Figure 2.

Chemical cleavage of oligonucleotides containing G (25G), Xan (25XAN) and Oxa (25OXA). 5′-³²P-labeled 25G, 25XAN and 25OXA were heated at 90°C for 30 min in an acidic aqueous solution (pH 3.5, adjusted by acetic acid) (lanes 3, 6 and 9). Alternatively they were incubated first in 30% (v/v) ammonia at 65°C for 4 h, and then in 10% (v/v) piperidine at 90°C for 30 min as described in Materials and Methods (lanes 4, 7 and 10). The samples were separated by 16% denaturing PAGE. Lane 1 shows a 5′-³²P-labeled marker (PRIM15). The bands of β-elimination, δ-elimination and 3′-OH products are indicated by arrows.