Template-directed synthesis of oligoguanylic acids - Metal ion catalysisThe effects of Zn(2+), Pb(2+) and other metal ions on the efficiency and stereo-selectivity of the template-directed oligomerization of guanosine 5'-phosphorimidazolide are investigated. Reactions were run in the presence of a polyC template in a 2,6-lutidine buffer, and products analyzed by high-performance liquid chromatography on an RPC-5 column. The presence of the Pb(2+) ion is found to lead to the formation of 2'-5' linked oligomers up to the 40-mer, while Zn(2+) favors the formation of predominantly 3'-5' linked oligomers up to the 35-mer. When amounts of uracil, cytidine or adenosine 5'-phosphorimidazole equal to those of the guanosine derivative are included in the reaction mixture, the incorrect base is incorporated into the oligomer about 10% of the time with a Pb(2+) catalyst, but less than 0.5% of the time with Zn(2+). The Sn(2+), Sb(3+) and Bi(3+) ions are also found to promote the formation of 2'-5' oligomers, although not as effectively as Pb(2+), while no metal ions other than Zn(2+) promote the formation of the 3'-5' oligomers. The results may be important for the understanding of the evolution of nucleic acid replication in the absence of enzymes.
Document ID
19820037397
Acquisition Source
Legacy CDMS
Document Type
Conference Proceedings
Authors
Bridson, P. K. (Salk Inst. for Biological Studies San Diego, CA, United States)
Fakhrai, H. (Salk Inst. for Biological Studies San Diego, CA, United States)
Lohrmann, R. (Salk Inst. for Biological Studies San Diego, CA, United States)
Orgel, L. E. (Salk Inst. for Biological Studies San Diego, CA, United States)
Van Roode, M. (Salk Institute for Biological Studies San Diego, CA, United States)