title: Thiol reagents are substrates for the ADP-ribosyltransferase activity of pertussis toxin.
abstract: Thiols such as cysteine and dithiothreitol are substrates for the ADP-ribosyltransferase activity of pertussis toxin. When cysteine was incubated with NAD+ and toxin at pH 7.5, a product containing ADP-ribose and cysteine (presumably ADP-ribosylcysteine) was isolated by high-performance liquid chromatography, and characterized by its composition and release of AMP with phosphodiesterase. Cysteine has a Km of 105 mM at saturating NAD+ concentration. The ability of thiols to act as a substrate is one explanation for the very high concentrations (250 mM or greater) that have been observed to enhance the apparent NAD glycohydrolase activity of the toxin.
mesh_terms: D003545:Cysteine / Q000378:metabolism*; D004229:Dithiothreitol / Q000378:metabolism*; D007700:Kinetics; D009243:NAD / Q000378:metabolism; D037342:Pertussis Toxin; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism*; D013379:Substrate Specificity; D010566:Virulence Factors, Bordetella / Q000378:metabolism*
chemical_list: D010566:Virulence Factors, Bordetella; D009243:NAD; D011065:Poly(ADP-ribose) Polymerases; D037342:Pertussis Toxin; D003545:Cysteine; D004229:Dithiothreitol