Table 1.

20 MHz Relaxivity Values for GdL_1–3 ± Cu²⁺ and ± HSA and K_d Values for Binding of GdL_1–3–Cu²⁺ with HSA^a

in the absence of 0.6 mM HSA					in the presence of 0.6 mM HSA
	r1 (mM−1 s−1)				r1 (mM−1 s−1)
GdLx	no Cu2+	1 equiv of Cu2+*	% increase in r1	Kd (GdL–Cu2+)b (μM)	no Cu2+	1 equiv of Cu2+	% increase in r1	Kd (GdL–Cu2+–HSA)c (μM)
GdL1	4.7 ± 0.1	6.7 ± 0.1	43%	84 ± 10	6.1 ± 0.1 5.7 ± 0.1d	22.6 ± 0.2 15.4 ± 0.2d	270%	45 ± 3.1
GdL2	4.9 ± 0.2	5.5 ± 0.1	12%	895 ± 32	6.5 ± 0.2	14.5 ± 0.1	123%	59 ± 5
GdL3	4.8 ± 0.1	5.4 ± 0.2	12%	352 ± 9	6.3 ± 0.2	12.0 ± 0.2	90%	60 ± 10

^aAll experiments were performed in 0.1 M MOPS buffer (pH 7.4) at 37 °C.

^bK_{d(GdL–Cu²⁺)} was determined by fluorescence titrations.

^cK_{d(GdL–Cu²⁺–HSA)} was determined by proton relaxation enhancement titrations.

^dValues measured in the presence of 0.6 mM mouse albumin.