. 2020 Sep 9;63(21):12929–12941. doi: 10.1021/acs.jmedchem.0c01376

Table 2. Binding Affinities of OP-NT Hybrids and Reference Peptides to the Human Opioid and NT Receptors.

	affinity K_i (nM)^a
peptide	MOR	DOR	KOR	NTS1	NTS2	selectivity NTS2/NTS1
KGOP01^b	0.14 ± 0.06	1.51 ± 0.26	16.6 ± 5.7	N/A^d	N/A^d	N/A^d
NT(8-13)^c	N/A^d	N/A^d	N/A^d	0.90 ± 0.03	0.55 ± 0.2	1.6
PK20	4.13 ± 1.4	46.4 ± 3.6	33.5 ± 6.2	188 ± 29	29.5 ± 11	6.4
1^c	N/A^d	N/A^d	N/A^d	3.6 ± 0.4	0.46 ± 0.03	7.8
2^c	N/A^d	N/A^d	N/A^d	3790 ± 1300	2.86 ± 1.3	1324
3	1.32 ± 0.45	56.4 ± 4.5	78.6 ± 20	0.43 ± 0.07	0.09 ± 0.07	4.8
4	4.89 ± 0.30	213 ± 44	201 ± 80	2.3 ± 0.4	0.29 ± 0.2	7.7
5	1.11 ± 0.39	159 ± 94	102 ± 8.0	0.78 ± 0.2	0.03 ± 0.03	27
6	7.15 ± 0.83	276 ± 42	138 ± 16	13 ± 1.3	0.16 ± 0.05	81
7	1.75 ± 0.43	101 ± 2.0	27.9 ± 4.1	4.0 ± 0.05	0.003 ± 0.001	1333
8	7.12 ± 2.0	48.6 ± 5.7	208 ± 76	15 ± 2	0.32 ± 0.5	50
9	1.67 ± 0.16	105 ± 35	22.4 ± 1.6	4710 ± 580	1.72 ± 4.0	2739
10	6.24 ± 0.48	209 ± 25	150 ± 53	6830 ± 4000	75.0 ± 80	91
11	1.73 ± 0.62	60.9 ± 8.6	19.9 ± 4.2	12.4 ± 0.9	0.33 ± 0.04	33
12	3.99 ± 0.97	200 ± 73	70.9 ± 15	59 ± 1.5	0.50 ± 0.45	118
13^c	N/A^d	N/A^d	N/A^d	2.3 ± 0.2	0.11 ± 0.07	20.1
14^c	N/A^d	N/A^d	N/A^d	13.4 ± 2.0	3.0 ± 2.0	4.5
15^c	N/A^d	N/A^d	N/A^d	6680 ± 3700	132 ± 47	50
16^c	N/A^d	N/A^d	N/A^d	93.0 ± 22	24.0 ± 18	4

Determined in competitive radioligand binding assays using membranes from CHO cells (opioid and NTS1 receptors) or 1321N1 astrocytoma cells (NTS2 receptors) stably expressing the human receptors. K_i values are reported as the means ± SEM of three independent experiments performed in duplicate (binding to the opioid receptors) or triplicate (binding to the NT receptors).

Data taken from ref (25).

Data taken from ref (11).

N/A, not applicable.