title: Oscillations of trypsinogen activation.
abstract: Trypsin activity oscillations are shown by the autocatalytic activation of trypsinogen at 0 degrees C in aqueous solution. The oscillations were observed for 3-4 days and show only slight decrease in enzyme activity. The zymogen has been kept at ice water temperature and pH 8.2 in the presence of Mn2+ ion. The mean periods of around 1.5 hr are about half of those found previously at -10 degrees C in frozen aqueous solution, while the amplitudes related to the mean activity are about one-fourth of that in the frozen experiments. The phenomenon of oscillation is interpreted in terms of coupling between the inhomogeneities of protein and ion concentrations of the unstirred solution and a Mn3+/Mn2+ system, causing synchronous, periodic reduction-oxidation of some cystine bridges in the protein chain. These nonequilibrium conditions, together with synchronous transitions among several conformational states, may produce the observed activity oscillations.
mesh_terms: D004789:Enzyme Activation; D005615:Freezing; D007700:Kinetics; D009991:Oscillometry; D014357:Trypsin / Q000378:metabolism; D014362:Trypsinogen / Q000378:metabolism*
chemical_list: D014362:Trypsinogen; D014357:Trypsin