. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. + ImpA Decamer 32 pdA(pdA)8p—j Q A. Figure 5. The reaction of ImpA with a decamer bound to rnontmoril- lonite. The other characteristic of the proposed RNA world would have been its ability to catalyze the reactions of other organics. It is not likely that the 10-15-mers formed by clay mineral catalysis have sufficient 3-dimensional tertiary structure to bind and catalyze the reactions of other RNAs. But oligo(A)s as long as 50 mers could be made in 14 days in so-called "feeding reactions," where an activated mono-
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. + ImpA Decamer 32 pdA(pdA)8p—j Q A. Figure 5. The reaction of ImpA with a decamer bound to rnontmoril- lonite. The other characteristic of the proposed RNA world would have been its ability to catalyze the reactions of other organics. It is not likely that the 10-15-mers formed by clay mineral catalysis have sufficient 3-dimensional tertiary structure to bind and catalyze the reactions of other RNAs. But oligo(A)s as long as 50 mers could be made in 14 days in so-called "feeding reactions," where an activated mono- mer (ImpA) was added daily to a decameric primer bound to the rnontmorillonite (Fig. 5) (12). Oligomers with a median number of 30 bases and as long as 50 bases were detected as reaction products. These oligomers may be long enough to exhibit catalytic activity (13, 14). This experiment sug- gests that long oligomers may have been formed on the primitive Earth by activated monomers reacting with short oligomers bound to the surface of a catalytic mineral. What remains to be done is to prepare, on rnontmorillonite, oli- gomers containing two or more complementary bases in a feeding reaction, and to test the mixture of polynucleotides that forms for catalytic activity. If catalysis is found in this experiment, we will have demonstrated that RNAs possess- ing the two essential elements for the RNA world—infor- mation storage and catalysis—form from simple monomers. Acknowledgments I thank my skillful collaborators, listed in the references, who supplied many of the ideas and most of the experimen- tal studies outlined in this review. The research was sup- ported by NSF grant CHE-9619149 and, in part, by NASA grant NAG Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Marine Biological Laboratory (
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