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. Author manuscript; available in PMC: 2014 Jan 29.
Published in final edited form as: Biochemistry. 2013 Jan 15;52(4):752–764. doi: 10.1021/bi300723f

Table 7.

Binding and cAMP activities of Peptide 6 at human melanoma cells (A375)

Compound Structure IC50 Binding
Efficiency		 EC50t Act%
Peptide 6 c[(CH2)3-Gly-His-D-Phe-Arg-D-Trp-Cys(S-)]- Asp-Arg-Phe-Gly-NH2 92 ± 65 98 ± 41 22 ± 2.5 NA
 MT-II Ac-Nle-c[Asp-His-D-Phe-Arg-Trp-Lys]-NH2 6.7 ± 2.9 100 ± 10 110 ± 0.6 100
SHU9119 Ac-Nle-c[Asp-His-D-Nal(2′)-Arg-Trp-Lys]-NH2 100 ± 96 80 ± 34 3.3 ± 2.6 NA

IC50 = concentration of peptide at 50% specific binding (N=4). Binding Efficiency = maximal % of [125I]-NDP-α-MSH displacement observed at 10 μM. EC50 = Effective concentration of peptide that was able to generate 50% maximal intracellular cAMP accumulation (N=4). Act% = % of cAMP produced at 10 μM ligand concentration, in relation to MT-II. NA = 0% cAMP accumulation observed at 10 μM. The peptides were tested at a range of concentration from 10−10 to 10−5 M.