Mode of disulfide bond formation of a heat-stable enterotoxin (STh) produced by a human strain of enterotoxigenic Escherichia coli

AbstractTo determine the modes of three disulfide linkages in the heat-stable enterotoxin (STh) produced by a human strain of enterotoxigenic Escherichia coli, we synthesized STh(6–18), which consists of 13 amino acid residues and has the same intramolecular disulfide linkages as native STh [(1985) FEBS Lett. 181, 138–142], by stepwise and selective formation of disulfide bonds using different types of removable protecting groups for the Cys residues. Synthesis of the peptide with different modes of disulfide bond formation provided three peptides consistent with standard STh(6–18) in their physicochemical and biological properties, thereby indicating that the disulfide bonds in STh(6–18) are

Amino acid sequence of heat-stable enterotoxin produced by Vibrio cholerae non-01

AbstractThe amino acid sequence of heat-stable enterotoxin, produced by Vibrio cholerae non-01 and isolated from its culture supernatant, was determined by both Edman degradation of native and reductively carboxy-methylated enterotoxin and also a combination of fast atom bombardment mass spectrometry and carboxy-peptidase Y digestion of native enterotoxin to be as follows: Ile-Asp-Cys-Cys-Glu-Ile-Cys-Cys-Asn-Pro-Ala-Cys-Phe-Gly-Cys-Leu-Asn. This sequence is very similar, but not identical, to those of heat-stable enterotoxins produced by enterotoxigenic Escherichia coli and Yersinia enterocolitica

Identification of the functional region on the superantigen Yersinia pseudotuberculosis-derived mitogen responsible for induction of lymphocyte proliferation by using synthetic peptides

AbstractYersinia pseudotuberculosis-derived mitogen (YPM) is the unique Gram-negative bacillary superantigen known. In order to identify the regions on the YPM molecule involved in its superantigenic activity, seven overlapping peptides of the entire YPM molecule were synthesized and tested to evaluate their effects on the YPM-induced proliferation of human peripheral blood lymphocytes. A peptide corresponding to the N-terminal amino acid sequence (1–23) was found to inhibit YPM-induced lymphocyte proliferation in a concentration-dependent manner. The N-terminal peptide was found to show no inhibition of the proliferation induced by the other superantigen (staphylococcal enterotoxin B) or the other T-cell mitogen pertussis toxin, indicating that the inhibition is specific to YPM-induced proliferation. Thus, we have identified the N-terminal region (1–23) of the YPM as one of the functional regions responsible for its superantigenic activity