Table 2.

Time-resolved fluorescence anisotropy parameters of labeled apoMb as a function of increasing concentration of RNase A and HSA

Tracer + crowder	[crowder] (mg/mL)	β1 ±0.06	φ1 (ns)	β2 ±0.06	φ2 (ns)
apoMb-ANSa	0	—	9.0 (8.8–9.2)	—	—
80 μM	50	0.85	9.4 (8.8–10.1)	0.15	24 (23–25)
+RNase A	100	0.80	9.9 (9.0–10.8)	0.20	28 (25–30)
	150	0.61	10.8 (9.9–11.9)	0.39	36 (30–46)
	225	0.51	12.2 (10.7–14.0)	0.49	52 (41–69)
	250	0.40	12.4 (10.7–14.6)	0.60	54 (45–69)
ApoMb-Flb,c
2 μM
+ RNase A	200	0.30	0.28 ± 0.08	0.40	8.0 (5–14)
ApoMb-Flb	0	0.40	0.2 ± 0.05	0.60	9.9 (8.8–11.4)
2 μM	5	0.40	0.2 ± 0.05	0.60	10.2 (8.7–11.8)
+HSA	25	0.40	0.2 ± 0.05	0.60	10.6 (9.4–12.0)
	50	0.40	0.2 ± 0.05	0.60	10.7 (9.3–12.6)
	100	0.40	0.2 ± 0.05	0.60	11.4 (10.3–12.9)
	200	0.40	0.2 ± 0.05	0.60	13.6 (11.8–15.8)

The total concentration (labeled + unlabeled) of apoMb was 100 μM in all cases; 20 mM phosphate buffer, 150 mM NaCl, 0.1 mM EDTA, pH 7.4, 20°C.

^aλ_exc = 393 nm, λ_em = 465 nm. The resolution was 12.2 ps/channel. r(0) = 0.35 ± 0.01.

^bλ_exc = 460 nm, λ_em = 520 nm. The resolution was 13.1 ps/channel. r(0) = 0.25 ± 0.01.

^cβ_∞ = 0.3 ± 0.06.

Numbers in parenthesis represent the upper and lower limits of the recovered values (at the 67% confidence level) using rigorous error analysis, as described in Beechem et al. (1991).