Table 1.
Rate constants and relative inhibitions for import of modified barnase precursor proteins across the outer and inner membranes
Precursor modification | Outer membrane
|
Inner membrane
|
||
---|---|---|---|---|
Import rate constant, min−1 | Import inhibition* | Import rate constant, min−1 | Import inhibition* | |
Unmodified | 2.4 ± 0.1 (n = 4) | N/A | 1.7 ± 0.1 (n = 5) | N/A |
Fluorescein | 2.1 ± 0.1 (n = 3) | 1.2 ± 0.1 | 1.5 ± 0.1 (n = 3) | 1.1 ± 0.1 |
Texas Red | 2.0 ± 0.1 (n = 3) | 1.2 ± 0.1 | 1.2 ± 0.1 (n = 4) | 1.5 ± 0.1 |
Undecagold | 2.2 ± 0.1 (n = 3) | 1.1 ± 0.1 | 0.8 ± 0.1†(n = 4) | 2.2 ± 0.2† |
Nanogold | No import | Infinite | No import | Infinite |
Import across the inner membrane was differentiated from import across the outer membrane by rupturing the outer membrane by osmotic shock before assaying for import. N/A, not applicable; n, number of repeat experiments.
Import rate constant of unmodified precursor divided by import rate constant of modified precursor.
The extent of import is greatly (≈4-fold) reduced, and therefore, a comparison of the import rate is problematic. Frequently, a decrease in the extent of import leads to an increase in the apparent rate constants, which here would lead to an underestimation of the inhibition.