RNase activity of onconase or LL2-onconase conjugate
| RNase . | pH* . | Moles RNase per mole antibody† . | Km μM . | Kcat sec−1 . | Kcat/Km M−1 sec−1 . |
|---|---|---|---|---|---|
| Onc | 6.0 | N/A‡ | 7.7 | 0.02 | 2700 |
| LL2-Onc | 6.0 | 3.0 | 9.2 | 0.009 | 956 (0.4)1-153 |
| RNase . | pH* . | Moles RNase per mole antibody† . | Km μM . | Kcat sec−1 . | Kcat/Km M−1 sec−1 . |
|---|---|---|---|---|---|
| Onc | 6.0 | N/A‡ | 7.7 | 0.02 | 2700 |
| LL2-Onc | 6.0 | 3.0 | 9.2 | 0.009 | 956 (0.4)1-153 |
The RNase activity was measured at the pH most optimal for onconase. The data were derived from the initial rates of reactions containing 3 nM onconase and varying (0.1 to 1 mg/mL) concentrations of a yeast tRNA substrate.
The number of moles RNase conjugated per mole of antibody was determined spectrally at 412 nm by following the appearance of thionitrobenzoate ion (TNB). TNB is released from the 2-IT- and DTNB-treated antibody as disulfide bonds between the RNase and antibody are formed (see “Materials and methods”).
N/A, not applicable.
The number in parentheses indicates the percentage activity compared with onconase.