Table 1.
Estimates for RNA degradation using the quantitative model presented by Li & Breaker (14) and the model for AUP presented in this work.
| Simulated condition (0.14 M [K+]) | T (°C) | pH | [Mg2+] (mM) | RNA length (nucleotides) | AUPa | Cleavage rate per molecule (kdeg) (10−7 min−1) | Half-lifeb (days) |
|---|---|---|---|---|---|---|---|
| Refrigerated supply chain (‘cold chain’) | 5 | 7.4 | 0 | 4,000 | 0.4 | 5.1 | 941 |
| Refrigerated supply chain, increased length (SAM RNA) | 5 | 7.4 | 0 | 12,000 | 0.4 | 15.3 | 314 |
| Refrigerated supply chain, pKa shifted by cationic formulation | 5 | 9.4c | 0 | 4,000 | 0.4 | 470 | 10.2 |
| Temperature excursion | 37 | 7.4 | 0 | 4,000 | 0.4 | 890 | 5.4 |
| Manufacturing (in vitro transcription)d | 37 | 7.6 | 14 | 4,000 | 0.4 | 57,000 | 0.084 |
| Physiological | 37 | 7.4 | 1e | 4,000 | 0.4 | 2,000 | 2.4 |
a
Typical average unpaired probability (AUP) of 0.4 estimated from conventional design methods studied in this work.
b
Calculated as t1/2 = In 2/kdeg.
c
Apparent pH at 2´ hydroxyl, simulating pKa shift of 2 units induced by complexation with cationic lipid.
d
Ref. (20), with pH 7.9 of Tris-HCl buffer corrected from 25 °C to 37 °C.
e
Ref. (21).