Table 3.
Effects of substituting positively charged side chains in the ligand pocket of the fluorescein-binding BBP variant FluA
Residue | Substitution | Kd, μM | Substitution | Kd, μM |
---|---|---|---|---|
FluA wild type | 0.427 ± 0.010 | |||
His-127 | Phe | 5.56 ± 0.05 | ||
Arg-58 | Lys | 25.1 ± 2.3 | ||
Arg-88 | Lys | 0.356 ± 0.008 | Gln | 2.23 ± 0.03 |
Arg-95 | Lys | 0.443 ± 0.012 | Gln | 0.918 ± 0.023 |
Arg-116 | Lys | 0.597 ± 0.019 | Gln | 1.54 ± 0.04 |
Kd values were measured for 4-glutarylamidofluorescein by fluorescence titration of the protein.