The Open Spectroscopy Journal
2008, 2 : 34-39Published online 2008 December 15. DOI: 10.2174/1874383800802010034
Publisher ID: TOSPECJ-2-34
Structural Characterisation of the E. coli Heat Stable Enterotoxin STh
University of Bayreuth, Department
of Biopolymers & Research Center for Bio-Macromolecules, D-
95440 Bayreuth, Germany.
ABSTRACT
E. coli heat stable enterotoxin STa is an agonist of the membrane guanylate cyclase C whose endogenous ligands are the peptide hormones guanylin and uroguanylin. Whereas these peptides contain only two disulfide bonds, STa is stabilized by one additional disulfide bridge. We chemically synthesized the enterotoxin STh that originates from the E. coli strain found in humans, and we determined its structure and its dynamics by nuclear magnetic resonance spectroscopy and molecular dynamics calculations. Chemical synthesis clearly proved successful and resulted in the formation of the native disulfide bonds. The endogenous ligands guanylin and uroguanylin show the same general structural features and dynamics properties as the enterotoxin.