TABLE 2.
Fluorescence anisotropy decay parameters of YC3.60 on excitation at 400 nm or 492 nm and emission detection at 557 nm
| Sample | β1 | φ1 (ns) | β2 | φ2 (ns) |
|---|---|---|---|---|
| YC3.60 − Ca2+ (λex 400 nm) | 0.19 (0.17–0.22) | 1.29 (1.10–1.41) | 0.08 (0.06 – 0.10) | 31 (fixed) |
| YC3.60 + Ca2+ (λex 400 nm) | 0.13 (0.12–0.23) | 0.056 (0.047–0.069) | −0.060 (−0.063 to −0.057) | 50 (fixed) |
| YC3.60 − Ca2+ (λex 492 nm) | 0.368 (0.366–0.371) | 31.2 (29.8–32.7) | ||
| YC3.60 − Ca2+ (λex 492 nm) | 0.052 (0.043–0.063) | 5.1 (3.4–6.8) | 0.322 (0.310–0.332) | 50 (fixed) |
| YC3.60 + Ca2+ (λex 492 nm) | 0.360 (0.359–0.361) | 50.4 (47.8–53.3) |
Values in parentheses are the 67% confidence limits obtained from a rigorous error analysis. The recovered parameters in the first two entries (λex 400 nm) were obtained by associative analysis of fluorescence anisotropy decays (taken at two time ranges), in which the short fluorescence lifetimes (Table 1, case 3) were grouped with the short correlation times (φ1) and the long (fixed) fluorescence lifetimes with the long (fixed) correlation times (φ2). The recovered parameters in the fourth entry (λex 492 nm) were obtained after a bi-exponential decay analysis with the long correlation time (φ2) fixed to 50 ns. In this case the fitted curve had the same quality criteria as for the mono-exponential model (see Fig. 4).