Figure 5. Competition of unlabelled hLep or oLep with ¹²⁵I-hLep (180000–220000 c.p.m./tube) for binding to purified chLBD or chLBD mutants.

(A) Comparison of hLep and oLep capacity to compete with ¹²⁵I-hLep. The respective EC₅₀ values for hLep and oLep were 1.02 and 0.66 nM but the differences were within 95% confidence intervals and statistically not significant. The variability was low, so the S.E.M. values are in most cases not seen. (B) Comparison of oLep capacity to compete with ¹²⁵I-hLep for binding to chLBD or its mutants aimed at humanizing the chLBD or (C) with mutants aimed at decreasing the interaction of chLBD with leptin. Results are presented as means±S.E.M. for three experiments in (A) and as the mean for one experiment (in triplicates) in (B, C). Because of small differences in the maximal specific binding values obtained with WT chLBD and different mutants, which varied between 12 and 15%, the specific bindings obtained in each experiment were normalized to 100%. For other details, see text.