Table 5.
Calculated ΔpKa | Calculated rate | |||||
Ionic strength (mM) | C147 | C204 | C147 | C204 | Enhancements avg.a | Observedb |
A. roGFP1-R8 | ||||||
50 | 0.033 | 0.074 | 0.928 | 0.844 | 0.886 | 0.857 |
100 | 0.020 | 0.054 | 0.954 | 0.883 | 0.919 | 0.886 |
150 | 0.015 | 0.043 | 0.967 | 0.905 | 0.936 | 0.873 |
250 | 0.009 | 0.032 | 0.979 | 0.929 | 0.954 | 0.924 |
350 | 0.007 | 0.025 | 0.984 | 0.943 | 0.964 | 0.928 |
CC:c | 0.88 | 0.91 | 0.90 | |||
B. roGFP1-R7 | ||||||
50 | –0.426 | –0.656 | 2.666 | 4.525 | 3.595 | 3.107 |
100 | –0.366 | –0.593 | 2.323 | 3.918 | 3.120 | 2.402 |
150 | –0.333 | –0.558 | 2.154 | 3.613 | 2.883 | 1.975 |
250 | –0.295 | –0.515 | 1.971 | 3.277 | 2.624 | 1.768 |
350 | –0.271 | –0.489 | 1.868 | 3.083 | 2.475 | 1.630 |
CC:c | 0.99 | 0.99 | 0.99 | |||
C. R7 with C-terminal residues removed | ||||||
50 | –0.421 | –0.596 | 2.636 | 3.947 | 3.291 | 3.107 |
100 | –0.346 | –0.511 | 2.217 | 3.246 | 2.731 | 2.402 |
150 | –0.304 | –0.463 | 2.014 | 2.901 | 2.458 | 1.975 |
250 | –0.255 | –0.403 | 1.798 | 2.531 | 2.164 | 1.768 |
350 | –0.224 | –0.365 | 1.677 | 2.319 | 1.998 | 1.630 |
CC:c | 0.99 | 0.99 | 0.99 |
a From ΔpKa, calculated using the program DelPhi (see Materials and Methods).
b From comparison of roGFP1 and full-length roGFP1-R7 or roGFP1-R8 experimental rate constants using DTT (see Materials and Methods).
c Correlation coefficient of calculated to experimental rate enhancements.