The non-enzymatic hydrolysis of oligoribonucleotides VI. The role of biogenic polyamines

Single-stranded oligoribonucleotides containing UA and CA phosphodiester bo nds can be hydrolyzed specifically under non-enzymatic conditions in the pr esence of spermidine, a biogenic amine found in a wide variety of organisms . In the present study, the rate of oligonucleotide and tRNA(i)(Met) hydrol ysis was measured in the presence of spermidine and other biogenic amines, It was found that spermine [H3N+(CH2)(3)+NH2(CH2)(4)+NH2(CH2)(3)+NH3] and p utrescine [H3N+(CH2)(4)+NH3] can replace spermidine [H3N+(CH2)(4)+NH2(CH2)( 3)+NH3] to induce the hydrolysis, For all three polyamines, a bell-shaped c leavage rate versus concentration relationship was observed. The maximum ra te of hydrolysis was achieved at 0.1, 1.0 and 10 mM spermine, spermidine an d putrescine, respectively, Moreover, we found that the hydrolysis requires at least two linked amino groups since two aminoalcohols, 2-aminoethanol a nd 3-aminopropanol, were not able to induce the cleavage of the phosphodies ter bond. The optimal cleavage rate of the oligoribonucleotides was observe d when amino groups were separated by tri- or tetramethylene linkers, The m ethylation of the amino groups reduced the ability of diamines to induce ol igoribonucleotide hydrolysis, Non-enzymatic cleavage of tRNA(i)(Met) from L upinus luteus and tRNA(i)(Met) from Escherichia coli demonstrate that both RNAs hydrolyze as expected from principles derived from oligoribonucleotide models.