Table 1.
Stretched exponential, powerlaw, and multiexponential fits for PGK and Ub*G under various conditions (final temperature and excitation wavelength shown and all times in μs).
| Conditions | exp[−(t/τ)β] | 1/[1 + (t/τ)]δ | Σ Aiexp[−t/τi] |
|---|---|---|---|
| Ub*G (8°C, 295 nm) | β ≤ 0.39, τ = 112 | δ = 0.59, τ = 32 | A1 = 1 − A2 − A3, τ1 = 23 A2 = 0.51, τ2 = 261, A3 = 0.11, τ3 > 2,000 |
| Ub*G (2°C, 295 nm) | β ≤ 1, τ = 5,000 | — | See stretched exponential |
| PGK (19°C, 280 nm) | β ≤ 0.65, τ = 475 | δ = 1, τ = 230 | A1 = 1 − A2, τ1 = 56, A2 = 0.65, τ2 = 890 |
| PGK (19°C, 295 nm) | β ≤ 0.83, τ = 3,770 | δ = 1.9, τ = 5,000 | A1 = 1 − A2, τ1 = 176, A2 = 0.91, τ2 = 4,250 |
| PGK (5°C, 280 nm) | β ≤ 1, τ = 700 | — | See stretched exponential |
| PGK (2°C, 295 nm) | β ≤ 1, τ = 2,400 | — | See stretched exponential |
| Calculation | β = 0.6 (T/Tg ≈ 1) to 0.8 (T/Tg ≈ 1.12) | ref. 11 | |
| Calculation | β = 0.3 (T/Tg ≈ 1) to 0.7 (T/Tg ≈ 2) | ref. 12 |
Also shown are calculations based on Monte Carlo dynamics of a lattice model of protein folding. With our choice of ft2 (Fig. 5), the β and δ values are upper limits, thus conservatively establishing the nonexponential kinetics. All multiexponential fits had positive amplitudes only.