Table IV.
Proteolytic degradation of endogenous (Endo) and exogenous (Exo) LHCII apoprotein by thylakoids obtained at different developmental stages
| Sample | Endo
LHCII
|
Exo LHCII Present | Endo + Exo LHCII Degraded | LHCII Degraded
|
||
|---|---|---|---|---|---|---|
| Present | Degraded | μg | % | |||
| μg | mg−1 protein min−1 | |||||
| 50 h of Dark | ||||||
| NS | – | – | 8 | 4.9 | 4.08 | 51.04 |
| S | – | – | 8 | 4.6 | 3.83 | 47.92 |
| 2 min of Light + 50 h of Dark | ||||||
| NS | – | – | 8 | 7.5 | 6.25 | 78.12 |
| S | – | – | 8 | 6.4 | 5.33 | 66.67 |
| 32 LDC | ||||||
| NS | – | – | 8 | 7.8 | 6.50 | 81.25 |
| S | – | – | 8 | 5.5 | 4.58 | 57.29 |
| 50 h of CL | ||||||
| NS | 15 | 5 | 8 | 9.6 | 12.80 | 55.65 |
| S | 15 | 15 | 8 | 20.5 | 27.33 | 118.84 |
Assay mixtures had 40 μg of thylakoid protein and 8 μg of exogenous LHCII apoprotein and were incubated at 37°C for 30 min. For immunoblots, 2 μg of total protein was loaded from the 48-h CL sample; 5 μg of total protein was loaded from all other samples. Nonsolubilized samples (NS) contained 0.05% TX-100; solubilized samples (S) had 0.5% TX-100. Estimation of the exact amount of immunodetected endogenous LHCII apoprotein was based on standard curves obtained from increasing known amounts of exogenous LHCII apoprotein immunoblotted on the same nitrocellulose membrane. Estimation of the rate in CL samples against endogenous + exogenous LHCII is based on total thylakoid protein after subtraction of the endogenous LHCII apoprotein.