Kinetics curves (relative ODN concentrations as a function of time) of the 3′ hydrolysis of a 25 μmol/L solution of PO1 on incubation at 37°C in RPMI 1640 containing 2.5% HS. PO1-1, PO1-2, and PO1-3 represent, respectively, the PO1 sequence minus 1, 2, and 3 deoxyribonucleotides at the 3′ end. PO1 half-life (22 hours) is indicated by the position of the two arrows. The dashed curve (symmetrical to the PO1 curve) indicates the theoretical TMP relative concentration generated by hydrolysis of the PO1 3′ last linkage. The PO1-2 curve represents also the maximal d-AMP relative concentration generated by hydrolysis of the PO1-1 3′ last position.