Table 1.

In vitro binding and agonist activity of opioid peptide analogues at the human MOR.

Opioid Peptide	Binding Affinity a	Agonist Activity b
	Ki (nM)	EC50 (nM)	% stim.
DAMGO	1.46 ± 0.37	18.1 ± 2.0	100
DALDA	6.36 ± 0.24	149 ± 28	92 ± 2
[Dmt1]DALDA	0.23 ± 0.02	0.51 ± 0.06	90 ± 4
KGOP01	0.11 ± 0.05	0.10 ± 0.02	99 ± 6

^a Determined in competitive radioligand binding assays using membrane from CHO expressing the human MOR (CHO-hMOR). ^b Determined in the [³⁵S]GTPγS binding assay using CHO-hMOR cell membranes. Percentage stimulation (% stim.) relative to DAMGO (reference MOR full agonist). Values are means ± SEM (n = 3-4 independent experiments).