The designer leptin antagonist peptide Allo-aca compensates for short serum half-life with very tight binding to the receptor

Amino Acids. 2014 Apr;46(4):873-82. doi: 10.1007/s00726-013-1650-6. Epub 2013 Dec 24.


The leptin receptor antagonist peptide Allo-aca exhibits picomolar activities in various cellular systems and sub-mg/kg subcutaneous efficacies in animal models making it a prime drug candidate and target validation tool. Here we identified the biochemical basis for its remarkable in vivo activity. Allo-aca decomposed within 30 min in pooled human serum and was undetectable beyond the same time period from mouse plasma during pharmacokinetic measurements. The C max of 8.9 μg/mL at 5 min corresponds to approximately 22% injected peptide present in the circulation. The half-life was extended to over 2 h in bovine vitreous fluid and 10 h in human tears suggesting potential efficacy in ophthalmic diseases. The peptide retained picomolar anti-proliferation activity against a chronic myeloid leukemia cell line; addition of a C-terminal biotin label increased the IC50 value by approximately 200-fold. In surface plasmon resonance assays with the biotin-labeled peptide immobilized to a NeutrAvidin-coated chip, Allo-aca exhibited exceptionally tight binding to the binding domain of the human leptin receptor with ka = 5 × 10(5) M(-1) s(-1) and kdiss = 1.5 × 10(-4) s(-1) values. Peptides excel in terms of high activity and selectivity to their targets, and may activate or inactivate receptor functions considerably longer than molecular turnovers that take place in experimental animals.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cattle
  • Cell Line, Tumor
  • Drug Design
  • Female
  • Half-Life
  • Humans
  • Kinetics
  • Leptin / antagonists & inhibitors*
  • Leptin / chemistry
  • Leptin / metabolism
  • Mice
  • Peptides / blood
  • Peptides / chemistry*
  • Peptides / metabolism
  • Peptides / pharmacokinetics
  • Receptors, Leptin / chemistry*
  • Receptors, Leptin / metabolism


  • Leptin
  • Peptides
  • Receptors, Leptin