Synthesis, biological activity and isomerism of guanylate cyclase C-activating peptides guanylin and uroguanylin

J Pept Res. 1997 Sep;50(3):222-30. doi: 10.1111/j.1399-3011.1997.tb01188.x.


Recently, the peptides guanylin and uroguanylin were identified as endogenous ligands of the membrane-bound guanylate cyclase C (GC-C) that is mainly expressed in the intestinal epithelium. In the present study, bioactive guanylin and uroguanylin have been prepared by solid-phase methodology using Fmoc/HBTU chemistry. The two disulfide bonds with relative 1/3 and 2/4 connectivity have been introduced selectively by air oxidation of thiol groups and iodine treatment of Cys(Acm) residues. Using this strategy, several sequential derivatives were prepared. Temperature-dependent HPLC characterization of the bioactive products revealed that guanylin-related peptides exist as a mixture of two compounds. The isoforms are interconverted within approximately 90 min, which prevents their separate characterization. This effect was not detected for uroguanylin-like peptides. Synthetic peptides were tested for their potential to activate GC-C in cultured human colon carcinoma cells (T84), known to express high levels of GC-C. The results obtained show that both disulfide bonds are necessary for GC-C activation. The presence of the amino-terminally neighboring residues of Cys104 for guanylin and Cys100 for uroguanylin has been found to be essential for GC-C stimulation. Unexpectedly, a hybrid peptide obtained from substitution of the central tripeptide AYA of guanylin by the tripeptide VNV of uroguanylin was not bioactive.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Chlorides / metabolism
  • Chromatography, High Pressure Liquid
  • Colonic Neoplasms
  • Cyclic GMP / metabolism
  • Enzyme Activation
  • Female
  • Gastrointestinal Hormones*
  • Guanylate Cyclase / metabolism*
  • Humans
  • Ion Transport / drug effects
  • Molecular Sequence Data
  • Natriuretic Peptides
  • Peptides / chemical synthesis*
  • Peptides / chemistry
  • Peptides / isolation & purification
  • Peptides / pharmacology
  • Protein Conformation
  • Rats
  • Rats, Wistar
  • Tumor Cells, Cultured


  • Chlorides
  • Gastrointestinal Hormones
  • Natriuretic Peptides
  • Peptides
  • guanylin
  • uroguanylin
  • Guanylate Cyclase
  • Cyclic GMP