TABLE 2.
Chymotrypsin-like activities of the purified M. jannaschii proteasomes and in vitro assembly of the α and β(Δpro) proteins
| Protein or proteasome | Preincubation temp (°C)a | Activityb |
|---|---|---|
| α | 0, 37, 65, 85 | UDc |
| β(Δpro) | 0, 37, 65, 85 | UD |
| α-β(Δpro)d | 0 | UD |
| α-β(Δpro) | 37 | 31.3 ± 1.55 |
| α-β(Δpro) | 65 | 48.2 ± 0.74 |
| α-β(Δpro) | 85 | 47.7 ± 3.01 |
| 700-kDa proteasomes | 0 | 106 ± 2.2 |
| ∼1.5-MDa proteasomes | 0 | 137 ± 8.6 |
a
Proteins (0.75 mg of protein per ml of Tris buffer) were preincubated at the indicated temperatures for 15 min.
b
Activity measured in micromoles per minute per milligram of protein. Hydrolysis of Suc-LLVY-Amc was measured at 37°C using 20 μM substrate and 0.06 mg of purified protein in 1 ml of Tris buffer with 6% (vol/vol) dimethyl sulfoxide.
c
UD, undetectable.
d
α-β(Δpro), equimolar ratios of the separately purified α and β(Δpro) proteins mixed prior to preincubation.