TABLE 1.

Characterization, GRPR Binding Affinity, and CatB Inhibition Activity of Conjugates

					CatB inhibition
Analog	Molecular formula	LogD (pH 7.4)	GRPR IC50 (nM)	CatB inhibition IC50 (nM)	Ki (nM)	ki/Ki (s−1⋅M−1)
E-AG	C93H148N28O28S	−3.13 ± 0.03	18 ± 4	26 ± 4	153 ± 17	89,000 ± 3,000
C-AG	C93H150N28O27S	−3.35 ± 0.09	16 ± 3	>1,000	—*	—*
E-AN	C105H163N29O30	−2.31 ± 0.18	20 ± 3	31 ± 6	107 ± 11	68,000 ± 8,000
C-AN	C105H165N29O29	−1.90 ± 0.14	24 ± 4	>1,000	—*	—*

^*No inhibition was observed in concentration range examined.

Data are mean ± SD (n = 3). LogD_7.4 values were obtained using ¹⁷⁷Lu-labeled conjugates. Inhibition constants were obtained at 37°C and pH 5.8 with human liver CatB.

K_i = the inhibition constants; K_i = the maximum inhibition rate.