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. Author manuscript; available in PMC: 2012 Dec 13.
Published in final edited form as: J Med Chem. 2011 Oct 3;54(20):7375–7384. doi: 10.1021/jm2009937

Table 2.

Influence of linker length on affinity.

Compound Linker Estimated length between ligands (Å)a IC50 (nM) Relative potency to Ac-MSH(4)
Ac-MSH(4) - - 4600 ± 790 -
NB300 (Gly-Pro)3 60±20 620 ± 51 7
NB299 (Gly-Pro)2 52±20 410 ± 70 11
NB298 (Gly-Pro)1 45±20 220 ± 59 21
NB302 (β-Ala)2 48±10 120 ± 10 38
NB301 β-Ala 43±10 88 ± 12 52
NB297 No linker 35±10 71 ± 5.3 64
NB342 β-Ala 35±5 73 ± 3.5 63
NB341 No linker 24±5 14 ± 1.5 330

Competition experiments were carried out using time resolved fluorescence31. Multimers were competed against Eu-NDP-α-MSH. The IC50 values are the average of 4 experiments each done in quadruplicate.

a

Linker length was estimated from an energy-minimized structure using MacroModel.