Table I.
Localization of proteolytic activity against exogenous LHCII apoprotein in intact etioplasts isolated from bean plants of various ages
| Sample | LHCII Degraded
|
||
|---|---|---|---|
| 7 d | 10 d | 11 d | |
| μg mg−1 protein min−1 | |||
| Intact plastids | 0.99 | 2.39 | 1.67 |
| Total membrane | 1.23 | 2.77 | 2.43 |
| PLBs | – | – | 2.37 |
| Prothylakoids | – | – | 2.55 |
| Stroma | 0.69 | 0.84 | 0.83 |
After isolation of intact etioplasts and their subfractions, the proteolytic activity of each sample was estimated. The assay mixture had 120 μg of protein from each sample and 20 μg of exogenous LHCII apoprotein (6 μg of LHCII in 10 μL of 1% TX-100) in 40 mm Tris-HCl, pH 8.6, at a final volume of 140 μL. Proteolysis was assessed by the LHCII apoprotein remaining after incubation at 37°C for 1 h, as monitored by immunodetection following western-blot analysis.