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. 1999 Nov 9;96(23):13086–13090. doi: 10.1073/pnas.96.23.13086

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. 

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