相连的5'产物缓慢水解以再生游离催化剂。使用经过适当修饰的脱氧核酶进行席夫碱催化证明了修饰核苷酸对于增强核酸催化功能的价值。这项工作表明脱氧核酶将能够催化羟醛缩合反应。
