Fig. 5.

Stability of trimer T₂ in the absence or presence of poly(dA-dT) • poly(dA-dT). A sample of the more basic trimeric RNase A aggregate (T₂), dissolved (final concentration, 200 μg prot./mL) in 0.01 M imidazole/0.035 M NaCl buffer, pH 7, was maintained at 45°C for 2.5 min in the absence or presence of poly(dA-dT) • poly(dA-dT) (final concentration, 240 μg/mL). Aliquots, containing 12 μg of protein alone or mixed with 14.4 μg of the nucleic acid, were withdrawn and loaded on a TSK gel G2000 SW HPLC column. Elution was performed with 0.2 M sodium phosphate buffer, pH 6.7, at room temperature. The areas of the peaks eluted at the positions (previously determined with standard samples) of trimeric, dimeric, or monomeric RNase A were expressed as a percentage of the input. T₂, the trimer recovered after incubation at 45°C in the absence (empty bar) or presence (dark bar) of the nucleic acid. D and M, dimeric or monomeric RNase A, respectively, recovered as products of the dissociation of T₂ in the absence (empty bars) or presence (dark bars) of the nucleic acid. Retention time for poly(dA-dT) • poly(dA-dT) was 50 min versus 71 min for T₂, 76 min for D and 86 min for M.