Several generations of such conjugated compounds were synthesized with different linker properties (amino acid sequence or N-substituted succinimide moiety) and different types of leptin sequences (22–56; 57–92; 93–105; 116–130) in order to ameliorate the anti-obesity properties of the molecules (100, 101). This evidence concerns the gene LEP and obesity due to melanocortin 4 receptor deficiency.