δ Opioidmimetic Antagonists: Prototypes for Designing a New Generation of Ultraselective Opioid Peptides

Table 4 Hill coefficients and Statistical analysis for goodness-of-fit for one- and two-site δ receptor binding models

Peptide	Hill Coefficient (η)		Two-Site versus One-Site			Percentage Low Affinity Sites	K _i (nM)
Peptide	Mean	95% CI_log	DF	F	P	Percentage Low Affinity Sites	High	Low
1. Dmt-Tic-OH	−0.939 ± 0.040	−1.018 to −0.860	2;63	1.41	0.251	30.7 ± 91.5	0.022	—
2. Dmt-Tic-NH₂	−0.987 ± 0.044	−1.076 to −0.899	2;57	0.30	0.743	6.2 ± 40.1	1.06	—
5. Dmt-Tic-CH₂OH	−0.728 ± 0.032	−0.792 to −0.663	2;63	26.0	<0.0001	20.9 ± 5.3	0.13	5.2
11. Dmt-Tic-Ala-OH	−0.708 ± 0.036	−0.781 to −0.636	2;72	18.9	<0.0001	23.4 ± 6.5	0.12	4.8
12. Dmt-Tic-Ala-NH₂	−0.801 ± 0.030	−0.862 to −0.741	2;75	19.9	<0.0001	12.6 ± 3.7	0.18	10.7

The two-site versus one-site model presents degrees of freedom (DF), test of fitness (F) and probability (p). The values of percentage low affinity sites (mean ± SEM) further indicate the validity of the statistical approach and assignment to either high and/or low binding parameters. K_i, affinity constant; 95% CI_log, log of 95% confidence interval.

ISSN: 1528-3658